Thermostat for Potterton Performa 24 Eco HE

Discussion in 'Plumbing and Central Heating' started by Shelvin, 18 Feb 2010.

  1. Shelvin

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    Bought a new house mid last year and have had Potterton Performa 24 Eco HE boiler with timer fitted. It has been installed probably 2 years ago and haven't had thermostat. I called local engineer and ask him about the thermostat and he said just use the temperature controller on the boiler, it will control the temperature in your house.

    I was on holiday in Jan (thank god missed the snow) and now back. I am leaving the CH on during the day till mid night using timer because wify and 4 months boy are at home all the time. We are controlling CH temperature by temperature controller available on the boiler. It does do the job but when the flame is off as CH is heated over the set temperature, the water is keeping circulating in CH system. So the flame turns on/off and adjust the temperature but water circulation never stops. I guess this is pretty standard.

    I am sure water circulation will use the electricity.
    Do you think I should install seperate Room thermostat to controll the temperature so that it will stop CH system completely?
    Is thermostate not needed for this kind of boiler as advised by local engineer?
    Is the electricity used by water circuculation very minimal?
    Does circulating water more efficient?
    If thermostat need then which is the good one?

    Thanks, Shelvin
     
  2. SamBrownExp

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    Hi Shelvin

    It might not be "needed" but I'd definitely recommend installing a digital programmable thermostat.

    Your family might be at home all day at the moment but presumably that won't always be the case, and it will be more energy efficient to be able to switch the heating off when no-one is at home.

    Honeywell Heating Controls UK are the market leaders for thermostats:

    http://www.honeywelluk.com

    You should be able to find what you're looking for there. Just make sure that the thermostat you buy is compatible with the 24 Eco HE, as some timers only work with certain models.

    If that fails, there are also "one fits all" thermostats on the market, much like the universal tv remotes you can buy. A quick Google search should find a selection of them.

    Sam
     
  3. Shelvin

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    Thanks Sam.

    It has Integral 24 Hour Electro-Mechanical timer which controlls on-off as CH is on timer and it gets turned off between 12 minight till 4 in the morning.

    The issue is, when is on and CH is heated enough, the flame stops but water pumping (circulation) in CH continues. I belive, having seperate room thermostat will stops everything - (not sure !!)

    That's why asking, is it worthing having seperate thermostat or leave water circulating?

    Thanks for suggestion for Honeywell. I know they are the market leader and having seperate electronic thermostat give more flexibility, like setting differrent settings by day but if there is any saving other than having additional functionality then I would go ahead with it.

    Thanks, Shelvin
     
  4. mikely

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    It is certainly worth having a thermostat, not only for the enhanced control and comfort it provides. As you suspect, this will prevent the CH pump and burner from running when there is no demand for heat (boiler interlock). For reasons of efficiency, Part L1 of the building regulations now requires all domestic CH systems to incorporate a boiler interlock to prevent continuous cycling of the boiler. With your current system, the heating pump is running continuously and the boiler is cycling to maintain the flow temperature, even when the house is warm enough. The pump will not use a lot of electricity, perhaps 50-100W but that adds up if running for 18 hours a day and its life will be shortened by running when not required.

    I agree that a Honeywell programmable thermostat would a very good choice.
     
  5. Shelvin

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    Hi Mikely,

    Thanks for you explanation. It doesn helps. I have also rang manufacturer technical line and they have advise to have seperate thermometer but didn't give proper explaination as you did.

    But they have suggest to have wired one than wireless. I know where they are comming from as me being IT person. Also to cost of typical traditional wired thermostat is arround £10 - £20 and programabale wireless one is arround £60-£80 so I thought going for wired as it's ceaper, providing I can run the wire from boiler to downstair.

    Any suggestion on this?
    Will any typical wired thermostat available in B&Q or Wickes do the job?
    Any particulat wire do I need to use?

    I guess it won't be difficult to connect the wires as I read in boiler manual.
     
  6. mikely

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    Yes, any wired thermostat will do the job, but I think it is worth paying the extra for a state-of-the-art device such as the Honeywell CM907 (programmable) or DT90 (non programmable). The thermostat is switching mains voltage so you need mains rated cable, such as twin and earth or three core and earth 1.0 or 1.5mm. Note that most mechanical thermostats require a neutral connection for the anticipator heater to function correctly, so a three core cable is needed.
     
  7. Shelvin

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    Thanks Mikely

    Sounds Installation of Mechanical thermostat may need more work probably. I have also checked running the cable would be difficult so I will check out the wireless you have suggested.

    Or may ask any local engineer to come to have look for wired one.

    Shelvin
     
  8. Shelvin

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    I was reading the manual in in Installation section found that.

    "If an integral timer is fitted to the boiler an external frost thermostat wired as shown will not operate correctly. Only external timers may be used in such installations, as in the diagram."

    http://www.potterton.co.uk/docs/Pot..._HE_Installation_and_Service_Instructions.pdf

    Page 31, figure 43

    I have option integral timer fitted so I have to remove it and use the external timer and thermostat. In that case I need not only thermostat but programmable thermostat.
     
  9. mikely

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    I think it says this because the frost thermostat would only work when the internal timer is on, so would not protect the system all the time. An external thermostat should work OK with the internal timer. It depends if you want the advantages of having programmable temperatures through the day which the programmable stat gives you.
     
  10. Shelvin

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    Hi Mikely,

    Sorry I misread it. You are right, it will work. I will go ahead and install the thermostat next weekend.

    Thank you so much for information you and Sam have provided. Much appreciated.

    Shelvin
     

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