I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably less
in the summer.
I am thinking that solar panels and an air source heat pump should reduce overall running costs.
However it is possible that a poor installation would actually increase annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally high.
If her bills have gone up significantly after a "free" installation then
that opens a whole can of worms.
Cheers
Dave R
David wrote:
She is now struggling to pay the energy bills.
Reportedly £350 a month
Is that a disguised loan repayment for the 'free' system?
On 25/04/2025 19:30, David wrote:
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free
of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump
and gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free"
upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably
less in the summer.
I am thinking that solar panels and an air source heat pump should
reduce overall running costs.
However it is possible that a poor installation would actually increase
annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally
high.
If her bills have gone up significantly after a "free" installation
then that opens a whole can of worms.
Cheers
Dave R
switching from a gas fired heating & hot water system to an air source
heat pump actually worsens your EPC rating and as electricity is almost
4 x the cost of gas for the same amount of energy, your energy bills
will be higher.....
She is now struggling to pay the energy bills.
Reportedly £350 a month
David wrote:
In the absence of battery storage (which there isn't) I would assumePV is unlikely to ever generate enough to run an ASHP, assuming a not brilliantly insulated 30's semi, that could require a 10kW unit, so the
that the gas would be used any time the solar panels were not
generating enough to drive the ASHP.
PV will just offset some of the electricity costs over the year, and
sell some unused power back to the grid.
as electricity is almost 4 x the cost of gas for the same amount of
energy, your energy bills will be higher.....
In the absence of battery storage (which there isn't) I would assume thatPV is unlikely to ever generate enough to run an ASHP, assuming a not brilliantly insulated 30's semi, that could require a 10kW unit, so the
the gas would be used any time the solar panels were not generating enough
to drive the ASHP.
So it seems sensible to use the ASHP when electricity is being generated
to partially offset the cost, and use the gas when there is no electricity being generated.
Else why the hybrid system?
Unless the ASHP is run using off peak electricity and the gas is used to
top up.
David wrote:
So it seems sensible to use the ASHP when electricity is being
generated to partially offset the cost, and use the gas when there is
no electricity being generated.
Else why the hybrid system?
Unless the ASHP is run using off peak electricity and the gas is used
to top up.
All sorts is possible, you may have a lot of homework to do ...
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
I am thinking that solar panels and an air source heat pump should reduce overall running costs.
However it is possible that a poor installation would actually increase annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally high.
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably less
in the summer.
I am thinking that solar panels and an air source heat pump should reduce overall running costs.
However it is possible that a poor installation would actually increase annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally high.
If her bills have gone up significantly after a "free" installation then
that opens a whole can of worms.
SH wrote:
as electricity is almost 4 x the cost of gas for the same amount of
energy, your energy bills will be higher.....
You're not allowing anything for the CoP of the heatpump?
David <wibble@btinternet.com> wrote:
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of >> charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
1960s semi chalet bungalow with loft conversion here, ~110m2 - that's a bit bigger than the average Barratt idea of a 3 bed semi (~80m2) but in line
with some 1930s ones. Loft insulation is mediocre because of the conversion (and loft access is a PITA to fix that), but have cavity wall insulation. Uninsulated concrete floor.
13kW ASHP installed Dec 2021, so that's 1+12+12+12+4 = 41 months
Off the gas grid, so just electricity - replaced an oil boiler.
Consumption since 1 Dec 2021:
ASHP only: 11322.86kWh
Immersion heater (legionella cycle plus occasional free power from Octopus): 431.8kWh
Works out to be 11754.66kWh.
Let's say the price cap is 25p/kWh.
On 25/04/2025 19:52, Andy Burns wrote:
SH wrote:
as electricity is almost 4 x the cost of gas for the same amount of
energy, your energy bills will be higher.....
You're not allowing anything for the CoP of the heatpump?
Or that a gas boiler may be running at 80%. or less, efficiency.
On Fri, 25 Apr 2025 19:46:26 +0100, SH wrote:
On 25/04/2025 19:30, David wrote:
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free
of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump
and gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free"
upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably
less in the summer.
I am thinking that solar panels and an air source heat pump should
reduce overall running costs.
However it is possible that a poor installation would actually increase
annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally
high.
If her bills have gone up significantly after a "free" installation
then that opens a whole can of worms.
Cheers
Dave R
switching from a gas fired heating & hot water system to an air source
heat pump actually worsens your EPC rating and as electricity is almost
4 x the cost of gas for the same amount of energy, your energy bills
will be higher.....
I am intrigued by the hybrid system of a gas boiler and an air source heat pump.
There must (should?) be some fancy footwork to decide what to use.
In the absence of battery storage (which there isn't) I would assume that
the gas would be used any time the solar panels were not generating enough
to drive the ASHP.
However I sometimes take a simplistic view.
David wrote:
So it seems sensible to use the ASHP when electricity is being
generated to partially offset the cost, and use the gas when there is
no electricity being generated.
Else why the hybrid system?
Unless the ASHP is run using off peak electricity and the gas is used
to top up.
All sorts is possible, you may have a lot of homework to do ...
<https://www.worcester-bosch.co.uk/hybrid-systems#:~:text=A%20hybrid%> 20heating%20and%20hot%20water%20system%20is,boiler%20and%20an%20air%20to% 20water%20heat%20pump.>
That is my first homework assignment.
On 25/04/2025 19:52, Andy Burns wrote:
SH wrote:
as electricity is almost 4 x the cost of gas for the same amount of
energy, your energy bills will be higher.....
