Lowering temperature of water circulating through radiators. Will it save money?

Helen28

The temperature of the water circulating through the radiators is 60 deg C and during the day the boiler comes on every 30 minutes and runs for 10 minutes to maintain the temperature set on the thermostat.

The temperature of the water exiting the radiators is low enough to make the boiler work in condensing mode.

If I reduce the temperature to say, 50 deg C, the boiler still comes on every 30 minutes but then runs for 15 minutes to retain the same thermostic temperature am I actually saving any gas?

Also when set at 60 deg C it takes 1 hour to reach room temperature when the boiler has been off overnight but it take 1 hour 30 minutes when the boiler is set at 50 deg C.

MWT

I would add a few meter readings to check the actual consumption, as from the sound of it you have a fairly modern boiler which means it will probably be modulating the burn rate so it isn't just 'on' or 'off' which means you can't just look at the running for 15 mins vs 10 mins and say that 10 mins is better.

_Jem_

Lower the temperature and it will take longer to heat the home up, increasing the temperature warms faster but cost a bit more, I think it all depends on how well your house is insulated, I was in one house where it would take  it forever to warm up so I had to have the temperature on the boiler high. 

Petriix

There almost certainly is an optimal radiator temperature which will be unique to your particular home. It will be very hard to measure or calculate because of the number of variables; no two days are the same, doors get opened for different durations etc..

I suspect that it will mostly come down to the most efficient temperature for the boiler. You may also have an option to specify the minimum on time with your heating controller (mine does, set to 2 minutes).

I suspect that the savings would pale into insignificance in comparison to just turning the main room thermostat down a bit and wearing an extra layer.

matelodave

You really need to check the gas consumption taking into account the outside temperature as well. You may find that a longer running time with the boiler mostly in condensing mode might be cheaper than the shorter run time with the boiler flogging away.

 As other have said it's a situation that is actually unique to your house, your boiler and your lifestyle. Some people want to heat the house quickly and others, especially those who may be at home all day, would be happy just to keep it up to temperature all day and aren't bothered about long reheat times.
We run our heat pump at around 35 degrees, which suits us as we are at home all day and it runs 24/7 but if we let the place get stone cold it takes around 36 hour to reheat unless we tun up the flow temperature

RelievedSheff

We have ours set low to make sure that the boiler gets into condensing mode. It takes a bit longer to heat the house but we just set the timer to come on a bit sooner so that the house is nice and warm when we get home.

As others have said it depends on your individual circumstances. What works for one house won't work for another. Our house is a 1 year old really well insulated property that takes very little heating so having the boiler temperature set low works in this house. Our last house a 1930's semi took more heating so the boiler temperature was always set quite high.

oldagetraveller1

I can't remember where I saw it. A plumber/heating installer advised that the return temperature to the boiler(condensing) was the important thing for it to work at it's most efficient.

I think that was 56ishdeg.C?

I have my boiler thermostat set for the outlet at 74deg.C to obtain that return temp.. That will be different individually though, number of rads. in use etc..

Plus a properly balanced system.

Cardew

There is no 'one size fits all' temperature for the best setting. More sophiticated CH systems have a weather compensating control - an ouside monitor which adjusts the boiler water temperature.

With a condensing boiler(most are these days) a lower temperature is generally more efficient but, as stated above, the property takes longer to heat up.

st999

So if the property takes longer to heat up that means the boiler will be on longer so I would think you wouldn't save much money.

Cardew

st999 said:

So if the property takes longer to heat up that means the boiler will be on longer so I would think you wouldn't save much money.

Using that logic, if you were to drive 100 miles in 1 hour you would use less fuel than taking 2 hours for the same journey!!

Actually it doesn't mean the boiler is working(i.e. using fuel) all the time during the longer period to heat the house. Heating the water to, say, 40C takes the boiler less time than heating the water to, say, 60C. Also the boiler modulates i.e  has a lower output for lower temperatures.

RelievedSheff

st999 said:

So if the property takes longer to heat up that means the boiler will be on longer so I would think you wouldn't save much money.

No not with a modern condensing boiler as the boiler won't be fired up using gas for the whole period.