Boiler replacement

[nairb999]

Recently replaced my 25year old Potterton Prima F boiler with a heat only Baxi 619 Heat. From day 1 had air in upstairs radiators. The boiler was a straight replacement. It is an open vented system servicing 15 radiators on 2 floors. Configuration is Boiler Vent Feed Pump. Is it fair to say the only difference in the 2 boilers is the Baxi is a condensing boiler. The installers did not rebalance the radiators because they had a hell of a time trying to fill the system due to airlocks and the boiler kept tripping out. Eventually backfilled the system and after bleeding radiators all heated up satisfactorily. Would it help if the radiators were rebalanced? Got the installers back and they thought the system could be sucking air through the vent pipe although only days earlier system had no problem with air ingress. They suggested extending the vent pipe into the water. That did not help.

Can anybody assist me on this issue?

 

[cross thread]

Try turning pump speed down and upload a photo of boiler,pump and cold feed setup.

 

[nairb999]

Pump speed lowered to 2.5 with no improvement

 

[ianmcd]

Is that a new pump just installed ?

 

[nairb999]

No 8 years old. Gr8 pump very quiet

 

[Stadan20]

Did they do a powerflush ? If so they probably didn't neutralise the system after. If you have a magnet handy place it on the second tee ( closest to the pump) if it attracts its probably a blocked cold feed .

 

[nairb999]

Tested with a magnet. No issues

 

[cross thread]

What direction is the pump facing? Should be down with that set up

 

[nairb999]

Yes it is down

 

[gas112]

not by any chance mixed up the flow and return

 

[nairb999]

The previous boiler worked fine for 25 years. Boiler vent feed pump set up

 

[gas112]

The previous boiler worked fine for 25 years. Boiler vent feed pump set up

which is why they have possibly crossed the pipes by the boiler
"kept tripping out" is an indication of this

 

[nairb999]

This is the set up

 

[ianmcd]

This is the set up

That is exactly what has happened, they have reversed the flow and returns, as you can see attached on the prima F the flow was on the left and the return on the right, your new boiler is the wrong way round

 

[nairb999]

Jesus. Bloody idiots. Thankyou so much Ian. Could that have had any adverse effects on the boiler?