Using one radiator...is it worth it?

Lalaladybird

Can anyone tell me if this saves money or wastes it please. Last night I set the thermostat to 18 but switched off all the radiators except the one in my daughter's room so that she would be warm enough (she's only 1). So DH and me were in a freezing living room snuggled under blankets and hot water bottles and the same in our bedroom all night Brrr!

Does it mean that the one radiator that is on is trying to bring the temp of the whole flat upto 18 therefore using loads of gas or will it just bring that one room up to 18 then switch off???

PasturesNew

I don't know the real answer, but I had a house with 12 rooms and 13 radiators. It was a 130 year old (cold) house. All of the pipes were exposed (so there was heat loss there) and on the ground floor the pipes ran under the floorboards in a 4' cold void under the house (massive heat loss there).

I used to have just one radiator on in the room I was in. Then one winter the boiler broke. I had to use electric fires. From my meter readings/bills it certainly seemed like I could run the one radiator cheaper than the one electric fires.

stilernin

I guess that the heating will be trying to get the temperature of the area around the thermatat up to 18deg. So if it is in your hallway the system will continue to run until the hall gets up to temperature.

Keeping the doors of unused rooms closed will help of course.

There will be someone more knowledgeable along soon I expect

Magentasue

I would ask this on the Gas and Elec board. I'm sure it's come up before and I thought the answer was not to turn radiators off but to turn them down in unused rooms. Not sure though.

I can't see that it would cost much more to have the radiator in the sitting room on.

WestonDave

The system will continue to run until the area around the main thermostat reaches 18C. This has a number of implications depending on your system. If your daughters room has a thermostatic valve (bigger and with numbers on it) then when her room reaches whatever temperature that is set to then that radiator will turn off (that may or may not be 18C). If it has a plain valve (small with no numbers) then because the thermostat never gets to 18C the system will keep supplying that radiator with heat and could cause the room to get overheated (which is as big a problem for small children as cold). If you still have plain valves (unlikely but worth making the point about overheating!) get them changed - a reputable engineer can do this pretty cheaply.

If you have thermostatic valves (TRV's) there is another potential problem. The system will keep trying to get the thermostat up to 18C, however at some point your daughters room will be warm enough to turn off and you now have no radiators on the system accepting hot water. Some systems really don't like this - it is effectively a short circuit as the boiler heats water, sends it out round the pipes and gets it straight back - I have a feeling in some older systems its worse as there simply isn't anywhere for it to go if all the radiators are off. Most systems have at least one plain valve to prevent all radiators being switched out by TRV's when the main thermostat is still demanding heat from the boiler.

The other thing you need to balance is a sensible level of heat in the house to prevent damp and mould with saving money on energy bills. These last couple of nights have been as cold as many we will see this winter - having the heating off is taking money saving to the extreme. Cold rooms with you breathing out warm moist air will lead to water condensing out onto cold wall surfaces - unless you are going round in the mornings wiping down your bedroom walls, that water will hang around and breed mould, which in turn will spread spores which can make some people very unwell. Saving money on heating is wise, but not if you have to replace furnishings and spend a fortune on cold cures so look after yourself!

Greatgimp

That's a good post from WestonDave. Lots of well thought out information, must have taken ages to write that out correctly - well done WestonDave and thanks!

Penelope_Penguin

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Cardew

WestonDave wrote: »

The system will continue to run until the area around the main thermostat reaches 18C. This has a number of implications depending on your system. If your daughters room has a thermostatic valve (bigger and with numbers on it) then when her room reaches whatever temperature that is set to then that radiator will turn off (that may or may not be 18C). If it has a plain valve (small with no numbers) then because the thermostat never gets to 18C the system will keep supplying that radiator with heat and could cause the room to get overheated (which is as big a problem for small children as cold). If you still have plain valves (unlikely but worth making the point about overheating!) get them changed - a reputable engineer can do this pretty cheaply.

If you have thermostatic valves (TRV's) there is another potential problem. The system will keep trying to get the thermostat up to 18C, however at some point your daughters room will be warm enough to turn off and you now have no radiators on the system accepting hot water. Some systems really don't like this - it is effectively a short circuit as the boiler heats water, sends it out round the pipes and gets it straight back - I have a feeling in some older systems its worse as there simply isn't anywhere for it to go if all the radiators are off. Most systems have at least one plain valve to prevent all radiators being switched out by TRV's when the main thermostat is still demanding heat from the boiler.

The other thing you need to balance is a sensible level of heat in the house to prevent damp and mould with saving money on energy bills. These last couple of nights have been as cold as many we will see this winter - having the heating off is taking money saving to the extreme. Cold rooms with you breathing out warm moist air will lead to water condensing out onto cold wall surfaces - unless you are going round in the mornings wiping down your bedroom walls, that water will hang around and breed mould, which in turn will spread spores which can make some people very unwell. Saving money on heating is wise, but not if you have to replace furnishings and spend a fortune on cold cures so look after yourself!

Dave,
Excellent post on heating.

On the subject of TRVs, it was certainly the case that older CH systems required one radiator to not have a TRV fitted for the reasons you explain.

However most modern(last 20 years) have a Automatic bypass(pressure balancing) valve(ABV) so it is OK to have TRVs on all radiators - I mention that in case someone gets worried.

I am not sure I agree with your justification to keep up heating levels to prevent formation of mould. The warmer the air, the higher the water content it can hold.
The key to prevening mould is ventilation and keeping the humidity level down. If your house does have a problem with mould then the solution is to get a dehumidifyer.

In UK most mould problems occur in the bathroom, even if that is a warm room.

Mould is a far more serious problem in tropical climates where rooms without airconditioning to cool them are very warm.

BallandChain

We have an electrical CH system and it is costing a fortune to run 2 radiators. I doubt it will be cost efficient to have all the radiators on. Maybe someone can prove me wrong?

louiser123

i thought (maybe stupidly) that it makes no difference wether 1 radiator is on or 2, or the whole lot, im sure i got told this by a BG engineer. the boiler will heat the room to the required temp then the radiators cut off, surley the hot water is moving around the system to heat the radiators so by turning some off you would be wasting the opportunity to heat those rooms?? thw water will flow past the off radiators to the one thats on so surley it makes sense to heat the whole house and cant cost more, if it does it shouldnt be a vast amount?? i think i might have confused myself now as well as all you!!! lol. but in short thehot water has to pass under the off ones( just a manner of speaking) to get to the one thats on so it would make sense to have them all on and be warm. it isnt costing anymore just to let the hot water flow through the radiator thus heating the room, instead of sittin there freezing?? am i right

KimYeovil

If the hot water heats rooms on transit to it's targeted room then that heat is lost - it can not both lose it to the incidental room and then retain it for the target.

Just think - if what you suggested happened all you need do is have a very small radiator in a very small cupboard at the end of the circuit. Just heat that very small cupboard and the rest of your home gets heated for free! Fun idea but physically impossible.