Best temperature for Condensing Boiler

mawallace

We have had a condensing boiler fitted. What temperature should we have the boiler thermostat set at? The hot water cylinder is set at 60 degrees.

What about when the hot water radiators are on?

Ectophile

It really needs to be over 60 degrees so that the hot water cylinder reaches the desired temperature. Otherwise you could come down with legionnaires' disease (to be honest, that's very rare in a private home).

In addition, set it too cool and your home will never warm up in cold weather. You'll just get vaguely warm radiators.

Given all the above, the cooler the better. The condensing bit works better if the water returning to the boiler is cold enough to condense the exhaust gases. Crank it up too hot and it becomes less efficient.

firefox1956

Does the instruction book not deal with this ??
HTH

mawallace

Nope and when I phoned Baxi they said they did not have a recommendation

Cardew

As indicated above you need the water returning to the boiler to be 55C(the dew point) or below for the boiler to condense and thus operate in its most efficient mode.

How do you achieve that? - with great difficulty?

Essentially you need to run the boiler temperature as low as possible, but obviously sufficiently high to warm your house. The problem is that the heating load varies as radiators are switched on and off - either by the TRV or a human!

Also a temperature of 60C might be adequate on a mild winter day but inadequate when it is really cold. More sophisticated boilers cater for this with a weather compensating control.

This is an interesting blog:

http://www.yougen.co.uk/blog-entry/1946/Is+your+condensing+boiler+actually+condensing'3F/

Chrishazle

Thanks Cardew, we've just had a condensing boiler installed a week ago, noticed that the exhaust has loads of vapour - which the old Baxi non-condensing did not. However, having read your post, the installer had set the boiler temp at about 80C, so I've turned it down to about 70C to see what happens! Hot water temp is set to 58C - tried 60C, found it just a little too hot, 58C is just right.