Potterton performa 28i not firing after fitting EV

[Tommythrostle]

Hi,
The expansion vessel in my Potterton performa 28i has failed, water coming out of schraeder valve. Reading the very helpful advice on this forum I decided to fit an external expansion vessel teed off CH return with 15mm pipe into 3/4 female. The vessel is located beside the boiler so bottom of vessel is approx in line with top of Boiler.

The pipe work enters at bottom of vessel and schraeder is at top. According to the label it is upside down. It had 1.3 bar pre charge. Prior to fitting vessel boiler worked fine unfortunately now the burner is not igniting and the low pressure fault / pump fault light is flashing, the pump is spinning and becoming warm and the guage shows the pressure as 1.5 bar, is an air lock in boiler causing this ? The boiler is making unusual sounds - grinding gurgling sounds as if trying to push water through. I recently changed a small rad 600x600 and fitted an angled valve with drain cock, the property in question is a flat with a total of 5 rads. I've spent several hours and am totally flummoxed, all advice greatly appreciated.

Thanks
Tommy

 

[Agile]

The EXV seems correctly fitted to me with air valve at the top.

I did not think that model had a LP water switch.

Its probably just some air in the system.

Running it on and off a few times might cure it however you might need professional help.

Tony

 

[hertsboilers]

Central heating pressure differential microswith is not activated while pump is running. Bleed air from inside the boiler.

 

[Tommythrostle]

Wow, super quick replies.

Thank you very much guys. Whats the best way to bleed air from combi boiler ? I've tried the vent above pump, would it be worth my while loosening the screw on the pump ?

 

[hertsboilers]

1. Auto air vent.

2. Pump bleeding screw. Be careful not wet the circuit board.

3. As Tony said, start and stop boiler.

By the way, didi you check the pump is running?

 

[Agile]

The auto air vent is meant to do the job.

The big screw on the pump might help.

Alternating between heat and DHW will help a lot.

Tony

 

[Tommythrostle]

Air came out of the AAV for about 5 secs, I believe the pump is working as it is vibrating when I place my hand on it and it's quite warm

 

[Tommythrostle]

Really appreciate the advice, shall try suggestions tomorrow. Should I say later today.

 

[Tommythrostle]

Switched between DHW and CH a few times, messed about with Expansion vessel pressure, blasted water through system by opening filling loop and expelling from drain cock and most importantly opened air vent with boiler running, quite a bit of air was expelled.

Job done, Boiler humming away doing the necessary.

Big Kudos to Tony and HertsBoilers, Thank you very much guys wouldn't have been possible without your assistance.

 

[petit_pablo]

If fitting a remote vessel on these pottertons you wil get a stack of air trapped in the original expansion vessel when refilling.

As the OP has done, perseverance will shift it eventually