Switching off radiators…or not?

DVN999

Hello all,

I know this has been asked before, from searching, but I’m still struggling to fully understand what we are best doing with our current Gas CH setup. 

We have a 4 bed, Edwardian semi with a gas combi-boiler and Selus smart thermostat. The thermostat is located in the handheld control unit and we keep it in our toddler’s bedroom, as that is our only ‘critical’ room to ensure temp in. 

My question, with our current setup, is: is it worth switching off the radiators in rarely visited rooms (guest bedroom, office) or does it make little difference? As I understand it, when the boiler is demanded on by the thermostat, it’s simply on, and the number of radiators being powered doesn’t matter as, once the desired temp in toddler’s room is met, the boiler will switch off…or am I missing something (heat up times maybe)..

would really appreciate a layman description of how this stuff works so we can come up with a decent, economic method going forward..

thanks in advance!

BUFF

I wouldn't turn them off personally but if you have TRVs on the rads turn them down to 2 or even 1 (or inbetween). You will save a liitle energy, minimise chance for mould etc. 

The roomstat (& programmer) will detemine whether the boiler runs or not but it's wrong to say that the no. of radiators being powered doesn't matter. If e.g. 1/2 your radiators aren't in use then less water will be circulating through your boiler & it will have a minimum output which it can turn itself down to. This means that if the boiler's minimum output is higher than the system can emit it may start to overheat, shut itself down for a period to cool then restart & do this repeatedly "cycling" - this is inefficient & not great for boiler/system life.

N.B. if you have a TRV on the rad in your child's room set that to it's max setting & let the Salus mobile unit have full control (if you have the TRV set to close at lower temp than the Salus is set to your boiler could still be running & pumping heated water around the rest of the system when you don't need it to).

Ultrasonic

Heating rooms you don't use much more than you need will use more energy. Having TRVs in lesser used rooms set to lower temperatures is what I do.

I'd have thought it was now warm enough that you don't need your heating on at all though? I haven't had mine on all week, and not using it is definitely the ultimate way to save energy  .

Reed_Richards

You have turned off radiators so the heat load of your house is reduced so you use less power.  The return water will come back hotter and if the boiler operates at a fixed output this would cause the output water temperature to increase.  If that happens the room with the thermostat will heat up faster so it's win-win, you use less energy for less time.  Except that the effiency of your boiler could drop a little.

Your gas boiler may be more sophisticated and might modulate down when it sees the heat load is reduced.  So in that scenario you use even less power but for about the same time as with all the radiators on.  And the boiler maintains its efficiency.  

But If a room where you switch off the radiator shares an internal wall (or floor/ceiling) with the room where your thermostat resides then that room will lose heat faster so will take longer to reach the set temperature.  In this case the situation is not quite so clear-cut but I think you will still win on balance.

So turning off radiators should make a beneficial difference but exactly what will happen is not clear-cut.  

Zandoni

It’s also important that the TRV in your toddlers room is fully open otherwise it may close before the room stat is satisfied. 

Mstty

If it helps we have always set the the radiator valves to 1 in rooms.used the least and max 5 or 6 for the rooms we used regularly in previous houses. However we never did any research as to whether this was money saving but the mind says it should be.

Completely off I am not sure about as those pesky controls sometimes lock closed if left off for long periods then need a tap with the hammer or replacing.

Kim1965

BUFF said:

I wouldn't turn them off personally but if you have TRVs on the rads turn them down to 2 or even 1 (or inbetween). You will save a liitle energy, minimise chance for mould etc. 

The roomstat (& programmer) will detemine whether the boiler runs or not but it's wrong to say that the no. of radiators being powered doesn't matter. If e.g. 1/2 your radiators aren't in use then less water will be circulating through your boiler & it will have a minimum output which it can turn itself down to. This means that if the boiler's minimum output is higher than the system can emit it may start to overheat, shut itself down for a period to cool then restart & do this repeatedly "cycling" - this is inefficient & not great for boiler/system life.

N.B. if you have a TRV on the rad in your child's room set that to it's max setting & let the Salus mobile unit have full control (if you have the TRV set to close at lower temp than the Salus is set to your boiler could still be running & pumping heated water around the rest of the system when you don't need it to).

Disagree with this. 
If your boiler is modern (less than 15 yrs old) its min gas rate could be 4 kw, equivalent to 4 medium rads. All modern gas boilers have modulating gas valves/ condensing boilers have modulating fans their speed controls tge imput of gas on "forced draft boiler". It wont overheat. 

Kim1965

Leave the thermostat in the hall or room Without a trv. You need one rad on a normal valve to act as a bypass. All other rooms on trvs. Shut off the ones you dont need, save money. 
 This is my job

Ultrasonic

Kim1965 said:

Leave the thermostat in the hall or room Without a trv. You need one rad on a normal valve to act as a bypass. All other rooms on trvs. Shut off the ones you dont need, save money. 
 This is my job

Please could you explain why anyone needs a radiator without a TRV? My bet is most reasonably modern homes don't have one and it's not obvious to me why it would be necessary?

Zandoni

Ultrasonic said:

Kim1965 said:

Leave the thermostat in the hall or room Without a trv. You need one rad on a normal valve to act as a bypass. All other rooms on trvs. Shut off the ones you dont need, save money. 
 This is my job

Please could you explain why anyone needs a radiator without a TRV? My bet is most reasonably modern homes don't have one and it's not obvious to me why it would be necessary?

There should always be one without because all the TRVs might shut down at once and the water needs to circulate if the boiler is firing. It’s good practice to use the one where the room stat is, although the bathroom is commonly used.

Reed_Richards

Actually, a well-plumbed central heating system should have a differential bypass valve to cope with the situation when all the TRVs shut down.  But many do not incorporate this safety feature.