Can't get boiler to fire after draining / refilling system

[Jcls]

Hi all,

Firstly, I have an old Baxi (non-combi) system.

I am refitting a bathroom. In preparation for the later fitting of a new towel rail / radiator, I have drained down the central heating system.
I've now fitted all the new pipework and fitted valves to the end of the new radiator feed pipes (as I'm not ready to fit the rad itself until after I've tiled).
I've refilled the central heating system by 1) allowing the header tank to refill, then 2) closing off the drain valves downstairs and 3) bleeding multiple rads in the house. Then turned on the heating and hot water to check for leaks and also to make sure the new pipework holds up under pressure when hot.

Problem - the central heating / hot water control panel shows both systems on continuous with red lights to confirm they are on (or should be). I've turned the thermostat up to 30 degrees and I've confirmed that I do have a pilot light in the boiler - however the boiler is not firing up like it would normally.

Any ideas what I might have done (or not done)?

ps: I do hear a sort of humming / droning noise when I move the controller slide switch from off to continuous but that's all. I'm wondering if the pump is not primed (after the system drain) or something?

 

[leakydave]

Are you sure the boiler didn't run briefly but overheat due to lack of circulation. to protect the boiler an over heat stat may have tripped. See if you can find any reset buttons on your boiler.

 

[Jcls]

Er - no I'm not sure actually. I didn't hear it start but I suppose it might have. I've attached a picture of my boiler:

 

[leakydave]

So is the pump turning? have you bled the pump?

 

[Jcls]

I had not bled the pump. Have now though and it required several minutes bleeding too! The boiler has fired up now so I think you have solved my problem. Thanks very much! Now back to checking for leaks in my pipework...

 

[Jcls]

Think I spoke too soon. The boiler did fire up but has gone off again much too soon (and the radiators are not warm. The thermostat's still on max. I tried bleeding the pump again and giving it some gentle taps but that doesn't seem to be the problem. There is some other device to the right of the pump (see pictures, but not sure if that is something that needs bleeding also. I've switched off the system now as I'm getting worried I might damage something and I'm thinking I might have to get a plumber / heating engineer in to advise

 

[leakydave]

Does the auto air vent to the right and above the pump work?

 

[Jcls]

I'm afraid I do not know how to determine that. How do you test that? Thanks!

 

[gasmanstu72]

you'll need to get the air out that area, its no doubt air locked,
the brass body of the auto air release will unscrew, get a pair of grips on it and turn it until it can be loosened by hand, it'll be the same as bleeding a rad, you may have to do it a few times,

before that though, make sure the dust cap is loose on top

 

[FiremanT]

the brass body of the auto air release will unscrew, get a pair of grips on it and turn it until it can be loosened by hand, it'll be the same as bleeding a rad, you may have to do it a few times,

Probably correct BUT DO NOT OVERLOOSEN. If the valve comes off you will have a flood.
Or are you standing there with a thumb on the pipe?

 

[dreadnoughtheating]

the brass body of the auto air release will unscrew, get a pair of grips on it and turn it until it can be loosened by hand, it'll be the same as bleeding a rad, you may have to do it a few times,

Probably correct BUT DO NOT OVERLOOSEN. If the valve comes off you will have a flood.
Or are you standing there with a thumb on the pipe?

I love these sorts of posts, just waiting on 'that phone call', "erm, is that the emergency plumber? hello? my husband has his thumb...."

DH

 

[Jcls]

Thanks all - I did figure out eventually that the auto air release (?) was another valve that could be bled. I found that with the heating on, I could open this and air would hiss out for say 20 seconds, then I'd close it for a minute and then reopen it and it would let more air out. I basically did this for about half an hour while running to the upstairs radiators and bleeding them. Blinking exhausted now but system seems to be mostly working.

Thanks again!

 

[Jcls]

Final thought on this: why is it called an auto air release if you have to 'manually' release the air??? Crazy

 

[FiremanT]

It is automatic... but faulty.
Internally there is a lever on a "hinge", on the end of which is a float above which is a rubber seal which should seat on the orifice as the water rises, this stopping the flow.
The cap should be permanently loose, air should be dispelled, and as water appears, it should close off. I assume you are opening the cap an closing when water appears? .If you HAVE to close it manually to stop water squirting, then the seal is damaged or there is crud on the seating.

They are very easy to change, but are notorious for passing.

 

[Dean744PiN5]

because they stop working when crud and sh1te block them up, not the valves fault just a fact of the neglected systems of Britain.