Suppose I have a sump where water collects, and I want to pump this water out. The usual way is to immerse a pump in the sump with a float switch. When the float switch closes, the pump runs until it opens again. Simple.
But let's say I have a number of sumps, and I don't want to put a pump in each one. I can still fit the float switch to detect a full sump, to
trigger a remote pump.
One scenario is I have one remote pump per sump, and the pump is connected directly to the sump inlet.
Another scenario is I have a single pump and some kind of valve gear to select which sump to drain based on the float switch status.
Is there a kind of pump that will work in these cases? In a regular sump pump, the float switch is arranged so that the inlet to the pump is full of water and so the pump doesn't need priming. But in the remote setup it's quite possible the tube from the sump to the pump contains air, and we want
a pump that will suck out the air from the tube before the water will flow (the tube can be flexible if it helps).
Is this some kind of 'self priming' pump, or how would this be described?
The specific application I was thinking of was the condensate drains for air conditioners - typically they're mounted on the wall, and if it's not an external wall then you need to run the condensate drain up into the ceiling. 'Condensate pumps' exist, but they seem quite awkward to fit inside each
unit and it would be easier and quieter to put a remote pump somewhere far away. The problem here is that the whole point is to pump each sump dry, so there will be air in the system regularly.
What kind of valve gear would be suitable for the one-pump-many-inputs scenario? Is there something that could automatically cut off inputs that have too much of a pressure drop (ie are pulling air not water)?
Or is this not going to work?
Thanks
Theo
On 12/07/2025 14:42, Theo wrote:
Suppose I have a sump where water collects, and I want to pump this water out. The usual way is to immerse a pump in the sump with a float switch. When the float switch closes, the pump runs until it opens again. Simple.
But let's say I have a number of sumps, and I don't want to put a pump in each one. I can still fit the float switch to detect a full sump, to trigger a remote pump.
One scenario is I have one remote pump per sump, and the pump is connected directly to the sump inlet.
Another scenario is I have a single pump and some kind of valve gear to select which sump to drain based on the float switch status.
Is there a kind of pump that will work in these cases? In a regular sump pump, the float switch is arranged so that the inlet to the pump is full of water and so the pump doesn't need priming. But in the remote setup it's quite possible the tube from the sump to the pump contains air, and we want a pump that will suck out the air from the tube before the water will flow (the tube can be flexible if it helps).
Is this some kind of 'self priming' pump, or how would this be described?
Probably as a self priming pump? I think these are used for pumping
water in caravans or motor homes.
The specific application I was thinking of was the condensate drains for air
conditioners - typically they're mounted on the wall, and if it's not an external wall then you need to run the condensate drain up into the ceiling.
'Condensate pumps' exist, but they seem quite awkward to fit inside each unit and it would be easier and quieter to put a remote pump somewhere far away. The problem here is that the whole point is to pump each sump dry, so
there will be air in the system regularly.
There appears to be several devices available for this application e.g.
https://amzn.eu/d/9QhlRmg
&
https://amzn.eu/d/i7b59cR
What kind of valve gear would be suitable for the one-pump-many-inputs scenario? Is there something that could automatically cut off inputs that have too much of a pressure drop (ie are pulling air not water)?
Surely when pulling air the pressure drop is less? All the condensate
pumps I found use a water detection tank to switch the pump. These tanks don't seem much smaller than the smallest pumps..
Or is this not going to work?
I don't think this is going to work as you envisage. The problem would
be balancing it, so what happens if two units are running and both want
the pump...
Is this some kind of 'self priming' pump, or how would this be described?
David Wade <g4ugm@dave.invalid> wrote:
On 12/07/2025 14:42, Theo wrote:
Suppose I have a sump where water collects, and I want to pump this water >>> out. The usual way is to immerse a pump in the sump with a float switch. >>> When the float switch closes, the pump runs until it opens again. Simple. >>>Probably as a self priming pump? I think these are used for pumping
But let's say I have a number of sumps, and I don't want to put a pump in >>> each one. I can still fit the float switch to detect a full sump, to
trigger a remote pump.
