Hall roomstat, TRVs and automatic door closers

[thrope]

I've moved into a new apartment (built around 2007).

It has a Potterton Powermax HE (condensing boiler with integrated unvented cylinder). There is a wall thermostat in the hallway. All radiators have TRVs (including the one in the hall way and all bathroom rails).

All the internal doors are fitted with automatic door closers (see my other post - still trying to decide whether to remove them).

I guess I am just trying to understand how the system is designed to work - or is it just the building regulations are not particularly well thought out or consistent? If all the doors are supposed to be closed what is the point of the hall thermostat? And how can the hall thermostat work when the hall radiator has a TRV? But the regulations say there has to be a roomstat and all doors have to have closers.

I can either wedge all the doors open, turn the TRVS up and use the hall thermostat, or leave the doors closed, turn the hall thermostat up and just use the TRVs (this is what I'd prefer actually).

I understand the TRVs don't shut off the pump - but is this really such an issue in practise or for this boiler? I am pretty sure it has a builtin bypass mechanism, but I doubt it has an automatic flow interlock (to cut off when the TRVs are closed).

 

[David937]

You are correct, the hallway rad shouldn't have a TRV if that's where your room stat is...however, you can set it to maximum so it never closes or just unscrew the head.

The purpose of the room thermostat is to stop the boiler firing once the house is up to temperature, set it to whatever temperature you like (usual setpoint is about 20-22ºc)* and the TRVs to suit individual rooms - for example, bedrooms at setting 2-3 which is about 19ºc and other areas a bit warmer. Provided everything is working OK, you shouldn't need to adjust the TRVs once set.

*you may need to experiment to make sure that it doesn't click off before other areas in the house are up to temperature. Once the thermostat is satisfied and has shut the boiler off, adjusting TRVs will have no effect.

 

[thrope]

Thanks - thats clear and I will try it next time I have the heating on.

My worry is that the hall will heat up much quicker than the rest of the flat and so I will have to set the thermostat high.

And then I wonder - can it really save energy to have the hall hot (I'm guess I will need the hall over 24-25 to have a comfortable 22 in the much bigger living room) when I would for preference not heat the hall at all and just do the living room with TRVs.

Wouldn't it use less gas keeping the internal water store at the operating temperature when the TRVs are off in the living room than it would heating the hall unnecessarily?

I know there is the issue of the pump running longer but how much electricity does that use, and does it really reduce the life substantially?

 

[St0rmer66]

Experiment with it. I very much doubt that you'd need it that much higher in the hall for the rest to be warm unless the living room radiator is undersized. 1 degree might be enough, most people find 21 is comfortable so 22 in the hall.

Pumps last for a very long time in a clean system, wearing it out through use is the least of your worries. Pumps which are sat too long not working are more likely to seize in my experience! Typical energy use for a standard efficiency pump is around 90-105watts on the highest speed. If you work it out over a year it really isn't very much cost wise.

P.S. I also hate those stupid automatic door closers! Luckily I don't have any in my ~1970 house but they'd be gone pretty sharpish if I ever do!

 

[thrope]

I will try it but I guess it will have to wait for the winter now.

Some other information is that the hall is a reasonable size and internal and isolated (with a main door to an internal communal area).

The main living room/kitchen area has full width full heigh glass fronting, which can be a bit draughty in high winds.

So I think the hall will stay toasty warm insulated by the automatically closed fire doors, while the living room will get cool from the draughts and large glass area.

Really I would much prefer to just use the TRVs and ignore the central thermostat - so I guess I am hoping someone will tell me thats not a terrible idea!

I know it doesn't turn off the boiler, but I don't see why keeping the idle circuit warm would use much more energy that keeping the hall warm and if the pump should last the lifetime of the other components then whats the problem?

Partly this is because I preivously lived in Germany where there is a central heating for the whole building, so I got used to having the heating available all the time and using TRVs in each room...

 

[Gasguru]

It might be better if you relocate the room thermostat to the living room (in a suitable position) and set those TRV heads to maximum ie. in effect they will never shut down.