You're not allowing anything for the CoP of the heatpump?
Or that a gas boiler may be running at 80%. or less, efficiency.
On 25/04/2025 21:48, alan_m wrote:
On 25/04/2025 19:52, Andy Burns wrote:
SH wrote:
as electricity is almost 4 x the cost of gas for the same amount of
energy, your energy bills will be higher.....
You're not allowing anything for the CoP of the heatpump?
Or that a gas boiler may be running at 80%. or less, efficiency.
Only if it's old. Modern condensing gas boilers are around 94%.
On 25 Apr 2025 at 20:31:39 BST, David wrote:
David wrote:
All sorts is possible, you may have a lot of homework to do ...
<https://www.worcester-bosch.co.uk/hybrid-systems#:~:text=A%20hybrid%> 20heating%20and%20hot%20water%20system%20is,boiler%20and%20an%20air%20to% 20water%20heat%20pump.>
That is my first homework assignment.
Ah right, I live and learn! Seems diametrically opposed to the 'eco' aspect of
ASHP schemes, though. And 2 lots of heating plant to maintain. Look odd from a
quick look.
Consumption since 1 Dec 2021:
ASHP only: 11322.86kWh
Immersion heater (legionella cycle plus occasional free power from Octopus): >> 431.8kWh
Works out to be 11754.66kWh.
Let's say the price cap is 25p/kWh.
That's fairly close to our annual gas consumption for heating and hot
water (1930's semi, 3 to 5 occupants depending who's home from
university, wife in 24 hours a day due to disability). So with the cost differential between gas and electricity, it's pretty close in cost.
Shocker: boiler company wants to sell boilers. They've done this kind of distraction before with 'hydrogen ready' boilers - spoiler, hydrogen heating isn't going to be a thing. But it gets the punters to install a 'future proof' bog standard gas boiler.
switching from a gas fired heating & hot water system to an air source
heat pump actually worsens your EPC rating and as electricity is almost
4 x the cost of gas for the same amount of energy, your energy bills
will be higher.....
On 25/04/2025 21:48, alan_m wrote:Unfortunately, they arent. That is the tested figure, in ideal
Or that a gas boiler may be running at 80%. or less, efficiency.
Only if it's old. Modern condensing gas boilers are around 94%.
SH wrote:
as electricity is almost 4 x the cost of gas for the same amount of
energy, your energy bills will be higher.....
You're not allowing anything for the CoP of the heatpump?
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably less
in the summer.
I am thinking that solar panels and an air source heat pump should reduce overall running costs.
However it is possible that a poor installation would actually increase annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally high.
If her bills have gone up significantly after a "free" installation then
that opens a whole can of worms.
Cheers
Dave R
On 25/04/2025 20:57, Theo wrote:
David <wibble@btinternet.com> wrote:
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of >> charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and >> gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
1960s semi chalet bungalow with loft conversion here, ~110m2 - that's a bit bigger than the average Barratt idea of a 3 bed semi (~80m2) but in line with some 1930s ones. Loft insulation is mediocre because of the conversion
(and loft access is a PITA to fix that), but have cavity wall insulation. Uninsulated concrete floor.
13kW ASHP installed Dec 2021, so that's 1+12+12+12+4 = 41 months
Off the gas grid, so just electricity - replaced an oil boiler.
Consumption since 1 Dec 2021:
ASHP only: 11322.86kWh
Immersion heater (legionella cycle plus occasional free power from Octopus):
431.8kWh
Works out to be 11754.66kWh.
Let's say the price cap is 25p/kWh.
That's fairly close to our annual gas consumption for heating and hot
water (1930's semi, 3 to 5 occupants depending who's home from
university, wife in 24 hours a day due to disability). So with the cost differential between gas and electricity, it's pretty close in cost.
Just the extra capital cost of the ASHP and installation to skew the
figures.
On 25/04/2025 19:30, David wrote:
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free
of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump
and gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free"
upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably
less in the summer.
I am thinking that solar panels and an air source heat pump should
reduce overall running costs.
However it is possible that a poor installation would actually increase
annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally
high.
If her bills have gone up significantly after a "free" installation
then that opens a whole can of worms.
Is that £350 just for the coldest winter months or for all months?
I don't that there any grants for a hybrid ASHP+Gas for central heating.
Why would a properly designed ASHP need additional gas heating in a 3
bed semi?
Just the extra capital cost of the ASHP and installation to skew the
figures.
Indeed. A big chunk of that is covered by the Boiler Upgrade Scheme grant nowadays. Makes it roughly comparable with a gas boiler replacement, or cheaper in some cases.
As posted up thread, the hybrid system seems to be aimed at minimal installation cost.
No new plumbing and larger radiators.
No hot water storage.
So basically keep your existing system but add an additional heat source
to the mix (and tick a green credentials box).
The ASHP is (as far as I can see) equivalent to base load with gas used to top up any heating demand above the capabilities of the ASHP and to
provide hot water.
I am intrigued by the hybrid system of a gas boiler and an air source heat pump.
There must (should?) be some fancy footwork to decide what to use.
On 25/04/2025 19:54, David wrote:
I am intrigued by the hybrid system of a gas boiler and an air source
heat
pump.
There must (should?) be some fancy footwork to decide what to use.
The basic config allows the ASHP to signal the boiler to turn on when
the outside temperature reaches a low set point, this varies by Make, typically 5 degrees or so, just when the COP of the HP is going to take
a hit, so it is cheaper at that point to use the gas boiler.
