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  • Honeywell ST699 heating/hot water controller dead

    From Stamford@21:1/5 to All on Wed Feb 19 08:11:17 2025
    So woke up this morning got the heating and hot water blues...

    Honeywell ST699 controller is dead. There is power to the wiring system and boiler.

    It's an S plan dual valve system so have locked both motorised valves open and that's fired the boiler up.

    The controller is old but is there anything I can do to revive it.

    If not what is a recommended replacement.

    The system has no room thermostat only a hot water tank state, two motorised valves and boiler.

    Thanks

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  • From fred@21:1/5 to Stamford on Wed Feb 19 09:44:07 2025
    Stamford <user150@newsgrouper.org.invalid> wrote in news:1739952677-150@newsgrouper.org:


    So woke up this morning got the heating and hot water blues...

    Honeywell ST699 controller is dead. There is power to the wiring
    system and boiler.

    It's an S plan dual valve system so have locked both motorised valves
    open and that's fired the boiler up.

    The controller is old but is there anything I can do to revive it.

    If not what is a recommended replacement.

    The system has no room thermostat only a hot water tank state, two
    motorised valves and boiler.


    Although I haven't checked for your model, these are commonly powered by a dropper capacitor with a series resistor to limit inrush current. Either
    may have popped but the resistor will be more likely and easier to check. Remove and open unit to find the items, capacitor will be of non trivial
    size. Other faults may exist but those are the most likely.

    Alternatively Honeywell ST9400 seems to be the current popular replacement
    at 100quid or so and although the connections are different there are
    enough guides out there to set you right on the swap. Somehow I don't feel
    the replacement will last as long as the original, progressive display connection problems are not uncommon with those (zebra strip connected) displays.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Stamford@21:1/5 to All on Wed Feb 19 10:59:28 2025
    fred <not@for.mail> posted:

    Stamford <user150@newsgrouper.org.invalid> wrote in news:1739952677-150@newsgrouper.org:


    So woke up this morning got the heating and hot water blues...

    Honeywell ST699 controller is dead. There is power to the wiring
    system and boiler.

    It's an S plan dual valve system so have locked both motorised valves
    open and that's fired the boiler up.

    The controller is old but is there anything I can do to revive it.

    If not what is a recommended replacement.

    The system has no room thermostat only a hot water tank state, two motorised valves and boiler.


    Although I haven't checked for your model, these are commonly powered by a dropper capacitor with a series resistor to limit inrush current. Either
    may have popped but the resistor will be more likely and easier to check. Remove and open unit to find the items, capacitor will be of non trivial size. Other faults may exist but those are the most likely.

    Alternatively Honeywell ST9400 seems to be the current popular replacement
    at 100quid or so and although the connections are different there are
    enough guides out there to set you right on the swap. Somehow I don't feel the replacement will last as long as the original, progressive display connection problems are not uncommon with those (zebra strip connected) displays.

    Thanks - I've removed the ST699 from the base plate after a struggle and it looks like part of the PCB has burnt out.
    I will go get a 9400 as you suggest. I can see a good video on wiring it.

    I've tested the live feed to the programmer and it's OK so clearly it's time for a new one.

    --- SoupGate-Win32 v1.05
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