Grant 26e Oil Boiler goodwill please, no hot water

[Stevieboyfoote]

Dear Comrades, this forum has helped me many times before as a browser but now I need to post, fingers crossed someone kind will share their knowledge.

I am not too bad on plumbing and installed my Grant 26e myself about 7 years ago and apart from the odd service I have always been able to change parts and fault find but now I am stuck.
Recently DHW topped working but CH fine. If DHW 'on' burner would not fire and overheat light would come on, found the hot water water pump was faulty and installed a new one.
Still the same, changed boiler temp sensor and burner now fires when DHW switched to constant but no hot water and heat exchanger stone cold.

Research said to check divertor valve yet but I can't find one.
I am keen to continue but am at the end of my knowledge.
Can anyone help me please.

Thank you in anticipation

Steve

 

[MickyP10]

Still sounds like pump. Is it getting power/spinning when DHW is on?

 

[Stevieboyfoote]

Hi, pump was dead, I took it out tested on bench with mains. Replaced with new which is now running, I also bleed it through centre screw. For my info is the pump after the heat exchanger as that is stone cold?
Regards

Steve

 

[Exedon]

First your research was crap no diverter on grants they use 2 pumps,
The one bottom right is hot water the one on top boiler heating.
Use extreme care venting heating pump most common cause of board failure is careless venting that pump.

 

[Stevieboyfoote]

Thanks, yes not good research even had my part number but it was got a grant v,3, but thank you, this was helpful..
Any ideas on the fault? and how does venting cause PCB failure, thought switches and sensors controlled dry contacts which powered the pumps?
Venting just removing air?
Any pointers appreciated please.

 

[MickyP10]

Hi, pump was dead, I took it out tested on bench with mains. Replaced with new which is now running, I also bleed it through centre screw. For my info is the pump after the heat exchanger as that is stone cold?
Regards

Steve

Did you change the correct pump? Re venting, you can splash the pcb board if not careful.

 

[Stevieboyfoote]

Thanks, I see yes, with water squirting onto PCB. Yes I changed the DHW pump. Just with a replacement from the local plumbers merchant not a grant pump.
As said the old one wouldn't run on the bench with direct mains.
Only thing noted bottom pump isolator valve didn't turn as many times as the top one.
I feel close now as burner fires with switch on and no overheat. It has been a week now without hot water so one last stab and then try to find an expert.
Is it worth a punt at a control panel?
Or any clues.

Regards Steve

 

[MickyP10]

The pump runs but is cold and the burner fires and boiler doesn't overheat? Hmmm...
Maybe one of the valves is shut or partially shut?

 

[Exedon]

Check non return valve as well as pump valve they are known to stick closed.
What pump did you fit? Grant use Wilo currently, we fit the dab evosta 3 set on constant curve 3 which is correct setting.

 

[Stevieboyfoote]

Ok, thank you everyone, sussed it, hot water back.

When I fitted the new pump which was just a general cheap pump as an emergency purchase from the local merchants, he quoted £180 for a Wilko and it wasn't in stock so sold me a £55 pump.

I noted the bottom isolator turned less than the other, in my haste I just put the new pump in and turned them back. Water came out of the bleed screw and the pump trummed away so I moved on. Today my daughter's boyfriend noted the pipe past the valve wasn't hot. We disassembled and the valve was not moving and had jammed shut. As a temp fix (it's Sunday pm) we took the centre out so it no longer works as an isolator and low and behold all now work's. CH and DHW.

Thank you sincerely for you contribution and sharing your knowledge. May I ask any problem with leaving the cheap pump in the boiler? I will change the valves so they function properly so the pump will come out again. But that is an expensive pump.

Kindest Regards

Steve

 

[ChrisJP]

Glad you were able to fix your problem. Not sure I like being referred to as a "comrade" though...

 

[Exedon]

As long as its a 6mt head pump and is set on constant curve 3 it will work.