Alpha CB24 Heating issues.....need help!

[Clint 1979]

Hello all,

My first post so go easy on me!

I have been to a customers today to replace a diverter valve on an Alpha cb24, the valve has done its job as DHW works now without having to select heating mode.
My dilemma now is that when I turn the heating on, it doesn't seem to circulate very well and the burner shuts down after 15-20 seconds, I believe the water in primary heat exchanger is getting to hot to fast and temp sensor is telling the PCB the demand for heat is satisfied.
Everything is working in sequence as it should and the yellow light blinks every 5 seconds as normal.
The flow from the boiler gets red hot but the return stays cold.....some of the rads try to warm up.
I have checked the pump and bled air from the system (the AAV is also working), I have also checked the cyclone is clear and removed the DHW flow switch and made sure the spindle is moving.

Could the problem lie with the primary heat exchanger or would that operate the over heat stat? (as it stands only the primary temp sensor is switching the burner off). No red light!
Or could the problem lie with the system pipework and rads being sludged and causing the problem?

I will be draining the system completely tomorrow and try and run some cleaner through to see if that helps.

Or am I missing something altogether that one of you guy's may have come across in the past??

NOTE: The heating has not been on all year so this problem has not come about from replacing the diverter valve.

Thank you in advance for any help you can offer.

 

[bigads28]

If the boiler goes off that quickly then there is a serious restriction at the boiler. Now if the DHW works fine and modulates with little noise the you can iliminate all of those pipes. My guess would be an isolation valve. I fairly sure the return has a filter in it, a magnet on the valve will tell you if there is magnatite in it. What was the water like?

 

[drip-dry]

If working ok on hot water mode ...main heat exchanger probably ok
Would think rads turned off,they probably did this to allow the boiler to give hot water and rads not coming on before you changed valve to correct this and are getting repaired now as winter coming

 

[Riley]

Perhaps one for the gsr only forum lads not public domain

 

[Alpha man]

Hello!!

 

[Ermintrude]

What alpha man? No way a man who just does alpha boilers

 

[gasmanrob]

Try cleaning the return filter

 

[Clint 1979]

Hi all,

Thanks bigads28 and gasmanrob for your suggestions.

I have been back today and followed your advise, the return was clear and the pipes in the boiler were heating up as to be expected, I opened all the rad valves up and TRV's to try and force a bit more circulation......and it worked!
I drained the heating system and added Fernox Cleaner and ran the boiler for a couple of hours, then drained it again, then did a cold flush followed by a hot flush and filled the system back up with added inhibitor!!

All seems to be fine now and guessing the heating system just needed to clear its throat after not being switched on for 12 months or more.

Once again thanks for your input.

Riley, this was my first post on here, I wasn't aware there was a forum for GSR users?!
I am GSR.....how do I get one of those nice shiny yellow badges next to my name??

 

[Riley]

Hi all,

Thanks bigads28 and gasmanrob for your suggestions.

I have been back today and followed your advise, the return was clear and the pipes in the boiler were heating up as to be expected, I opened all the rad valves up and TRV's to try and force a bit more circulation......and it worked!
I drained the heating system and added Fernox Cleaner and ran the boiler for a couple of hours, then drained it again, then did a cold flush followed by a hot flush and filled the system back up with added inhibitor!!

All seems to be fine now and guessing the heating system just needed to clear its throat after not being switched on for 12 months or more.

Once again thanks for your input.

Riley, this was my first post on here, I wasn't aware there was a forum for GSR users?!
I am GSR.....how do I get one of those nice shiny yellow badges next to my name??

hello mate try here.

http://www.ukplumbersforums.co.uk/g...14320-how-gain-access-private-gas-safety.html

Hopefully it'll explain all.

Stick around these here are a top bunch

 

[Clint 1979]

Thanks Riley, I will have a look.

Had a look at some of the other threads on here and seems to be the place to come if you're stumped!
It's good to have somewhere with such a wealth of experience all in one place.