Help needed Alpha CB50

[Kevin71]

Hi

I really need some help to understand an issue I have with my Alpha CB50 boiler.

I have had numerous engineers out, many parts replaced, lots of money paid out and still it's not working correctly. (i'm in so deep now I need to get it sorted)

The heating side of the boiler fires up and tries to heat up the system but after a short period of heating it stops. The heat generated from the boiler gets to the first and second rad on the system but the rest are cold.

This would make you think its a flow / block issue with the pipework etc but every rad has been removed drained and checked, system flushed and flow seems to be fine. If you isolate each radiator in turn it will heat up after a long period of the boiler going on off on off etc.

When looking at the boiler it seems that the flow is getting really hot and flowing through the bypass valve and back up into boiler and so the boiler is reaching temp very quickly and a small amount of heat is getting to the radiators.

My initial questions are could the bypass valve be faulty?, how does it work? and if the flow is good why is it feeding back through to the top of the return?

Finally parts replaced so far:

Pump, Diverter valve, Board, temp sensors, Pressure relief valve,

Thank you in advance for any help you may be able to give

Kevin

 

[ianmcd]

sorry to state the obvious but why not close the By-Pass then and see what happens ? you cant do any harm

 

[sloaney]

Is the return isolation valve on the boiler closed?

 

[Kevin71]

sorry to state the obvious but why not close the By-Pass then and see what happens ? you cant do any harm

The bypass valve is a complete unit (part of the boiler)connected to both the flow and return pipes below the boiler. Will be difficult to remove and not sure how to close it or remove as I expect the valve is within the fitting? Does anyone know if these are prone to fail

 

[Kevin71]

Is the return isolation valve on the boiler closed?

both isolation valves checked and working correctly.

 

[Kevin71]

Picture of valve


//www.diynot.com/network/user_album_update.php?album_id=18151

 

[Nids]

I understand this post is from several years ago but I have exactly the same issue. @Kevin71 I am hoping you will see this and confirm if you ever sorted and and if so was it the bypass manifold or something else??

I have an alpha service contract and although no parts have been changed one of their engineers blamed the main heat exchanger, I assume this was to wash their hands of an old boiler.

I think I have one last chance at getting them out but would really help to direct them with trouble shooting rather than relying on their engineers opinion.

Any help would be really appreciated!