A truly smart system can be fitted that will automatically allow
whatever energy source is the cheapest at that time to be used, for
example, the temperature may be 2 degrees outside, but a cheap rate of electric is available, so the system uses the HP at that time as it is
the cheapest way of heating, even if the COP is only 2.5 at that outside temperature. Solar can be integrated into the system too.
On 26 Apr 2025 at 10:51:07 BST, Theo wrote:
Just the extra capital cost of the ASHP and installation to skew the
figures.
Indeed. A big chunk of that is covered by the Boiler Upgrade Scheme grant >> nowadays. Makes it roughly comparable with a gas boiler replacement, or
cheaper in some cases.
Not in my experience. I got quotes around £15000 for the ASHP/HW cylinder, making my contribution after the grant £7500.
A decent gas boiler replacement < £3000.
On 25/04/2025 19:52, Andy Burns wrote:
SH wrote:
as electricity is almost 4 x the cost of gas for the same amount of
energy, your energy bills will be higher.....
You're not allowing anything for the CoP of the heatpump?
Or that a gas boiler may be running at 80%. or less, efficiency.
On 26/04/2025 09:31, Theo wrote:
Shocker: boiler company wants to sell boilers. They've done this kind of >> distraction before with 'hydrogen ready' boilers - spoiler, hydrogen
heating
isn't going to be a thing. But it gets the punters to install a 'future
proof' bog standard gas boiler.
It's likely to be 90% natural gas and a 10% hydrogen (maybe 80/20%) mix
at best and not the misleading 100% hydrogen green hype.
David wrote:
She is now struggling to pay the energy bills.
Reportedly £350 a month
Is that a disguised loan repayment for the 'free' system?
David <wibble@btinternet.com> wrote:
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of >> charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
1960s semi chalet bungalow with loft conversion here, ~110m2 - that's a bit bigger than the average Barratt idea of a 3 bed semi (~80m2) but in line
with some 1930s ones. Loft insulation is mediocre because of the conversion (and loft access is a PITA to fix that), but have cavity wall insulation. Uninsulated concrete floor.
13kW ASHP installed Dec 2021, so that's 1+12+12+12+4 = 41 months
Off the gas grid, so just electricity - replaced an oil boiler.
Consumption since 1 Dec 2021:
ASHP only: 11322.86kWh
Immersion heater (legionella cycle plus occasional free power from Octopus): 431.8kWh
Works out to be 11754.66kWh.
On 26/04/2025 15:12, RJH wrote:
On 26 Apr 2025 at 10:51:07 BST, Theo wrote:moving it to a new location and removing and disposal of redundant pipework.
Just the extra capital cost of the ASHP and installation to skew the
figures.
Indeed. A big chunk of that is covered by the Boiler Upgrade Scheme grant >>> nowadays. Makes it roughly comparable with a gas boiler replacement, or >>> cheaper in some cases.
Not in my experience. I got quotes around £15000 for the ASHP/HW cylinder, >> making my contribution after the grant £7500.
A decent gas boiler replacement <£3000.> My gas boiler replacement cost just
around £3000 and that included
I read recently that the average cost of installing an ASHP from Octopus
was in the region of £11k (incl the £7.5k grant).
On 25/04/2025 19:30, David wrote:
I know, I know, piece of string etc.With electricity several times more expensive than gas and solar panels
A distantly related family member has had a "green energy upgrade"
free of
charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably less
in the summer.
I am thinking that solar panels and an air source heat pump should reduce
overall running costs.
However it is possible that a poor installation would actually increase
annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally
high.
If her bills have gone up significantly after a "free" installation then
that opens a whole can of worms.
Cheers
Dave R
being pointless in winter, heat pumps are way more expensive than gas
even in a building that is insulated to the nines.
]Well a full passive house, there should be so much insulation
On Fri, 25 Apr 2025 21:41:35 +0100, alan_m wrote:
On 25/04/2025 19:30, David wrote:
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free
of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump
and gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free"
upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably
less in the summer.
I am thinking that solar panels and an air source heat pump should
reduce overall running costs.
However it is possible that a poor installation would actually increase
annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally
high.
If her bills have gone up significantly after a "free" installation
then that opens a whole can of worms.
Is that £350 just for the coldest winter months or for all months?
I don't that there any grants for a hybrid ASHP+Gas for central heating.
Why would a properly designed ASHP need additional gas heating in a 3
bed semi?
As posted up thread, the hybrid system seems to be aimed at minimal installation cost.
No new plumbing and larger radiators.
No hot water storage.
So basically keep your existing system but add an additional heat source
to the mix (and tick a green credentials box).
The ASHP is (as far as I can see) equivalent to base load with gas used to top up any heating demand above the capabilities of the ASHP and to
provide hot water.
I am not convinced of any major benefits beyond improving your carbon footprint.
Cheers
Dave R
On 26/04/2025 09:42, alan_m wrote:
On 26/04/2025 09:31, Theo wrote:By the time it gets to the end-user, it will be closer to 100% natural
Shocker: boiler company wants to sell boilers. They've done this
kind of
distraction before with 'hydrogen ready' boilers - spoiler, hydrogen
heating
isn't going to be a thing. But it gets the punters to install a 'future >>> proof' bog standard gas boiler.
It's likely to be 90% natural gas and a 10% hydrogen (maybe 80/20%)
mix at best and not the misleading 100% hydrogen green hype.
gas, unless they replace all the nations underground pipework. There
are millions of houses that still have bits of 3/4 screwed iron and
those pesky H2 molecules are just going to whizz out of the joints.
