I had to drain the water from my central heating system and since
refilling, I cannot get the combi boiler to work. I think the noise I
can hear is air preventing the pump from circulating the water.
Consequently, the boiler does not light.
The combi boiler is installed higher than the radiators on the first
floor. I've tried venting the pump but only a tiny amount of air is
expelled and not enough to fix the problem. All radiators have been
blead as well.
It's pretty cold in here right now so would appreciate any
help/suggestions people can offer.
The newer combis I've come across had automatic air bleed valves but they
Chck the install/user manual for yours. Even if it has one it may be shut or
blocked by crud.
Alt. there may be a manual bleed valve or access cap on the end of the pump.
Thanks for the info. I have found the automatic air vent but it did
look to be blocked. I've now bled the air from there (not much came
out). I'm now starting to wonder if it's not the pump spinning in air
but something else that has gone. It's an old boiler. I'm considering
I drained and refilled just last week to try and improve circulation
around the downstairs radiators. The water looked remarkably clean
despite dire warnings here about black sludge. Have to redrain etc
today to replace the cleaning chemical with inhibitor. Water
circulation has improved noticeably. Hmm, should really start now
rather than catching up on News....
Anyway, the commisioning instructions for my boiler (a Vokera Flowmatic
combi) require venting the dhw heat exchanger during filling. This is
different from the automatic air vent (which should be left open), more
like a radiator bleed valve. The boiler made a lot of gurgling noises
but didn't work at all until after I had bled this.
So could there be another bit you need to bleed?
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It's a closed system. I've tried draining the system and then
refilling, hopefully so as I drain the radiators, the air in the pump
would be dislodged but no success. I think I've had it - new boiler
Thanks to all who tried to help me with my combi problem.
Turns out the problem was air in the system had caused one of the
thermostatic switches in the boiler to trip - thereby preventing it
firing up until it was manually reset (by pressing a switch on the
back of the sensor). That was it!
It would appear I did get all of the air out of the system so the pump
was switching on but the lack of action from the burner made me think
nothing was happening.
Oh well - you live and learn. So glad I didn't give up on the boiler
and buy a new one.
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