One scenario is I have one remote pump per sump, and the pump is connected >>> directly to the sump inlet.
Another scenario is I have a single pump and some kind of valve gear to
select which sump to drain based on the float switch status.
Is there a kind of pump that will work in these cases? In a regular sump >>> pump, the float switch is arranged so that the inlet to the pump is full of >>> water and so the pump doesn't need priming. But in the remote setup it's >>> quite possible the tube from the sump to the pump contains air, and we want >>> a pump that will suck out the air from the tube before the water will flow >>> (the tube can be flexible if it helps).
Is this some kind of 'self priming' pump, or how would this be described? >>
water in caravans or motor homes.
It looks like 'self priming' is a search term, eg I'm finding things like coffee machine pumps. There are various kinds of self priming pumps though and not sure what's the best kind when having air in the system is commonplace.
The specific application I was thinking of was the condensate drains for air
conditioners - typically they're mounted on the wall, and if it's not an >>> external wall then you need to run the condensate drain up into the ceiling.
'Condensate pumps' exist, but they seem quite awkward to fit inside each >>> unit and it would be easier and quieter to put a remote pump somewhere far >>> away. The problem here is that the whole point is to pump each sump dry, so
there will be air in the system regularly.
There appears to be several devices available for this application e.g.
https://amzn.eu/d/9QhlRmg
&
https://amzn.eu/d/i7b59cR
I've seen those kind of things, the thing that isn't obvious is whether you can site the pump above the unit. Or do you need to find space to put the whole unit below the source of condensation, ie inside the air conditioner?
I think for the one-piece ones you do have to, but I'm not clear about the two piece ones? Is the idea that the tank is the remote float switch and
the pump can be above? The second one of your links has a video but has
both on the same level.
eg for this one piece unit according to the review pictures it's an ugly box mounted on the wall below the A/C unit: https://vi.aliexpress.com/item/1005008660395208.htm
This one comes in an ugly PVC drainpipe but suggests you can mount the pump uphill from the float, is that standard? https://www.amazon.co.uk/Siccom-FLOWATCH-Conditioning-Condensate-DE05LC9460/dp/B08WR7CLMW
What kind of valve gear would be suitable for the one-pump-many-inputs
scenario? Is there something that could automatically cut off inputs that >>> have too much of a pressure drop (ie are pulling air not water)?
Surely when pulling air the pressure drop is less? All the condensate
pumps I found use a water detection tank to switch the pump. These tanks
don't seem much smaller than the smallest pumps..
Yes, it seems that way. Perhaps easier to just duplicate pumps.
Or is this not going to work?
I don't think this is going to work as you envisage. The problem would
be balancing it, so what happens if two units are running and both want
the pump...
You would likely have to select one valve at a time, ie pump input 1 dry, then switch to input 2, etc. But if the pump is cheap enough, easier to duplicate pumps.
Theo
Theo wrote:
Is this some kind of 'self priming' pump, or how would this be described?
submersible pump?
David Wade <g4ugm@dave.invalid> wrote:
On 12/07/2025 14:42, Theo wrote:
Suppose I have a sump where water collects, and I want to pump this water >>> out. The usual way is to immerse a pump in the sump with a float switch. >>> When the float switch closes, the pump runs until it opens again. Simple. >>>Probably as a self priming pump? I think these are used for pumping
But let's say I have a number of sumps, and I don't want to put a pump in >>> each one. I can still fit the float switch to detect a full sump, to
trigger a remote pump.
One scenario is I have one remote pump per sump, and the pump is connected >>> directly to the sump inlet.
Another scenario is I have a single pump and some kind of valve gear to
select which sump to drain based on the float switch status.
Is there a kind of pump that will work in these cases? In a regular sump >>> pump, the float switch is arranged so that the inlet to the pump is full of >>> water and so the pump doesn't need priming. But in the remote setup it's >>> quite possible the tube from the sump to the pump contains air, and we want >>> a pump that will suck out the air from the tube before the water will flow >>> (the tube can be flexible if it helps).
