On what temperature do you put your boiler on?

[Golan]

What is the best temperature to keep the boiler on? What do you keep it on?The maximum 82 degree or 60-65? High temp = more gas but lees time to heat the house. So how do you find it best to set?

[Roger Cain]

Whatever gives the max. temperature which you need for domestic hot water. Mine is at about 70C - anything more than that and the wife complains that it is burning her hands.

[visionset]

I have the heating on near max ~70 (75 max) I have the tap water on ~50 since it is very hard water and it keeps the scale down. Combi - I get to choose both.

[Ron Lowe]

I get to choose both, too, without a combi.

The boiler stat determines the primary ( Central Heating Loop ) temperature, the room stats / zone valves and TRVs determine the room temperature, and the tank stat and associated zone valve control the Domestic Hot Water temperature.

This is not an uncommon configuration.

[Doctor Drivel]

You should install a cylinder thermostat then.

[Dave Plowman (News)]

Assuming a non condenser non combi with control over the hot water temperature via a cylinder stat and valve, maximum.

[The Natural Philosopher]

? I have a tank stat which takes care of that..as long as the boiler flow water is ABOVE the desired temp, its all OK.

[The Natural Philosopher]

as will any other system with a hot water tank that has a stat on it.

You turn the temp up enough to get the heat output you need. lower is more efficient at fuel use, higher is more efficient at heating the house!

[Michael Chare]

If there is nothing in the instruction manual you could ask the manufacturer. FWIW the manual for my boiler suggests a high setting for winter when the C/H is on and a low setting for summer when just the H/W is being heated.

Clearly if you use a low setting you limit the amount of heat the boiler can output and the speed which it can raise the house temperature (and reheat the H/W).

[Doctor Drivel]

Nope. He has full independent control of CH & DHW. With a cylinder stat the CH rad temperatures can't be less than what the DHW requires. Unless you put in a diverter system (easy to do or convert from a non-diverter system) with a pipe stat on the boiler flow or return for CH rad temp, controlling the boilers temp. Then the boiler can be left on full meaning a fast warm up fro CH.

[Doctor Drivel]

Not quite. A boiler raises the temperature of the x degrees and n water flow through boiler. Let's say it raises the water temp 35C. On warm up from cold, the water may be returning to the boiler at 17C. That means the boiler will be producing 52C of flow temperature and it may be set to 65C. Until the return reaches 30C the boiler keeps firing. Up until this point it heats up from cold at the same rate as if the boiler is set to 82C.

[Christian McArdle]

This might not be safe, as you could easily run into leggionaires' problems. You should really store water at about 60C (or more) and use a thermostatic mixing valve if you want cooler water. Even 55C would be significantly safer than 50C.

Christian.

[Christian McArdle]

Not necessarily. That depends on whether the radiators can emit enough energy at the lower temperature to use all the boiler's capacity.

Christian.

[Doctor Drivel]

Yep.