Our house has a radiator in the kitchen that, I assume, is the one that has to be left on (it’s an old CH system, and it’s the only one without a thermostat valve wotsit)

The thing is, the kitchen also contains the boiler and the oven, both of which are similarly old and pump out quite a lot of heat between them. Consequently, the kitchen is roasting.

If I turn the kitchen radiator off, but make sure one of the other radiators is on all the time, will that be okay?

Yes. You can normally get caps for TRVs to ensure they’re open all the time. When I re-jigged our heating the always open rad was moved from the kitchen to the bathroom.

Smashing, ta. I’ll turn the lounge on all the way up, as it’s always freezing in there.

Or maybe it just feels freezing after walking out of the kitchen…

Yup, you can either do that or plumb in a bypass which removes the need altogether.

Our always on is right next to the boiler in the utility room. Works quite well for us as we hang clothes up to dry in there and it’s a good place to put my cycling shoes when they’re wet.

Yes, turn another one on, be aware of the risk that unless you lock another one open then someone else might turn it off and then you could cause an issue. I do not think you should take squirrel kings advice about plumbing in a bypass. I may be wrong but as I understand it the need for an always open rad is to allow the boiler to cool itself when it is making (or has made) hot water. If you plumb in a bypass then this might not provide enough cooling for the boiler.

Toys 19 the bathroom rad / towel rail is normally fully open so there shouldn’t be a problem .

Cheesybeanz, if you read the OP he states that the only one left open is the one in the kitchen..

When you say old system you mean pre combi – Have yu got a hot water tank and zone valves in the system ?

It may well be that the always on rad is plumbed in before the zone valves.

If it is and you change the trv from the living room rad.. You will be dead ending your system when the heating goes off and the pump will continue to either pump water round for ages trying to cool it down or if it cant find a path over pressure

Check your pipe work is the only way to be sure really.

Remove the head and the TRV will be always on.
Spiky pin may then be exposed though but can’t be switched off.

A bypass is perfectly acceptable since the boiler should control according to the return temperature, that’s why even a shitty old Baxi that fell off the ark has a thermostat. The hot water circuit is independent of the central heating circuit so yes, you are wrong.

be aware of the risk that unless you lock another one open then someone else might turn it off and then you could cause an issue.

That would involve my wife turning a radiator down. That, I can categorically state, is never going to happen.

When you say old system you mean pre combi – Have yu got a hot water tank and zone valves in the system ?

I mean the boilers from the late 90’s and the rest of heating system is from the early eighties. We have a hot water tank, I’ve no idea about whether we have zoning valves, or indeed what they are.

The boiler’s going to be replaced in the next couple of years, but for now it lives on.

On the subject of TRVs, are they easy to replace? One of them has, I assume, a sticky valve, as every so often the radiator bangs like a bugger (it sounds like a badly-balanced washing machine on spin cycle). A slight twiddle of the TRV and the banging disappears.

A bypass is perfectly acceptable since the boiler should control according to the return temperature, that’s why even a shitty old Baxi that fell off the ark has a thermostat. The hot water circuit is independent of the central heating circuit so yes, you are wrong.

Bear to the forum, paging Bear.

The way combis work (and some older boilers) is that when the boiler heats up to make instant hot water it (the boiler) gets hot. You turn the tap off and the boiler still has lots of heat so it needs to dump that heat and uses the one mandatory open radiator to cool the boiler. The hot water circuit and the heating circuit use the same heat exchanger to get hot from the boiler. I think its called a calorifier. I have 4 properties all had new central heating installed since 1999 and all have an open radiator for this purpose.

I think trail-rat agrees with toys19

You will be dead ending your system when the heating goes off and the pump will continue to either pump water round for ages trying to cool it down or if it cant find a path over pressure

I think if you do not provide enough cooling capacity for your boiler through on of these rads, ie bypassing it as you reccomend, then you can damage the boiler.

The hot water circuit is independent of the central heating circuit so yes, you are wrong.

ime of S type and combis – this is not the case.

My S type the boiler output was split to the rads and the hot water pipe work via zone valves + a dump radiator pre zone valves so the heat could be dumped.

my combi must have the temperature drop between outlet and inlet from 70(nominal) – 83 max – to below 55 for efficiency reasons and when my hot waters been on and i shut it down – as above it dumps the exchanger heat into the heating system so i have a dump radiator.

all im saying is make sure if your system is configured as such you are not trying to have a dump radiator AFTER your zone valves as it will have no benifit at all and you risk damage.

Bypass radiator or bypass valve for 3 reasons but not all may apply to all systems depending upon the boiler control/age/install (ie gravity installation)

To maintain minimum flow rate.
To ensure pump not pumping against a dead end.
To allow pump to run on to dissipate heat from boiler after heating or hot water generation is finished in either a combi or a Y/S plan system.

all im saying is make sure if your system is configured as such you are not trying to have a dump radiator AFTER your zone valves as it will have no benifit at all and you risk damage.

And how would I check this?

I believe if the system was installed with an always open rad then it might be telling you something..

look for zone valves on your pipe work.

(the silver boxes)

– your dump radiator pipes will come off the feed prior to the zone valve feeding your heating system.

While the OP has mentioned TRVs and presumably is buying a new one

Would you guys be so kind as to recommend the a go to TRV for both him and myself.

Do they all do the same thing …. whats the difference from the £6 ones in screwfix to the £20 ones.

Or do you have a better source ?

Ta

Can’t remember where I got my info but if enough people say so I’ll concede it could be the case I’m wrong here. I know for my system it’s possible (with a relief in the bypass) but wouldn’t claim it to work for all systems.

I thought zones were more of a specialist thing rather than the norm anyway?

I replaced all my TRV’s with Danfoss C2’s, seemed to have a good rep.

Ro5ey – the cheapy screwfix TRV’s work fine – look a bit like a Salus copy to me.