Is this some kind of 'self priming' pump, or how would this be described? >>
water in caravans or motor homes.
It looks like 'self priming' is a search term, eg I'm finding things like coffee machine pumps. There are various kinds of self priming pumps though and not sure what's the best kind when having air in the system is commonplace.
The specific application I was thinking of was the condensate drains for air
conditioners - typically they're mounted on the wall, and if it's not an >>> external wall then you need to run the condensate drain up into the ceiling.
'Condensate pumps' exist, but they seem quite awkward to fit inside each >>> unit and it would be easier and quieter to put a remote pump somewhere far >>> away. The problem here is that the whole point is to pump each sump dry, so
there will be air in the system regularly.
There appears to be several devices available for this application e.g.
https://amzn.eu/d/9QhlRmg
&
https://amzn.eu/d/i7b59cR
I've seen those kind of things, the thing that isn't obvious is whether you can site the pump above the unit. Or do you need to find space to put the whole unit below the source of condensation, ie inside the air conditioner?
I think for the one-piece ones you do have to, but I'm not clear about the two piece ones? Is the idea that the tank is the remote float switch and
the pump can be above? The second one of your links has a video but has
both on the same level.
eg for this one piece unit according to the review pictures it's an ugly box mounted on the wall below the A/C unit: https://vi.aliexpress.com/item/1005008660395208.htm
This one comes in an ugly PVC drainpipe but suggests you can mount the pump uphill from the float, is that standard? https://www.amazon.co.uk/Siccom-FLOWATCH-Conditioning-Condensate-DE05LC9460/dp/B08WR7CLMW
What kind of valve gear would be suitable for the one-pump-many-inputs
scenario? Is there something that could automatically cut off inputs that >>> have too much of a pressure drop (ie are pulling air not water)?
Surely when pulling air the pressure drop is less? All the condensate
pumps I found use a water detection tank to switch the pump. These tanks
don't seem much smaller than the smallest pumps..
Yes, it seems that way. Perhaps easier to just duplicate pumps.
Or is this not going to work?
I don't think this is going to work as you envisage. The problem would
be balancing it, so what happens if two units are running and both want
the pump...
You would likely have to select one valve at a time, ie pump input 1 dry, then switch to input 2, etc. But if the pump is cheap enough, easier to duplicate pumps.
Theo
On 12/07/2025 17:18, Andy Burns wrote:
Theo wrote:
Is this some kind of 'self priming' pump, or how would this be
described?
submersible pump?
Different animal. Submersible pump usually needs to be under water to
work, and so does not need priming. Such pumps usually don't like to be
run dry.
A self-priming pump sits above water-level and sucks the water up, so it needs to be able to run dry. Often used in caravans where you have a
"water barrel" you fill at a tap, bring back to the caravan, drop a pipe
in and the pump sucks it up into the caravan..
https://www.argos.co.uk/product/8665382
Dave
On Sat, 12 Jul 2025 19:53:31 +0100, David Wade wrote:
On 12/07/2025 17:18, Andy Burns wrote:
Theo wrote:
Is this some kind of 'self priming' pump, or how would this be
described?
submersible pump?
Different animal. Submersible pump usually needs to be under water to
work, and so does not need priming. Such pumps usually don't like to be
run dry.
A self-priming pump sits above water-level and sucks the water up, so it
needs to be able to run dry. Often used in caravans where you have a
"water barrel" you fill at a tap, bring back to the caravan, drop a pipe
in and the pump sucks it up into the caravan..
https://www.argos.co.uk/product/8665382
Dave
The external pump I used with my caravan wasn't self priming.
The pump was on the end of a pipe which was submerged in the water carrier (Aquaroll) and sat on the botton.
So fully submerged when turned on.
Cheers
Dave R
| Sysop: | Keyop |
|---|---|
| Location: | Huddersfield, West Yorkshire, UK |
| Users: | 546 |
| Nodes: | 16 (2 / 14) |
| Uptime: | 00:38:15 |
| Calls: | 10,385 |
| Calls today: | 2 |
| Files: | 14,057 |
| Messages: | 6,416,570 |