Is there a formula as to where to place a thermostat?

[ericmark]

Hysteresis is always a problem with room thermostats old ones had heaters built in. Never thought about it much until I came to use a wireless portable thermostat to control my mothers living room.

I have two thermostats the original in hall timed to control at night and new one timed to control during the day and to start with placed on a writing bureau however it was noted there was a massive over shoot set to 23°C it would switch off and the room was still heating up plus the time for the heat to reach the thermostat which was centre of a wall 90° from the wall with radiator.

I have moved to tea trolley which would seem too close to radiator being only around a foot away however the hysteresis is massively reduced camera on bureau has thermometer built in it was showing 21 ~ 25°C now shows 21 ~ 22°C although the thermostat has to be set higher than required the temperature of the room is much more stable.

Until this I had never really thought about where the thermostat should be placed in regard to the radiator, well if anything I have always placed some distance from radiator to measure room temperature rather than spot temperature near the radiator, it seems I have been getting it wrong?

So is there any guidance given as to where it should be placed other than at 1200 mm from floor which the building regulations state is the max hight for items to be manually operated and min hight for items to be read which is to be frank silly anyway as able bodied people can bend down but wheel chair bound people can't rise up to read the device so 1000 mm is more like the hight required.

But I have seen nothing to say where to place in relation to radiator. Is there anything?

 

[Iggifer]

Honeywell's guide is about as good as ikea instructions....

 

[footprints]

Fitting a stat is just guesswork because houses vary so much in design, location and customer comfort expectations. Usually in an area that gives a fair approximation of the whole house hence often the hallway.
As far as I know it is just in free air away from draughts and direct heat, always a problem once a customer starts sticking a thermometer next to it (no offence intended ) the thing I said to customers is, are you comfy? If so forget it.
A bit like customers watching the oven burner moderate and turning it up or opening the door to get it back up again.

 

[ericmark]

I have in the past avoided out side walls as want room temperature not wall temperature. However the house used in is a three bedroom detached house where upstairs is not used all upstairs radiators set to frost protection and a curtain around the stairs to stop heat going upstairs.

So down stairs we have kitchen with towel rail only, wet room with electric under floor heating which is never used and a towel rail, a best room now converted into bedroom one radiator under window with TRV fitted, and a living room two radiators 90° to each other one under window both with TRV fitted, plus a hall way connecting all together.

Mother has lived pre-central heating and all efforts to stop her closing doors have failed. She will fiddle with the original thermostat in hall, so set stops to 16 ~ 24°C however living room often found at 28°C and mother de-hydrated which does not help the alzheimers so wanted to control the main living room and just leave other rooms to do their own thing during the day.

So the Honeywell Y6630D Wireless Room Thermostat and programmer has a [URL='http://www.screwfix.com/p/horstmann-hrfs1-programmable-room-thermostat/93829']Horstmann HRFS1 Programmable Room Thermostat wired in parallel the setting the originally to work at night only and the new having a low night time temperature set so at night hall temperature controlled low around 17°C and in day living room controlled 22°C morning to evening and 23°C evening to night. This have been a huge improvement, but as explained the hysteresis was higher than expected. [/URL]
[URL='http://www.screwfix.com/p/horstmann-hrfs1-programmable-room-thermostat/93829'][/URL]
I had considered a thermostatic TRV like this

but could not be sure it would fit existing valves and also not sure what happens when one room temperature is controlled without a link to the boiler? I know there is a very expensive system where the TRV heads talk to a central controller but since mother spends most of her time in one room controlling the boiler to maintain that room at correct temperature seemed a relatively cheap compromise. And yes it has worked, no longer do I visit and have to open all windows to cool the room down.

I have a WiFi camera with a thermometer built in so I am able to monitor from home the temperature. It was dropping to 19°C and going up to 25°C as the central heating lagged behind and over shot. It still can drop to 19°C on odd time but over shoot reduced to 23°C simply by moving where the free standing thermostat is placed.

The Horstmann HRFS1 Programmable Room Thermostat is very cheap for a wireless programmable thermostat and it does seem to be slow both switching off and on, it is set to lowest differential option and as said a huge improvement so much was considering one at my house.

But the more I look at mothers house the more I wonder if the thermostat should be very close to the radiator to stop the hysteresis but set high to compensate for being so close to the radiator this is of course exactly what the TRV does they don't put on any temperature just 1 ~ 6 and one adjusts to get room right. Great when living in the house, not so good when to adjust need to travel 15 miles.

Soon they are to knock a new door way between living room and bedroom hence thermostat not fixed to the wall but portable. My thoughts were to mount very close to new door so it would get an average of the two rooms. However after finding it worked so much better near the radiator I am going off that idea.

Hence the question.

 

[AndyPRK]

You should check its Calibration to if you are having problems.

It's amazing these modern fancy t stats that they can't even be bothered to calibrate it at the factory.

 

[PrenticeBoyofDerry]

locating a thermostat is generally common sense, there are number of variables to consider and some no nos!
It is not an exact science unless the stat has a brain and can compensate for certain factors.

 

[PBC_1966]

Unfortunately, common sense isn't always that common! The single thermostat in our home here is a case in point: Somebody mounted it in the hallway right below the air return inlet for the HVAC system, no doubt because it was quick and easy to wire with the unit on the roof directly above. On my list of jobs is to install multiple thermostats and motorized dampers to turn it into a zoned system.

 

[JohnW2]

As has been said, it probably comes down largely to common sense and, if one can (e.g. with a wireless stat), experimentation. I have always felt that on any wall (inevitably where they are found) is probably non-ideal, and that one or more sensor(s) 'dangling from the ceiling' in suitable places (maybe suitably camouflaged!) might well be the ideal, functionally if not aesthetically!

Kind Regards, John

 

[footprints]

The Ideal would be a body worn stat or one that identifies where occupant is and heats that zone to a pre-determined temperature, but all a bit Star Trek I fear.

 

[PrenticeBoyofDerry]

one that identifies where occupant is and heats that zone to a pre-determined temperature, but all a bit Star Trek I fear.

Nest claim that their thermostat can detect occupancy via CO2 levels!

 

[JohnW2]

deleted - wrong thread

 

[JohnW2]

duplicate deleted - things are going mad!

 

[PBC_1966]

Wouldn't the absolute ideal be to live in a place where the temperature is a constant 70 degrees or so? Then you needn't worrying about heating, cooling, or the thermostats for controlling them!

 

[footprints]

one that identifies where occupant is and heats that zone to a pre-determined temperature, but all a bit Star Trek I fear.

Nest claim that their thermostat can detect occupancy via CO2 levels!

Does that mean if you are a home brewer the heating stays on all the time!

 

[Taylortwocities]

Wouldn't the absolute ideal be to live in a place where the temperature is a constant 70 degrees or so?

70 degrees? We're in Europe, mate.