Hot water but no central heating

[simonbridge]

I have a Hepworth Fuelsaver 45, I posted that I was getting banging from the system on morning startup and have thus acquired a new pump, some sludge remover and some inhibitor for when all is clean, however..... I put the sludge cleaner in the F&E tank, turned on the CH to circulate and yet the rads don't get hot (all are on full temp), no noise of circulating water through them. They are fully bled.

The pump is working. I have a Honeywell 8816 2 port zone valve (for very old Baxi open fire back boiler), that appears free on the mechanical movement.

I cannot see any three port valves anywhere, does that mean diversion is done at the boiler end?

I don't know where to start now, lashings of hot water but cold CH. Any ideas guys?

 

[ArtfulBodger]

Try to work out where the problem is. You have a two port valve on a back boiler, so can we assume you have gravity feeds for your hot water? if the valve appears to be free, can you feel heat immediately before and after the valve? if so, where does it stop?

Have you tried isolating the expansion tank and partially draining the system then checking to see if the water level goes down in the F&E tank. If it does then you're laughing 'cos your cold feed isn't blocked. If it doesn't then you're still laughing as there is loads of advice here on blocked cold feeds.

If you can isolate the old pump, take it off and check just how free it is and whether it is seriously constricted by sludge. It might be that it just can't pump water even though it sounds like it can (assuming you do have gravity primaries for your hot water. If it is, put your new pump on and see if this makes a difference.

Anyway, after all that, you can't just dump the sludge remover in the F&E tank when full and expect it to circulate immediately.

 

[simonbridge]

Thanks Artful, just the right sort of advice.

I have now changed the pump, drained, refilled and bled the system. This is where it gets weird.. i contacted Hepworths who said that the only possible solution was that the 3 way valve was faulty as this is a fully pumped system. However......

There is only a two way valve, a Honeywell 8916. so I agree with you that this must be a gravity fed system, seems plausible as its an open F&E 4 floors above the boiler. Anyway, I have stuck the multimeter across the brown wire on the 2way and it reads 220V when the CH is on the controller, the port however is closed (normally closed valve). This appears to suggest that the motorised valve is buggered (do you agree????). There is hot water on one side and cold pipe on the other side (of valve). When I manually open the valve the CH starts working, yippee!

So the only question I have now before I nip off to spend £60 on a new 2 way is....
Is it the valve or the controller at fault now.

Thanks for your help, this has been fun.
Regards
Simon
PS: I answer in the computers section (IT manager of SME) so if I can ever return the favour , just ask.

 

[croydoncorgi]

If the BROWN wire on a Honeywell 2-port valve is live and the valve is still shut, chances are the synchron motor in the valve is blown. You can replace just the motor for 15 quid or so.

 

[simonbridge]

Thanks all.