boiler cuts out shortly after firing up

['aveagoJo]

Good afternoon. Any help, please?
trying all day to resolve this (and work from home)
so, I have Glow Worm condenser boiler
starts up, heats up, makes a few heavy clunking, knocking noises, then stops.
no error codes.
UPstairs U0staires next to th Boiler

 

['aveagoJo]

... sorry, got cut off there...
in addition to this description, upstairs is where the hot water tank sits in a cupboard. I have a Grundfos pump UPS 3, which installed about 2 years ago. I am pretty sure it is working but it is now making a whooshing/whirring noise whilst on. Not very loud just it normally runs silently and continuously. So I thought 'Air-lock!' and have made an attempt to resolve that - no luck. I have been in the loft and checked both tanks. Both tanks have water. Header Tank has filthy, rust coloured, cloudy water in it. Both tanks have ball cocks that work. I have bled all the radiators - no luck. i have stood and stared at the boiler for a while - no luck.
Interestingly, (for me) when I turn the system on to test it, the air release valve blows a gust (i tested this by holding a lit match above it -and it blew out!) then as the pump continues to pulsate, the air release valve sucks air.
So there you have it.
Anyone have any idea what I can to do to resolve this, before I freeze?

 

[terryplumb]

First thing to establish ,is water reaching the pump ?

 

['aveagoJo]

Hi Terry (?) Thanks.
Not sure how to do that.

 

[terryplumb]

Show us pics of the pump and pipework to and from it,as well as the air release valve you refer to.
Although the F&E tank may have water in it ,the water may not be getting into the system/ pump due to a blocked feed.

 

['aveagoJo]

 

['aveagoJo]

 

['aveagoJo]

Hope these pictures work

 

[terryplumb]

Pics are ok. To establish if water is getting from the f&e into the system ,drain water out of the system ,and see if the f&e water level drops ,ballcock opens and allows water into the f&e.
I assume if you select hot water ( no heating), the boiler does the same thing ,fires up and shuts down quickly ?

 

['aveagoJo]

Yes. Boiler reacts same way HW or CH.
So, by drain the system you mean the entire CH system?
May have to do that in the morning.

 

[terryplumb]

No ,you don't need to drain the whole system to establish if the system is filling via the F&E, but you will need to drain a few litres.
If the tank isn't clean you should clean it out before draining as you don't want any crud to get into the pipework.

 

[Johntheo5]

Can't see if the pump is on Speed1 or Speed3, IF speed3 far too high IMO at 6.4M, even speed1 at 4.2M may be a little on the high side, suggest PP2 (3.8M to 1.7M) or CP1 at a constant 3.0M. Also just ensure the pump arrow is pointing upwards.

 

['aveagoJo]

thanks John.
Yep the pump arrow is pointing upwards. Been in place for about two years and not been a problem.
I have never been sure what the correct speed should be, so thanks for your advice. I will ensure it is as you suggest.

 

['aveagoJo]

Hi terryplumb, i have drained a few litres from the system. The water level in the F&E tank has not moved.
I dread to think what this means.

 

[terryplumb]

Blocked feed from the F&E. Pumps running dry, no circulation and boiler cutting out because of it.