Wall Thermostat Question

black-saturn

Please don't shoot the messenger! There was a plumber in my house at the time because my heating went wrong yesterday so I thought I'd ask him. Sorry if it was wrong but I have no idea personally what the answer is

Cardew

ollyk wrote:

Trouble with just having TRV's, is that you are regulating house temperature by monitoring the temperature of heating water returning to the boiler, not by directly monitoring the air temperature.
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I understand the point you are making, but of course TRV's do monitor air temperature.

A thermostatic radiator valve (TRV) has an air temperature sensor which is used to control the heat output from the radiator by adjusting water flow.

The reason why most TRVs have a dial with numbers and not temperatures is that all the user needs to do is set it to, say, 3 and if that is the comfortable temperature he requires in the room, the TRV has done its job.(Honeywell, who manufacturer the TRV's I have fitted, give approx temp equivalents to the numbers on the dial but stress that they are very approx and it depends where the TRV is situated.)

Frankly I don't care if the temperature in my hall(where most room thermostats are fitted) drops to 15C, I want to be able to set the temp in other rooms to the level I want; and I can't do that if the hall room thermostat is controlling my CH.

The downside of non-programmable TRVs is that I need to turn up/down the control every time I want to set a different room temperature.

I would concede that the best method is to have a completely automated system with combined programmable room thermostat, programmable TRV's and timer and so you can set timed temperature zones in the house.







They control

ollyk

Cardew wrote:

I understand the point you are making, but of course TRV's do monitor air temperature.

trouble with that, is they don't monitor air temperature very well at all - think about it, they are right next to the radiator! How can they factor in drafts and the heat that rises if they are by the primary heat source, and even worse by your feet...? How will having the TRV behind a sofa effect it's operation? there are just too many factors that can effect their 'reading' if you want to call it that - they also use a mechanical plunger method of controlling the temperature which has a hysterises that is wider than the monster of a fish I caught last week!
Yes they help with efficiency I guess obviously some are much better than others but seriously get a stat!
Also just remember you don't have to put the thermostat in the hall - sometimes it is not the place to put one!

Cardew

ollyk wrote:

trouble with that, is they don't monitor air temperature very well at all - think about it, they are right next to the radiator! How can they factor in drafts and the heat that rises if they are by the primary heat source, and even worse by your feet...? How will having the TRV behind a sofa effect it's operation? there are just too many factors that can effect their 'reading' if you want to call it that - they also use a mechanical plunger method of controlling the temperature which has a hysterises that is wider than the monster of a fish I caught last week!
Yes they help with efficiency I guess obviously some are much better than others but seriously get a stat!
Also just remember you don't have to put the thermostat in the hall - sometimes it is not the place to put one!

Again I agree with you(as do Honeywell) that the monitoring of temperature varies according to the position it is in the room.
However as I said above it doesn't matter about that. In the position I have them situated I set them to say, 3, and that maintains the temperature I want. (let us say 22C)

In another house the same TRV might need to be set at, say, 4 to maintain the room at 22C

All that matters is that they regulate the temperature at the level I want.

Incidentally I have a room stat - just don't use it. As I said I want individual control of temperature in every room.

I appreciate that you can have wall stat anywhere or several wired in parallel. However I have several reception rooms/bedrooms - no one place is suitable as we have a different patern of usage. Not using the dining room? turn the TRVs down. Not using the lounge? turn the TRVs down,

So what advantages do you suggest a wall stat gives me?
P.S.
Caught some fish this morning myself and will be eating a couple later.

sikejsudjek

Its part of building regs that all new systems should have room thermostats. The room stat should have a boiler lock out. This means that once the required temperature is reached the boiler is locked out, and won't fire up again until the room temperature drops. With just TRV's it might fire when the flow temp drops even if the valves have shut off and even if the temperature of the house is above what's required. Older systems might dry cycle with just trv's, wasting gas.

Having had a room stat fitted recently to a system previously with just trv's the temperature is much more even - and using a set back temperature during the day/night seems to save a lot of gas.

Cardew

sikejsudjek wrote:

Its part of building regs that all new systems should have room thermostats. The room stat should have a boiler lock out. This means that once the required temperature is reached the boiler is locked out, and won't fire up again until the room temperature drops. With just TRV's it might fire when the flow temp drops even if the valves have shut off and even if the temperature of the house is above what's required. Older systems might dry cycle with just trv's, wasting gas.

Having had a room stat fitted recently to a system previously with just trv's the temperature is much more even - and using a set back temperature during the day/night seems to save a lot of gas.

The latest Best practice Guidlines are here.
http://www.est.org.uk/uploads/documents/housingbuildings/CE51%20Final.pdf

You haven't said where your room stat is fitted? Also it would appear it is programmable?

Bear in mind that the OP is discussing the merits of a room stat in the hall which is open to the landing. Thus the stat will regulate the temp there and the other rooms will be???

My stat is in the hall, I set it way above the temp I require and with the radiators off or turned down with TRVs. So the CH is on whenever the timer brings it onand the boiler thus fires whenever the water temp drops.

I don't want the temp in my hall too warm. If I set the stat low, it will control the CH and turn it off when I want my, lounge warmer. Move stat to Lounge and I have the same problem when I am using another room.

Mrs_pbradley936

If I was the OP I would be more confused now than when I first asked!

Gadgee

Quite right pbradley936 - if nothing else the polarisation of views suggests to me that it is far from a black and white case!

Anyway - how come I am fidgetting about central heating bits when it seems that the rest of this thread are off catching fish?? If only the weather here would improve I then would be able to turn off the heating, get to the coast and boast of a catch as well!

Thanks to all who responded. At present I think I am going to be masterful and tell herself that we should stick to the status quo - that is until she decides differently.

Sooler

Tallymanjohn wrote:

there are even wireless ones available so no holes need drilling.

If you can use a wireless one you don't have to have it fixed anywhere, you can move it from room to room as you wish.

roswell

Thermostatic Radiator Valve (Does as it says on the tin it make sure the radiator is warm enough) you could say its a Thermostatic Room valve (if the room is the right temp it doesnt let water through)

A TRV Controls the temp of the ROOM it doesnt stop the boiler fireing up every 15 mins to see if the stats are open / closed.

Room/System stat says Temp is set at 22, temp is now below 22 Mr Boiler give me some heat, boiler warms up and heating is on, temp is now 22 boiler turns off. in 1 hours time or 2 or 3 or 4 when temp is below 22 it does the same again.

Use both or just one but if your only using one you may as well use the room/system stat because your TRV`s arent going to save your gas bill or electricity bill for the pump. They simply stop heating a room if its already hot enough. And i agree you should have at least one rad that isnt on a TRV.