On 25/04/2025 20:57, Theo wrote:
Consumption since 1 Dec 2021:
ASHP only: 11322.86kWh
Immersion heater (legionella cycle plus occasional free power from Octopus):
431.8kWh
Works out to be 11754.66kWh.
Blimey, I use about 3000 KwH per year and for a about 20 years
since I ripped out the Baxi Bermuda back boiler and most of
the pipework (don't ask!), that includes minimal heating, and
only one room properly warm in winter.
I have a 37 degree pitch due-south-facing roof so solar PV
and a battery system would 'work' for me, but I don't have an
EV so the cost/benefit equation is tricky.
The big problem with heat pumps is the need to have quite a lot
of space for the internal pressure vessels and pumps etc, over
and over the HWC. I have the latter, but where did you put all
the other gubbins in your bungalow ?
On 26/04/2025 12:52, David wrote:
On Fri, 25 Apr 2025 21:41:35 +0100, alan_m wrote:Might be easier to have an air-to-air heat pump, and avoid
On 25/04/2025 19:30, David wrote:
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free >>>> of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump
and gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free"
upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially >>>> after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably
less in the summer.
I am thinking that solar panels and an air source heat pump should
reduce overall running costs.
However it is possible that a poor installation would actually increase >>>> annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so >>>> what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally
high.
If her bills have gone up significantly after a "free" installation
then that opens a whole can of worms.
Is that £350 just for the coldest winter months or for all months?
I don't that there any grants for a hybrid ASHP+Gas for central heating. >>> Why would a properly designed ASHP need additional gas heating in a 3 >>> bed semi?
As posted up thread, the hybrid system seems to be aimed at minimal
installation cost.
No new plumbing and larger radiators.
No hot water storage.
So basically keep your existing system but add an additional heat source
to the mix (and tick a green credentials box).
The ASHP is (as far as I can see) equivalent to base load with gas
used to
top up any heating demand above the capabilities of the ASHP and to
provide hot water.
I am not convinced of any major benefits beyond improving your carbon
footprint.
Cheers
Dave R
any plumbing changes. Add solar PV and a battery and you have
cheap/free air con in summer and in winter use the overnight
tariffs to charge the battery or run the heat pump.
Andrew <Andrew97d@btinternet.com> wrote:
On 25/04/2025 20:57, Theo wrote:
Consumption since 1 Dec 2021:Blimey, I use about 3000 KwH per year and for a about 20 years
ASHP only: 11322.86kWh
Immersion heater (legionella cycle plus occasional free power from Octopus):
431.8kWh
Works out to be 11754.66kWh.
since I ripped out the Baxi Bermuda back boiler and most of
the pipework (don't ask!), that includes minimal heating, and
only one room properly warm in winter.
That's over 4 winters, so about 3000kWh per year heating and hot water.
Heats the whole house 24/7/365, ie it's climate control - usually set to about 19C. It comes on when needed to boost the temp to 19C, no timers nothing. It's always comfortable, never cold.
I have a 37 degree pitch due-south-facing roof so solar PV
and a battery system would 'work' for me, but I don't have an
EV so the cost/benefit equation is tricky.
Yes, it's marginal. I'm looking at doing a bargain basement DIY solar install for the garage - 'second' panels about £35, I need to find a ~£50 used inverter and it'll be worth it just to cover standby power.
The big problem with heat pumps is the need to have quite a lot
of space for the internal pressure vessels and pumps etc, over
and over the HWC. I have the latter, but where did you put all
the other gubbins in your bungalow ?
There was a cylinder in the airing cupboard. This was replaced by combined 200l cylinder and 50l buffer, pumps and valves in front, expansion vessels
on the wall above. It lost about a foot of shelf space as the cylinder got taller, but the space above is still useful for storage, eg duvets.
Theo
On 26/04/2025 18:58, Theo wrote:
There was a cylinder in the airing cupboard. This was replaced by combined 200l cylinder and 50l buffer, pumps and valves in front, expansion vessels on the wall above. It lost about a foot of shelf space as the cylinder got taller, but the space above is still useful for storage, eg duvets.
So you lost your airing cupboard, whereas I have an airing cupboard
but nowhere else to take its place.
On 26/04/2025 09:42, alan_m wrote:
On 26/04/2025 09:31, Theo wrote:
Shocker: boiler company wants to sell boilers. They've done this
kind of distraction before with 'hydrogen ready' boilers -
spoiler, hydrogen heating
isn't going to be a thing. But it gets the punters to install a
'future proof' bog standard gas boiler.
It's likely to be 90% natural gas and a 10% hydrogen (maybe 80/20%)
mix at best and not the misleading 100% hydrogen green hype.
By the time it gets to the end-user, it will be closer to 100% natural
gas, unless they replace all the nations underground pipework. There
are millions of houses that still have bits of 3/4 screwed iron and
those pesky H2 molecules are just going to whizz out of the joints.
Might be easier to have an air-to-air heat pump, and avoid
any plumbing changes. Add solar PV and a battery and you have
cheap/free air con in summer and in winter use the overnight
tariffs to charge the battery or run the heat pump.
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably less
in the summer.
I am thinking that solar panels and an air source heat pump should reduce overall running costs.
However it is possible that a poor installation would actually increase annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally high.
If her bills have gone up significantly after a "free" installation then
that opens a whole can of worms.
Cheers
Dave R
On 26/04/2025 18:46, Andrew wrote:
Might be easier to have an air-to-air heat pump, and avoid
any plumbing changes. Add solar PV and a battery and you have
cheap/free air con in summer and in winter use the overnight
tariffs to charge the battery or run the heat pump.
