Flow/return accidently swapped - Boiler only fires for 10 seconds

[Shervin182]

Hi guys, new to the forum.

Yesterday myself and the father in law had to slightly move the flow/return pipes to fit within new boxing in. We drained the system, moved the pipes and refilled it. Fired up the boiler - The radiators got hot (too hot) but the boiler was making banging noises (as though someone was inside it tapping at it with a small hammer!)

We re-assesses the pipes we'd altered and were 75% sure we'd somehow managed to swap them by accident. We turned the boiler off, re-drained the system, swapped the pipes, refilled the system and turned the boiler back on.


This time the boiler would only fire for a few seconds but no banging this time. The flow pipe coming from the boiler was red hot, but the radiators and return pipe was cold. There is also no hot water.

It's a Baxi boiler (not combi) With an unvented hot water system/cylinder.

Any help appreciated!

 

[SimonG]

Its airlocked, need to get the air out.

 

[SJB060685]

As above. If airlocked then the water cant circulate away from boiler.

 

[Shervin182]

Its airlocked, need to get the air out.

Thanks Simon, after googling it, we went ahead and followed the steps from this link below to ALL of the radiators. Plenty of air came out, seemed like it was going well but unfortunately the boiler only gets hot for a few seconds. The pump appears to continue. Some of the flow valves on the rads started getting warm but for some reason the boiler just won’t stay fired up and everything cools back down quickly.

 

[Shervin182]

Thanks Simon, after googling it, we went ahead and followed the steps from this link below to ALL of the radiators. Plenty of air came out, seemed like it was going well but unfortunately the boiler only gets hot for a few seconds. The pump appears to continue. Some of the flow valves on the rads started getting warm but for some reason the boiler just won’t stay fired up and everything cools back down quickly.

Scrap that, it’s just fired up and it heating the rads again but it’s back to banging. Seems to be heating the TrV valve with the numbers last. Is it circulating the wrong way?

 

[ShaunCorbs]

trv pipe should get hot the first but if you go in the cupboard with the cylinder the port valves should get warm first if they dont you need to swap them back