Central heating problem

[plumber_UK]

Around 6 months ago we fitted a ideal heat only 30kw boiler. This was put in to replace a smaller heat only boiler as a customer was having a extension built.

The radiators heated fine until the radiators on the extension where added, Now the system is occasionally hot upstairs and luke warm downstairs. The customer has just called to say he heard gurgling and now there is no heating or hot water. this is after it working ok for the last 6 months

Jobs we have done to try rectify the problem
1.We have replaced the pump which had no affect, we then assumed that we may have had a faulty pump so replaced it again.
2.We also changed the zone valves
3.We thought it my be a blockage so replaced the heating circs upstairs and downstairs ( this may seem extreme but we thought that spending two days trying to find the blockage or spending money on a power flush was not worth it, it was far easier and quicker to replace) Anyway this still didn't work.

The only thing we have noticed was the pump slightly pumping over into the header but the header did not overflow. When we had renewed the circs every pipe was physically checked and no blockages found. it has apparently done this for years

has anyone any idea what could be wrong ?

 

[ShaunCorbs]

did you re pipe to every rad up and down? or just the main circuits

 

[REDSAW]

apparently done this for years........6 months old system?

explain?

how many dead legs on pipe run?

 

[jtsplumbing]

What size pipe runs ? small bore or micro bore, how much 22mm on runs ??

 

[Rickster123]

Is there a gate valve being used as a bypass that's been opened fully by mistake?

 

[Unregistered]

Pumping over has been an issue before the new boiler was fitted.

We re-piped just the main circs. We have had heat to every radiator so know the pipework to the radiators are ok.

There are no dead legs

 

[lame plumber]

would have been better to convert it to system boiler/sealed system, probably still the best option

 

[Unregistered]

There is a bypass gate valve I checked this and its only slightly open.
From what I can remember there is 22mm flow and return( main circs), the drops are also 22mm, 15mm up to radiators There is no micro-bore pipework.

The boiler is roughly 6m away from the cylinder and pump

 

[ShaunCorbs]

Pumping over has been an issue before the new boiler was fitted.

We re-piped just the main circs. We have had heat to every radiator so know the pipework to the radiators are ok.

There are no dead legs

is there a gate valve on the feed (to the system) if yes turn that off and does that stop the pump over if yes you got the t's in the wrong place

 

[Unregistered]

oh how i wish i had made it a sealed system. Its a job another plumber had priced up but couldn't do.

 

[plumber_UK]

We checked that the tee was in the right place.

 

[REDSAW]

pumping over taking the shortest route or airlock/ pump running dry!

 

[plumber_UK]

Pumping over taking shortest route ? do you think its circulating round the top floor radiators and up through the feed. which then means its not able to pump downstairs.