You cannot get a grant for air to air and for air con in summer.
On 25/04/2025 19:40, Andy Burns wrote:
David wrote:
She is now struggling to pay the energy bills.
Reportedly £350 a month
Is that a disguised loan repayment for the 'free' system?
And why a heat pump *and* a gas boiler. This sounds a bit
odd.
Are we sure it isn't some sort of heat recovery system to
reduce condensation ?
On 26/04/2025 17:47, Andrew wrote:
On 25/04/2025 19:40, Andy Burns wrote:
David wrote:
She is now struggling to pay the energy bills.
Reportedly £350 a month
Is that a disguised loan repayment for the 'free' system?
And why a heat pump *and* a gas boiler. This sounds a bit
odd.
Are we sure it isn't some sort of heat recovery system to
reduce condensation ?
A gas boiler can still be used to give rapid warm-up of a building, that
a heat-pump may take a long period to get up to temperature. It can also
help on the coldest days, if necessary. It can provide almost unlimited
hot water.
Andrew <Andrew97d@btinternet.com> wrote:
On 26/04/2025 18:58, Theo wrote:
There was a cylinder in the airing cupboard. This was replaced by combined >>> 200l cylinder and 50l buffer, pumps and valves in front, expansion vessels >>> on the wall above. It lost about a foot of shelf space as the cylinder got >>> taller, but the space above is still useful for storage, eg duvets.
So you lost your airing cupboard, whereas I have an airing cupboard
but nowhere else to take its place.
Didn't lose it as it's double-width. The cylinder already occupied one
half, so only lost about 10% more of the total. If the install didn't have
a buffer tank (it didn't need one, but the ASHP manufacturer was a bit lazy) then it would have been the same as what we had before, just with a thicker jacket on the cylinder.
Could you put a hot water tank in your loft? There are horizontal unvented cylinders, eg: https://www.plumbnation.co.uk/horizontal-unvented-cylinders-295-0000
If you put it on top of a load bearing wall you shouldn't need to rely on dodgy joists. Used to live somewhere that had a solar thermal system and a 300 litre upright cylinder in the loft, positioned over a solid wall.
Theo
On 27/04/2025 08:21, alan_m wrote:That's what I suspect. And it may be that there is simply a jumper
On 26/04/2025 18:46, Andrew wrote:you don't need it. cost is so much lower. grant is a total white wash. I
Might be easier to have an air-to-air heat pump, and avoid
any plumbing changes. Add solar PV and a battery and you have
cheap/free air con in summer and in winter use the overnight
tariffs to charge the battery or run the heat pump.
You cannot get a grant for air to air and for air con in summer.
am sure they put the price up because they know you get a grant...
Dave
On 27/04/2025 15:53, SteveW wrote:
On 26/04/2025 17:47, Andrew wrote:
On 25/04/2025 19:40, Andy Burns wrote:
David wrote:
She is now struggling to pay the energy bills.
Reportedly £350 a month
Is that a disguised loan repayment for the 'free' system?
And why a heat pump *and* a gas boiler. This sounds a bit
odd.
Are we sure it isn't some sort of heat recovery system to
reduce condensation ?
A gas boiler can still be used to give rapid warm-up of a building,
that a heat-pump may take a long period to get up to temperature. It
can also help on the coldest days, if necessary. It can provide almost
unlimited hot water.
Unlimited hot water for what ??
Don't forget that until the 70s, the gas piped into homes was derived
from coal and was about 50% hydrogen. Pipework was pretty much all iron.
On 27/04/2025 12:26, David Wade wrote:
On 27/04/2025 08:21, alan_m wrote:That's what I suspect. And it may be that there is simply a jumper
On 26/04/2025 18:46, Andrew wrote:you don't need it. cost is so much lower. grant is a total white wash.
Might be easier to have an air-to-air heat pump, and avoid any
plumbing changes. Add solar PV and a battery and you have cheap/free
air con in summer and in winter use the overnight tariffs to charge
the battery or run the heat pump.
You cannot get a grant for air to air and for air con in summer.
I am sure they put the price up because they know you get a grant...
Dave
inside somewhere that disables air-con.
David <wibble@btinternet.com> wrote:
As posted up thread, the hybrid system seems to be aimed at minimal
installation cost.
No new plumbing and larger radiators.
No hot water storage.
So basically keep your existing system but add an additional heat
source to the mix (and tick a green credentials box).
The ASHP is (as far as I can see) equivalent to base load with gas used
to top up any heating demand above the capabilities of the ASHP and to
provide hot water.
I suspect that isn't going to work very well. The ASHP wants to run at
low flow temps, ideally ~35C. A traditional boiler system is designed
to run at 60-70C flow temps. If your radiators are right-sized for the boiler, they'll be too small to extract much heat from the heat pump.
<snip>
Theo
Which brings us back to the start of the thread, more or less.
It appears that a Council is supplying a hybrid system free of charge to improve the carbon footprint of houses.
However this "worthy" activity doesn't seem to be reducing the energy
costs to the householder and may even be increasing them.
A link to Worcester Bosch upstream somewhere talks about adding ASHP
without modification to existing systems. i.e. No larger radiators, no hot water storage. A Hybrid system.
I am charitably assuming that the ASHP will bring the radiators up to
around 30-40C and then the gas boiler will top this off to the design temperature of the radiators if the house is cool/cold.
In theory this should reduce gas usage by substituting efficient use of electricity in the CH.
