Grant boiler leak, seal oring or something else?

[Luggsey]

The on going saga of my Grant boiler problems continues!
Have replaced the Wilo CH pump and now the HW pump is rattling.
Before I had chance to change the HW pump the flow sensor cracked and leaked. Patched up and new one ready to change.
Before I got to the pump or the sensor its sprung another leak!
Its the shut off valve now, its got a fast drip from the flange as arrowed.
Before I strip it all down can someone tell me what to expect to replace in this valve? Do I need a seal/o ring or sealant?
I want to get down to the plumbers merchants for any bits I need before starting.
Cheers if you can help me out.

Paul.

 

[ShaunCorbs]

You sure it’s not coming from the front nut ?

 

[Luggsey]

You sure it’s not coming from the front nut ?

I don't think it was?
Can you strip these down to repair?
If I have to change it I will have to remove all the heat exchanger pipework as the nut is tight behind the pipework!

 

[ShaunCorbs]

You can repair them tbh best to use either a fibre washer or some loctite 577

 

[Luggsey]

You can repair them tbh best to use either a fibre washer or some loctite 577

So can I simply undo the larger nut at the back and unscrew the valve?
Cheers

 

[ShaunCorbs]

Yes but you will need to drain the boiler first

 

[Luggsey]

Yes but you will need to drain the boiler first

Thanks, boiler is drained and cw shut off, I think I need to isolate the ch pump and all thats there hopefully is in the boiler pipework and pressure vessel?
Cheers.

 

[ShaunCorbs]

If the boiler is drained you won’t need to isolate anything else

 

[exedon2]

Common fault on the grant combi having got rid of system pressure we take valve head out make everything clean few turns of loctite 55 behind flange end of problem.
Grant are aware of the problem if its still under warranty they will send you new pump valves you change them send them back with your invoice payment never more than 2 weeks.
Same thing with auto air vents that they have started fitting again on the combi and system boilers.

 

[SimonG]

Is your expansion vessel big enough?

 

[Luggsey]

Thanks all, the fibre washer had disintegrated so amazingly I had to correct replacement, done and dry. Changed the Wilo pump and the flow sensor while it was dry. Just about to try the heating.
Wilo pumps have been the weak link for me, they seem to start rattling after 3 or four years same as in our previous Grant oil combi. The new one had £800 spent on it last year after the water pressure wss turned up to 6 bar and the heat exchanger went alobg with other bits.
Convenience comes at a price I find!
Just to round the day off Tesco just wrote my car off for a rear light, hole in the bumper about 20x5mm and a fist sized shallow dent in the rear panel.
Happy days at least I can have a shower now....hopefully!

 

[Luggsey]

Is your expansion vessel big enough?

I think so, system pressure is solid as a rock normally