Two rads in one room, but only one TRV

[Roger465]

I have a house built in 1994, so not quite to the same standard as today, and I’m gradually replacing things to improve it – mostly to do with heating and insulation. Looking at the rads now… there are two in the living room, about the same size – but one has a TRV, the other doesn't. I don’t mean it’s broken off or something – it has the smaller thingy at each end (sorry, I’m not a plumber) that just lets you turn it full on or full off, I think. Anyway, when the heating’s on, that rad is on full all the time.



Yet the 2nd reception room, about the same size, has two rads, both with TRVs. What’s the logic?



PS there is no room stat in this house (yet) – the only way of changing the overall heat level is by the stat on the actual boiler…

 

[gasmanstu72]

unless you have a by-pass at least one radiator should have a normal valve (not TRV).
TRV's are automatic and shut down the water flow according to the air temperature, they could theoretically all shut down at once giving the pump nowhere to pump the water which isn't a good thing. so with this in mind you need at least one that's always open so if they all do shut down the water has somewhere to go. most have this in the hallway or bathroom as that's where you always need heat.
the other option is to have a by-pass which will act like your normal valve if all TRV's shut. if you have a by-pass you can have TRV's on every radiator.

 

[Roger465]

unless you have a by-pass at least one radiator should have a normal valve (not TRV).
TRV's are automatic and shut down the water flow according to the air temperature, they could theoretically all shut down at once giving the pump nowhere to pump the water which isn't a good thing. so with this in mind you need at least one that's always open so if they all do shut down the water has somewhere to go. most have this in the hallway or bathroom as that's where you always need heat.
the other option is to have a by-pass which will act like your normal valve if all TRV's shut. if you have a by-pass you can have TRV's on every radiator.

Thanks - yeah, I do know that, and there are (for some reason) several rads in the house which have no TRV fitted, eg in the kitchen. In previous houses I've lived in, there's been one (is it called a heatsink?) in maybe the bathroom or hall.

This seems to be an extra feature, and I'm just wondering why...

 

[Roger465]

Hope you said please in your letter to Santa.

Fortunately, Santa here in N Ireland is called "The Housing Executive", and gives you lots of money for free to improve your heating & insulation

 

[chrisw99]

I think some of the newer boilers have something built in to prevent needing 1 radiator to be TRV-less. We've just had a combi installed, and every radiator in the house has a TRV.

I'll still leave the hall radiator TRV turned up to max just in case...

 

[JohnD]

Do you mean you haven't got a room stat?

 

[Roger465]

Do you mean you haven't got a room stat?

That's right, I haven't. And I realise it would be much better to have one, and they'll probably pay for it - only thing is, the living room (where I spend my time) has textured wallpaper which is no long available, and which I quite like, so I don't fancy them digging a channel in the plaster for the wiring to fit one

 

[jackthom]

Then a battery operated wireless thermostat would fit the bill.

 

[Roger465]

Then a battery operated wireless thermostat would fit the bill.

Thanks, didn't realise such things were available... I wonder how good their transmitter is at getting through several walls... of course, the boiler is at the diagonally opposite end of this quite large bungalow, with potentially about 4 walls to get through

 

[jackthom]

All you can ever do is give it a try.
They’re pretty good and you can experiment with the location of the room thermostat before finally screwing it to a wall.
In difficult cases it may also be possible to mount the receiver somewhere a bit closer and still hide it’s wiring back to the boiler.