As I have said, this looks like a fudge to me, to get an ASHP installed without the expensive infrastructure modification required for a proper
full ASHP install. Otherwise known as greenwashing.
Further information awaited.
As I have said, this looks like a fudge to me, to get an ASHP installed without the expensive infrastructure modification required for a proper
full ASHP install. Otherwise known as greenwashing.
On Sun, 27 Apr 2025 16:30:35 +0100, Andrew wrote:
On 27/04/2025 12:26, David Wade wrote:
On 27/04/2025 08:21, alan_m wrote:That's what I suspect. And it may be that there is simply a jumper
On 26/04/2025 18:46, Andrew wrote:you don't need it. cost is so much lower. grant is a total white wash.
Might be easier to have an air-to-air heat pump, and avoid any
plumbing changes. Add solar PV and a battery and you have cheap/free >>>>> air con in summer and in winter use the overnight tariffs to charge
the battery or run the heat pump.
You cannot get a grant for air to air and for air con in summer.
I am sure they put the price up because they know you get a grant...
Dave
inside somewhere that disables air-con.
I understand that you need planning permission for air to air.
David <wibble@btinternet.com> wrote:
On Sun, 27 Apr 2025 16:30:35 +0100, Andrew wrote:
On 27/04/2025 12:26, David Wade wrote:
On 27/04/2025 08:21, alan_m wrote:That's what I suspect. And it may be that there is simply a jumper
On 26/04/2025 18:46, Andrew wrote:you don't need it. cost is so much lower. grant is a total white wash. >>> I am sure they put the price up because they know you get a grant...
Might be easier to have an air-to-air heat pump, and avoid any
plumbing changes. Add solar PV and a battery and you have cheap/free >>>>> air con in summer and in winter use the overnight tariffs to charge >>>>> the battery or run the heat pump.
You cannot get a grant for air to air and for air con in summer.
Dave
inside somewhere that disables air-con.
I understand that you need planning permission for air to air.
No planning permission needs for a single air/air unit, but no grants if it can provide cooling (as I understand it).
On 28/04/2025 11:21, David wrote:
As I have said, this looks like a fudge to me, to get an ASHP installed
without the expensive infrastructure modification required for a proper
full ASHP install. Otherwise known as greenwashing.
Portugal, Spain and parts of France are without electricity right now.
Nothing to do with renewables. Oh no. Of course not.
In article <vunsal$39fto$1@dont-email.me>, The Natural Philosopher <tnp@invalid.invalid> scribeth thus
On 28/04/2025 11:21, David wrote:
As I have said, this looks like a fudge to me, to get an ASHP
installed without the expensive infrastructure modification
required for a proper full ASHP install. Otherwise known as
greenwashing.
Portugal, Spain and parts of France are without electricity right
now.
Nothing to do with renewables. Oh no. Of course not.
Not the Ruskis taking a practice before they sod up the UK grid;?..
In article <vunsal$39fto$1@dont-email.me>, The Natural Philosopher <tnp@invalid.invalid> scribeth thus
On 28/04/2025 11:21, David wrote:
As I have said, this looks like a fudge to me, to get an ASHP installed
without the expensive infrastructure modification required for a proper
full ASHP install. Otherwise known as greenwashing.
Portugal, Spain and parts of France are without electricity right now.
Nothing to do with renewables. Oh no. Of course not.
Not the Ruskis taking a practice before they sod up the UK grid;?..
On Mon, 28 Apr 2025 19:12:54 +0100
tony sayer <tony@bancom.co.uk> wrote:
In article <vunsal$39fto$1@dont-email.me>, The Natural Philosopher
<tnp@invalid.invalid> scribeth thus
On 28/04/2025 11:21, David wrote:
As I have said, this looks like a fudge to me, to get an ASHP
installed without the expensive infrastructure modification
required for a proper full ASHP install. Otherwise known as
greenwashing.
Portugal, Spain and parts of France are without electricity right
now.
Nothing to do with renewables. Oh no. Of course not.
Not the Ruskis taking a practice before they sod up the UK grid;?..
Why do you think Miliband needs help?
Tim+ <timdownieuk@yahoo.co.youkay> wrote:
David <wibble@btinternet.com> wrote:
On Sun, 27 Apr 2025 16:30:35 +0100, Andrew wrote:
On 27/04/2025 12:26, David Wade wrote:
On 27/04/2025 08:21, alan_m wrote:That's what I suspect. And it may be that there is simply a jumper
On 26/04/2025 18:46, Andrew wrote:you don't need it. cost is so much lower. grant is a total white
Might be easier to have an air-to-air heat pump, and avoid any
plumbing changes. Add solar PV and a battery and you have
cheap/free air con in summer and in winter use the overnight
tariffs to charge the battery or run the heat pump.
You cannot get a grant for air to air and for air con in summer.
wash.
I am sure they put the price up because they know you get a
grant...
Dave
inside somewhere that disables air-con.
I understand that you need planning permission for air to air.
No planning permission needs for a single air/air unit, but no grants
if it can provide cooling (as I understand it).
The issue last time I looked was that the grant requires a heat pump on
the MCS certified list, and no air to air units were.
I'm not sure whether air2air is covered anyway by the BUS grant anyway,
as: https://www.legislation.gov.uk/ukdsi/2022/9780348232349/regulation/9
"(2) A heat pump meets the suitability criteria in relation to the
eligible property, or a property to which regulation 14(1)(b) applies,
for which it is installed where—
(a)it provides heating—
(i)solely to that property, or to both that property and any related property, and
(ii)for the purpose of both space heating and hot water heating, using
liquid as a medium for delivering that heat,"
An air2air is pumping around a refrigerant, but at the point it's
delivering heat it's in the gas phase - once the heat is delivered it'll condense.
