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Where to put the thermostat

Discussion in 'Plumbing and Central Heating' started by ericmark, 5 Oct 2016.

  1. ericmark

    ericmark

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    The system has two thermostats, one for day and one for night, during the day the thermostat from experiment needs to be close to the radiator and high to compensate for being close to the radiator.

    However at night the room used has the radiator under the bay window, putting the thermostat near the radiator means it is sheltered by the wardrobe or on an outside wall, neither really a good location.

    Either too hot or too cold will mean my mother does not sleep the whole night so we will get interrupted sleep so keeping that room spot on is important. Most likely seems to be the wall between living room and bedroom, which is not very close to the receiving station so uncertain if it will work there anyway.

    It was a wired thermostat, but about 6 years ago my dad had the whole central heating changed and they ripped out the thermostat cables and went to a radio type. This was in the hall, and for some reason no TRV was fitted in the kitchen, wet room or hall.

    The control was a total failure it depended on wind direction, all attempts to regulate the TRV failed, and the living room would one day be sitting at 17°C the next at 27°C so I fitted a second radio controlled thermostat since in real terms there are only two rooms to worry about, the living room and bed room. So the time was set for the heating to go off with the living room thermostat at the same time as the time brought on the heat with the hall thermostat.

    It had some problems to start with, I placed the thermostat well away from the radiator and the hysteresis was silly, putting it a lot closer to the radiator did cure that problem.

    The bed room did have problems, and I realised the thermostat needed moving to the bed room, when the house was re-wired the thermostat was taken down and light switches replaced it. So now it's a case of drilling two holes and fitting in bed room. Simple I thought.

    However radiator under a bay window so thermostat can't go there, the 90° wall on one side is an outside wall and so not really the place for a thermostat fixed to a wall, and the other 90° wall has a wardrobe, then a TV so first section no free air movement and second section has heat from TV. Which leaves just the wall opposite to where the radiator is fitted.

    But being so far from the radiator is also a problem with hysteresis. So other than having a cord and hanging off the light fitting I really do not know where to put it. One thing very clear is a hall with massive drafts is not the place for a thermostat.

    Ideas please.
     
  2. NotSoNewboy

    NotSoNewboy

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  3. ericmark

    ericmark

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  4. Scarum

    Scarum

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    A temperature swing from 17 to 27 C in one day might mean insulating the house a good start, otherwise something needs to move:
    1. Move to another room
    2. Move wardrobe and tv
    3. Move house
     
  5. ericmark

    ericmark

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    The temperature swing is due to the bay window, in the afternoon the sun heats up the living room, in the morning the sun does heat bed room but not enough to worry about. For my wife and I it is not really a problem, but for my mother at 91 it is. We may end up with a AC unit, but if the hysteresis can be reduced that may not be required.

    I was really surprised on how the heat seems not to spread through the room so near the radiator very hot, but move to other side of the room and it is cool, having lived in a house with a Myson radiator for last 30 odd years I am not use to hot spots.
     
  6. unclebob1

    unclebob1

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    Just a thought, how are the two thermostats wired in and to what plumbing? could one be overriding the other to over heat?

    eg: downstairs is set to 20, upstairs is set to 21.
    downstairs temp is 18, upstairs is 16.
    both thermostats demand heat and so
    downstairs temp becomes 20, downstairs thermostat stops demanding heat, however upstairs is still only 18, so continues to demand heat.
    eventually thermostat upstairs reaches its desired temp of 21, however downstairs temp is now 25!
     
  7. ericmark

    ericmark

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    During the day not worried about bedroom temperature, the bedroom has upper limit controlled by TRV. At night not worried about living room temperature again upper limit controlled by TRV. Both thermostats wired in parallel the time clock is set so bedroom one is only active at night, and the day time thermostat has a low night temperature set.

    Theory the TRV should have controlled rooms, but in practice I was continually getting complaints of too hot or too cold. EvoHome would have been ideal, but when first set up only worried about two rooms. Both down stairs.

    There is like many houses a problem in that the down stairs heat goes upstairs and upstairs is always too hot. I have a curtain to reduce this around the stair case, but it has only limited success in keeping upstairs cool. All up stairs radiators have TRV and for us young ones (65) that is good enough.

    Thought about a TRV in the hall, but the hall never gets hot, it just goes upstairs, so using the lock shield valve is good enough. The wet room and kitchen only have towel rails so never get that hot.

    My mother (91) was educated in the days of coal fires, she moved to coke then gas, but the house was of poor design with no vents near the fires so massive drafts resulted, originally louvred windows in kitchen to allow the heat to escape from the solid fuel cooker. As a result my mother wants the doors closed all the time. If I could leave the doors open then the single thermostat may have worked, but I would open doors to either a cold draft or heat wave.

    Well thermostats now fixed, time will show if correct, I went into a very cold house and could not find the thermostat to turn up the temperature, so it was clear they needed fixing before they go missing again. Never liked the Horstmann HRFS1 as it seemed so slow to turn on the boiler or turn it off again. However fixed to the wall it seems to work better. I don't think there is any hand shaking they just tell the receiver to turn on or off for a fixed amount of time. Should anything stop the signal the boiler can get stuck on or off.

    I expected a packet system where the two units both received and transmitted so the thermostat would send and say turn off, did you get that, and the boiler end would say OK got that I am turning off. But it seems that is not the case.

    Originally was hard wired, but for some reason I fail to understand the new central heating installers cut off all the cables flush to wall and used wireless.
     
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