Q. Do I Need a Room Thermostat ?

[Martin Clark 80]

I have a combi boiler and ALL the radiators had TRVS fitted. The boiler was recently overheating so the Worcester engineer removed the TRV in the hall so the heat can be circulated. This means that this radiator can't tell the boiler when the hall's warm enough so if the heating is timed to come on between say 5pm and 11pm the boiler stays on for that entire time.
Would a wireless wall thermostat in the hall help? Or would that shut the boiler down even though the other rooms aren't necessarily warm enough ?

 

[stem]

The problem with TRV's* is that they don't provide a 'boiler interlock' that switches off the boiler when all of the rooms are warm. So, the boiler will continue to operate unnecessarily and also waste energy. An electric room thermostat switches off the boiler completely when heat is not required.

AFAIK it is a requirement of building regulations and also most boiler instructions stipulate that it is necessary to have a 'boiler interlock' So yes you should have one, they are cheap and easy to fit so it's a 'no brainer' really. The room thermostat should be in a room where there isn't a TRV fitted to the radiator.

*Some TRV' systems such as Honeywell Evohome do provide the required boiler interlock.

 

[JohnD]

1) yes

2)

would that shut the boiler down even though the other rooms aren't necessarily warm enough ?

This is prevented by balancing the radiators so that the room with the TRV warms up slower than all the others. The hall is not necessarily the best place, though it was often done fifty years ago, and plumbers are traditionalists.

3) opinions differ, but a wireless stat has more to go wrong than a wired one.

 

[PullerGas]

1) yes

2)

This is prevented by balancing the radiators so that the room with the TRV warms up slower than all the others. The hall is not necessarily the best place, though it was often done fifty years ago, and plumbers are traditionalists.

3) opinions differ, but a wireless stat has more to go wrong than a wired one.

The Hall is by far the best location for a room thermostat, it's a central location & generally designed to have a lower ambient temperature, so will give a better average overall house temperature.

Recently, some ill advised house builders have sited room thermostats in Lounge/Livingrooms & it's a complete disaster. Most are having to alter the location to pacify home owners.
At the inconvenience of replacing batteries about once a year, RF room thermostats are a lot easier to fit & work very well.

 

[stem]

At the inconvenience of replacing batteries about once a year, RF room thermostats are a lot easier to fit & work very well.

Many wired thermostats also require batteries to operate, because the switched live supply from a programmer to the thermostat is not permanent. The batteries will last a bit longer than they do for the RF variants though.

 

[Martin Clark 80]

Thanks for your replies everyone. The boiler has the proper digital timer on the front so all is good on that score. I was worried that during the times wheñ the heatings set to be on it would constantly using gas and therefore cost a fortune.
However the pilot light seems to be off and on so it must be OK ? So no thermostat needed

 

[Doggit]

It's amazing how opinions differ. I feel that the room stat should be in the room you mainly live in, and the other rads should then be balanced so that they all heat the rooms up evenly. I have an ongoing disagreement with a plumber I know, in that he maintains that a rad is balanced by ensuring there is an 11degree drop between the flow and return pipes, whilst in my opinion, you balance the whole system so that everything is even. You move through a hallway, so if it's a little cooler, it's not an issue, but if the stats there, and the front door gets opened, then the boiler starts up again. My opinion of Trvs, is that they are a great idea, but I'm not convinced that they actually work properly, and I've yet to test out the new alcohol based ones that are supposed to react faster.

I've always found that systems with room stats are more efficient, than those without, and the bills are lower.

 

[JohnD]

Thanks for your replies everyone. The boiler has the proper digital timer on the front so all is good on that score. I was worried that during the times wheñ the heatings set to be on it would constantly using gas and therefore cost a fortune.
However the pilot light seems to be off and on so it must be OK ? So no thermostat needed

I wonder what is the benefit of having a heating system that keeps turning itself on, even when the house is fully warm.

You are just keeping the boiler and some pipes hot.

But why would you want to?

 

[muggles]

Wall thermostat always should be fitted in coldest room of the property.

By removing a TRV from one of your radiators you now have what is known as a 'bypass' to prevent the boiler overheating. The radiator never turns off. Ideal in the bathroom to keep towels dry.

Personally I wouldnt bother with a wall thermostat. Your TRV's do the same job!

Ideal to get a timer fitted to your boiler facia panel is possible.

Either have TRVs & no wall thermostat or no TRVs and a wall thermostat.

Care to explain how TRVs provide a boiler interlock as required by the regs? Or how not fitting TRVs complies?

 

[stem]

There are no fixed best places, as to where a room thermostat should go. A hallway may be good if it's cool, but not if it's totally internal, or south facing with a large glass area that is warmed by the sun. Every building is different, so the following principles should be considered when selecting a location.

1. The room thermostat should be in a room that is not overly effected by other sources of heat such as an open fire, cooking equipment, electrical appliances that generate heat, or direct sunlight. It should also, not be somewhere draughty, or too close to a window, especially if it's one that is opened in the winter.

2. It should be in a cool room, preferably the last to warm up.

3. The radiator in the room with the thermostat should not have a TRV fitted. Otherwise the room thermostat may never switch off, and it also maintains a water flow through the boiler.

4. It's height should be about 1.5 metres from the floor, and not close to, or above a radiator.

5. Preferably it should not be on an outside wall, (although if you have a new build, or one with well insulated walls, this is not quite so crucial)

6. It should be in an area where air can circulate easily, not behind curtains, or furniture.