It's only when delivering cooling is the refrigerant in the liquid
phase.
Theo
my understanding is that you do needI remember RevK (of A&A fame) fell foul of it
to apply for permission to install an ASHP.
However the requirement was waived for heating only.
If I have enough energy I will search back for it.
I know, I know, piece of string etc.
A distantly related family member has had a "green energy upgrade" free of charge from the local council.
It consists of solar panels, a hybrid system of air source heat pump and
gas boiler.
She is now struggling to pay the energy bills.
Reportedly £350 a month, but further information being sought.
Also trying to find out what the bills were prior to the "free" upgrade.
We have a (modified) 1930s 3 bed semi with good insulation (especially
after the extension), good solar gain, gas heating and hob, electric
cooker and microwave.
Our annual predicted bill this month is just over £2,500.
Just over £300 for the coldest months of the year, but considerably less
in the summer.
I am thinking that solar panels and an air source heat pump should reduce overall running costs.
However it is possible that a poor installation would actually increase annual costs.
In which case the installation would not be appropriate.
I am now asking if anyone has an "average" 1930s 3 bed semi, and if so
what the energy bills look like over the year.
Just for a comparison, to see if the costs in her case are abnormally high.
If her bills have gone up significantly after a "free" installation then
that opens a whole can of worms.
Cheers
Dave R
On Mon, 28 Apr 2025 14:24:17 +0100, Theo wrote:
This was discussed some time ago, and my understanding is that you do need
to apply for permission to install an ASHP.
However the requirement was waived for heating only.
David <wibble@btinternet.com> wrote:
On Mon, 28 Apr 2025 14:24:17 +0100, Theo wrote:
This was discussed some time ago, and my understanding is that you do need >> to apply for permission to install an ASHP.
However the requirement was waived for heating only.
Yes. That's separate from being eligible for the grant. ie you can install air2air for heating only without needing PP (as long as there's only one outdoor unit), but you won't get a grant for it.
On 29 Apr 2025 at 22:15:28 BST, Theo wrote:
David <wibble@btinternet.com> wrote:
On Mon, 28 Apr 2025 14:24:17 +0100, Theo wrote:
This was discussed some time ago, and my understanding is that you do need >> to apply for permission to install an ASHP.
However the requirement was waived for heating only.
Yes. That's separate from being eligible for the grant. ie you can install
air2air for heating only without needing PP (as long as there's only one outdoor unit), but you won't get a grant for it.
https://www.revk.uk/2018/07/air-conditioning-at-home-planning.html
. . . Andy Burns gave suggests that a cooling heat pump does:
Shocker: boiler company wants to sell boilers. They've done this kind of distraction before with 'hydrogen ready' boilers - spoiler, hydrogen heating isn't going to be a thing. But it gets the punters to install a 'future proof' bog standard gas boiler.
I haven't heard of anyone with a Worcester-Bosch heatpump, they seem to be a bit of an also-ran. They buy them in from someone else I think.
On 26/04/2025 09:31, Theo wrote:
Shocker: boiler company wants to sell boilers. They've done this kind of distraction before with 'hydrogen ready' boilers - spoiler, hydrogen heating
isn't going to be a thing. But it gets the punters to install a 'future proof' bog standard gas boiler.
I haven't heard of anyone with a Worcester-Bosch heatpump, they seem to be a
bit of an also-ran. They buy them in from someone else I think.
Town gas had a fair bit of hydrogen in it. North sea conversion was just re-jetting - why wouldn't it be the same for a methane-hydrogen blend?
Or even put hydrogen?
Vir Campestris <vir.campestris@invalid.invalid> wrote:Ultimately the cost of simple non-heat pump boosted electrical heating
On 26/04/2025 09:31, Theo wrote:
Shocker: boiler company wants to sell boilers. They've done this kind of >>> distraction before with 'hydrogen ready' boilers - spoiler, hydrogen heating
isn't going to be a thing. But it gets the punters to install a 'future >>> proof' bog standard gas boiler.
I haven't heard of anyone with a Worcester-Bosch heatpump, they seem to be a
bit of an also-ran. They buy them in from someone else I think.
Town gas had a fair bit of hydrogen in it. North sea conversion was just
re-jetting - why wouldn't it be the same for a methane-hydrogen blend?
Or even put hydrogen?
I think that's what they mean by 'hydrogen ready' - either switch the jets over or the jets are designed to work with hydrogen. But they're really using it as a smokescreen because home heating by hydrogen isn't happening.
The CMA gave them a slap: https://www.gov.uk/government/news/investigation-into-boiler-company-over-green-claims
https://www.gov.uk/cma-cases/worcester-bosch-consumer-protection-case
Theo
Going back to where we started, as far as I can tell a hybrid system with
an air2air heat pump has no provision for cooling.
It would need an additional internal unit with a fan to blow cold air out.
RJH <patchmoney@gmx.com> wrote:
On 29 Apr 2025 at 22:15:28 BST, Theo wrote:
David <wibble@btinternet.com> wrote:https://www.revk.uk/2018/07/air-conditioning-at-home-planning.html
On Mon, 28 Apr 2025 14:24:17 +0100, Theo wrote:
This was discussed some time ago, and my understanding is that you
do need to apply for permission to install an ASHP.
However the requirement was waived for heating only.
Yes. That's separate from being eligible for the grant. ie you can
install air2air for heating only without needing PP (as long as
there's only one outdoor unit), but you won't get a grant for it.
