What boiler setting ?

[Maxx470]

I have a 12 radiator system fired with a Merlin oil boiler 85,000 Btu's.
What would be the best settings, the room stat is in the hall and I dont have any TRV's. I want it to be nice & warm throughout. At the moment I have the room stat set at about 21 and the dial on the boiler at 75. It goes up to 90.

Is it better to set the boiler higher & let the room stat take over ?.
I want the best heat output at the cheapest running costs.

 

[David937]

When we had our old boiler the stat on the boiler was kept at setting 3 of 4 in normal conditions and we had it at setting 4 on the very cold days.

If you want to save money then try fitting TRV's and reduce the room thermostat gradually until you find it comfortable, it's best to lower it in 0.5 degree steps over a few weeks.

To save money have the boiler off as much as possible.

There is no particular setting the boiler stat should be at, if 75 degrees heats up your house as quickly as you like it to then leave it. If you like burning hot radiators then set it at 90 degrees.

 

[Maxx470]

I think the two settings I and many others have is a bit of a lay off between each other. Because if ,
boiler is set high and room stat is set at say 25, because surely the boiler would cut off once the room stat has reached 25 but get there quicker, not hotter ?

 

[David937]

You would usually use higher boiler settings in the colder weather to compensate for the losses.

It is usually better to adjust the boiler thermostat according to the weather.

Try reducing the boiler setting and see if the house reaches the set temp in the desired time. In warmer weather use lower boiler settings and in colder weather use higher settings.

Some say it is best to run older standard efficincy boilers at the highest possible temperature but I am not really sure about that.

Higher boiler settings will result in faster warm up times and hotter radiators but usually makes no difference to the room temperature.

If you have an older mechanical thermostat that cuts out as soon as the set point has been reached, the radiators continue to give out heat which causes the temperature to go above the set point. Hotter radiators may posibly give out more heat after the thermostat has cut out the boiler.

 

[Maxx470]

now were getting somewhere David.
This is my question, is it cheaper to set the boiler higher as you said.

 

[David937]

If I gave you a simple yes or no answer, there would be too many contradicting posts.

IMHO it is cheapest to run the boiler at the lowest possible temperature.

If you have a tank that is heated by the boiler, the boiler stat must be set 10 degrees higher than the tank stat. Usually you can't get away with anything lower than 65 degrees, or else your tank won't get hot.

 

[simond]

You will experience more 'heat loss' at higher boiler temperatures.

So leave your boiler on the lower temperature needed to keep the property warm.

The best way to save heating bills is to ;

- lower your room stat by 1C
- only heat the rooms you are actually occupying to occupational temperature*
- improve insulation
- look at improving the boiler to an efficient version

*This can be achieved by heat zoning, or electronic controls, or Honeywell's new HR20 timed TRV heads.