Warmflow B70 he condensing

echo12345 · Mar 5, 2022

Just had a warmflow b70he 21kw oil fueled installed. I haven't had a condensing boiler before so please excuse the possible stupid questions.

I was under impression that when the heating is on you shouldn't here the boiler firing and there shouldn't be an almost continual flume of vapour out of the flue? That they should be maybe intermittent as these things are supposed to be more efficient?

Because at the moment it runs for about 10 mins, stops for 1-2 mins the fires up again. It will be like this all night. The old Reillo I had that the previous owner had never serviced and was in a bad state didn't even run as much.

The rads all have tvrs, there upstairs and downstairs thermostat set to 16 and 21 respectively.

5 double rads, 4 singles and 3 tiny singles in the ensuites/laundry.
All tvrs are set to 3, except the living room thermostat at 5 and bathroom at 4. The micro rads set at 2.

If anyone can reassure me that it sounds perfectly normal? The house actually feels colder than with the old boiler and I'm a bit reluctant to put thermostat up at the moment when it sounds like it's already firing constantly as it is.
Is it possible that this boiler isn't enough for the rads required?

John.g · Mar 5, 2022

The b70 appears to have a output of 18kw, A cycle time of, (10+2), 12 minutes indicates that the boiler is outputting 15.0kw, if the old boiler had the same (18kw) output then the cycling time should have been the same if the heating demand was the same.
The vapour plume shows that it is partially condensing at least (quite normal), you will hear any boiler when its firing, some are quieter than others.

SJB060685 · Mar 5, 2022

It’s a fixed rate burner so it’s output is the same every second. You will get cycling at the boiler on days that aren’t design temperature. Perhaps the new boiler is over sized or the old one undersized?
Water vapour is transparent but reflects light which gives it a whitish colour. This is a sign the boiler is condensing to a degree.

exedon2 · Mar 5, 2022

Bit difficult to comment accurately without knowing radiator heat load I assume boiler feeds a hot water cylinder as well?
From memory your boiler is set mid range at factory just below 18kw but if re jetted to a 0.6 can be set to 21kw

SJB060685 · Mar 5, 2022

Guys think of the first law of thermodynamics. Energy can neither be created nor destroyed, only transferred or transformed. If a boiler is cycling it is because it’s outputting more energy than the system can displace.