. . . Andy Burns gave suggests that a cooling heat pump does:
Yes, that's why I said 'air2air for heating only'. But I don't know if
such a thing exists, or how far you need to go to disable cooling.
(on mine there is no way to fully disable cooling, but it was configured
to be controlled by a dry contact. They then deleted all mention of
cooling from the manual including this input - hey presto it doesn't do cooling)
Theo
David wrote:
Going back to where we started, as far as I can tell a hybrid system with an air2air heat pump has no provision for cooling.
You wouldn't really want cold radiators with condensation dripping off
them onto the carpets, would you?
Going back to where we started, as far as I can tell a hybrid system with
an air2air heat pump has no provision for cooling.
David <wibble@btinternet.com> wrote:
On Sun, 27 Apr 2025 16:30:35 +0100, Andrew wrote:
On 27/04/2025 12:26, David Wade wrote:
On 27/04/2025 08:21, alan_m wrote:That's what I suspect. And it may be that there is simply a jumper
On 26/04/2025 18:46, Andrew wrote:you don't need it. cost is so much lower. grant is a total white wash. >>>> I am sure they put the price up because they know you get a grant...
Might be easier to have an air-to-air heat pump, and avoid any
plumbing changes. Add solar PV and a battery and you have cheap/free >>>>>> air con in summer and in winter use the overnight tariffs to charge >>>>>> the battery or run the heat pump.
You cannot get a grant for air to air and for air con in summer.
Dave
inside somewhere that disables air-con.
I understand that you need planning permission for air to air.
No planning permission needs for a single air/air unit, but no grants if it can provide cooling (as I understand it).
Tim
Andy Burns <usenet@andyburns.uk> wrote:
David wrote:
Going back to where we started, as far as I can tell a hybrid system with >>> an air2air heat pump has no provision for cooling.
You wouldn't really want cold radiators with condensation dripping off
them onto the carpets, would you?
You can manage it if you limit the flow temp to above the dew point so there's no condensation. But radiators aren't great at distributing cold - fans are much better.
On 06/05/2025 14:37, Theo wrote:
Andy Burns <usenet@andyburns.uk> wrote:
David wrote:
Going back to where we started, as far as I can tell a hybrid system
with
an air2air heat pump has no provision for cooling.
You wouldn't really want cold radiators with condensation dripping off
them onto the carpets, would you?
You can manage it if you limit the flow temp to above the dew point so
there's no condensation. But radiators aren't great at distributing
cold -
fans are much better.
Fans are also much better at distributing heat. I have never understood
why there is so much animosity to air-distributed heating yet
air-distributed cooling (ie centralised air conditioning) is happily accepted.
<https://energysavingtrust.org.uk/advice/air-to-air-heat-pumps/>
On 06/05/2025 14:37, Theo wrote:
Andy Burns <usenet@andyburns.uk> wrote:
David wrote:
Going back to where we started, as far as I can tell a hybrid system with >>> an air2air heat pump has no provision for cooling.
You wouldn't really want cold radiators with condensation dripping off
them onto the carpets, would you?
You can manage it if you limit the flow temp to above the dew point so there's no condensation. But radiators aren't great at distributing cold - fans are much better.
Fans are also much better at distributing heat. I have never understood
why there is so much animosity to air-distributed heating yet
air-distributed cooling (ie centralised air conditioning) is happily accepted.
<https://energysavingtrust.org.uk/advice/air-to-air-heat-pumps/>
David <wibble@btinternet.com> wrote:
Going back to where we started, as far as I can tell a hybrid system
with an air2air heat pump has no provision for cooling.
Air2air can do cooling easily - you just reverse the refrigerant flow in
the system - the condenser turns into an evaporator and vice versa. A
hybrid system for that would just be two separate systems (one A/C and
one boiler with radiators) with shared controls.
It would need an additional internal unit with a fan to blow cold air
out.
ITYM air2water. The units can do cooling no problem, but radiators
aren't a good way to distribute that cold into the rooms. UFH or fan
coil units (FCUs, 'a unit with a fan to blow cold air out') are better.
Theo
Jeff Layman <Jeff@invalid.invalid> wrote:
On 06/05/2025 14:37, Theo wrote:
Andy Burns <usenet@andyburns.uk> wrote:
David wrote:
Going back to where we started, as far as I can tell a hybrid system with >>>>> an air2air heat pump has no provision for cooling.
You wouldn't really want cold radiators with condensation dripping off >>>> them onto the carpets, would you?
You can manage it if you limit the flow temp to above the dew point so
there's no condensation. But radiators aren't great at distributing cold - >>> fans are much better.
Fans are also much better at distributing heat. I have never understood
why there is so much animosity to air-distributed heating yet
air-distributed cooling (ie centralised air conditioning) is happily
accepted.
<https://energysavingtrust.org.uk/advice/air-to-air-heat-pumps/>
The thing is that the heat capacity of air is a lot lower than water. So
you have to blow a lot of air to get the same heating power, and that means noise.
That's mitigated somewhat if you have giant registers that blow a lot of air so the actual air speed and hence noise is low, but a typical wall split unit has a relatively small indoor coil and so a small fan and you need to spin
it fairly fast to push the airflow.
That might be bearable for a hot day in summer, but might be less attractive running all winter, especially at night.
Also this airflow is by definition draughty, which is nice and cooling on a hot day but not ideal when you are cold.
Not to say water systems are silent either, but it's possible to hunt down most of the ticking expansion noises and squash them using rubber pipe brackets.
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