Can I turn down the central heating temperature on combi boiler if I have TRVs?

[sjws1888]

Hi,
I've got a combi boiler. I was thinking of turning down the temperature of the heating on the boiler (i.e. on the boiler itself not the temperature on the thermostat). Reading up on this it sounds like setting this as low as possible is the best option in terms of reducing gas usage - to try and avoid a ridiculous bill this winter. An example would be section 4 of this:

Lower the flow temperature on your boiler to save ££

A recent report found that turning Rgas boiler can save around 6-8% on your gas bills. We show you how.

www.theheatinghub.co.uk

So I was thinking I'll do that, however I've been told that if you've got TRVs on your radiators, which I do, then you should have the central heating temperature on a combi boiler turned all the way up.
Is this correct? Do TRVs mean you need to have the temperature turned right up on the boiler. To be clear again, this is referring to the central heating temperature set on the boiler itself, NOT the temperature on the thermostat.

Cheers

 

[Mr Chibs]

I'll be interested to see what the bods on here recommend... I'm running my boiler on 1/3 heat setting think around 50°C this is feeding house radiators and and UFH room. I have TRV's on all but one of the radiators.

I seem to remember reading modern combi's are more efficient 'low and slow' again don't know if this is correct, but having the boiler really hot and using TRV's to limit the heat, seems to me a bit backward... but I stand to be corrected.

 

[sjws1888]

having the boiler really hot and using TRV's to limit the heat, seems to me a bit backward... but I stand to be corrected.

Yes thats exactly what I thought. Given the gas price rises that are coming, if it true that TRVs require the temperature on the boiler to be turned right up then I might just remove them all and replace with traditional valves so that I can turn the boiler temp down. But let's see if anyone in the know on here can shed a bit more light on it

 

[boringoldcodger]

The PM programme on Radio 4 has been talking about this and, as long as you've got a condensing boiler, they were recommending a Flow (i.e. as the water leaves the boiler) temperature of about 60C. they seemed to be saying that that's a setting of about 3 on a Worcester Bosch boiler on the CH circuit (the dial with a radiator symbol).

 

[sjws1888]

The PM programme on Radio 4 has been talking about this

Thanks - can you recall whether they mentioned TRVs in the programme you heard? specifically whether you can turn the temperature down if you've got TRVs?

 

[muggles]

The presence or lack of TRVs on the system makes absolutely no difference. For best efficiency, your boiler thermostat should be turned down as low as it can possibly go whilst still keeping your home at a comfortable temperature

 

[Mr Chibs]

Boiler thermostat (room) or boiler temperature?

 

[muggles]

Boiler thermostat, not room thermostat (although turning down your room thermostat and putting a pullover on also helps a lot with saving energy)

 

[Madrab]

Modern radiators are designed to run at ~ 70deg and they would normally be sized for the space they serve at that temp level, for the sake of heat loss calcs.

When dropping to 50Deg to say satisfy UFH then the radiators would then need to increased in size to accomodate the drop in overall output to maintain the heat loss. As suggested though it's all down to comfort and if you can run the flow temps @ 50deg and you are still happy with the room temps served by the rads then of course, run it cooler as you will save energy.

As an example - 4 dbl bedrooms + open access attic room - I have overlaid UFH downstairs and CH system runs at ~ 50Deg - due to the fact that the UFH also helps to heat the upstairs space due to convection, then the house is more than warm enough @ that temp - currently saved over £150 on last years energy costs 8 months in.

They say that dropping the stat by 1deg can save £100 on an average yearly bill.

 

[Madrab]

TRVs require the temperature on the boiler to be turned right up

TRV's work by sensing the air temp and closing down the valve when it reaches the desired temp setting, nothing really to do with the CH flow temp directly.

 

[Servotech]

Running your condensing boiler on a lower temperature will mean the boiler runs more in the economy condensing mode than it normally would, thus it could indeed save you some money.
The snag with this is that your radiators will never supply enough heat to allow the air to heat up enough to reach the recommended room temperatures that they were designed to do so.
Hence, the TRVs and room thermostat and any other economic devices fitted will become redundant.

However, with the coming economic crisis very few people will be able to heat their homes to these said temperatures anyway!

 

[Mr Chibs]

Running your condensing boiler on a lower temperature will mean the boiler runs more in the economy condensing mode than it normally would, thus it could indeed save you some money.
The snag with this is that your radiators will never supply enough heat to allow the air to heat up enough to reach the recommended room temperatures that they were designed to do so.
Hence, the TRVs and room thermostat and any other economic devices fitted will become redundant.

However, with the coming economic crisis very few people will be able to heat their homes to these said temperatures anyway!

Thanks for these updates.

I supplement heat in my lounge with a wood burner, so the low running is not a problem.
I will concede that most TRV's are then set to max, to be fair with good insulation the thermostat does operate properly and turns off when required.

I let the UFH sort its self out, and it comes on/off as and when to keep the temp constant... and use fallback temp for the small hours.

 

[boringoldcodger]

Thanks - can you recall whether they mentioned TRVs in the programme you heard? specifically whether you can turn the temperature down if you've got TRVs?

Apologies, I've been away from t'internet. Yes they were clear that this is irrespective of any other thermostats (room or TRV), I expect you've got this message from the others well before now.

 

[sjws1888]

Thanks to everyone who replied. So it sounds like there is no problem with turning the CH temp down on combi boiler if you've got TRVs, which is good. I've turned mine down now. We'll see how how it goes when winter arrives

Cheers

 

[Mr Chibs]

Thanks to everyone who replied. So it sounds like there is no problem with turning the CH temp down on combi boiler if you've got TRVs, which is good. I've turned mine down now. We'll see how how it goes when winter arrives

Cheers

More importantly, when will you be turning it on... October is the minimum for me.