Central Heating not working

[Booldawg]

There was me posting a question about my in-laws boiler getting condemned last week and now my system isnt working :-(

We're getting hot water but no central heating. What can it be? Hopefully something simple like the thermostat I hope.

We have BG coming out this afternoon as we have breakdown cover but I'd like an idea as to what it could be to prepare me for the worst!

[buildersmate]

Could be the thermostat - but less likely. Have you tried turning it up / down and listening for the 'click' as the mechanical ones switch on/off?
More likely to be the diverter valve that switches the water supply between the CH and the DHW (or both) is not working - it could be stuck in the 'DHW' position.
I can't really guess what sort of system you have.

[Booldawg]

Hi BM. Yes the thermostat is clicking as I turn it up and down. The system is an old Baxi boiler probably dating from the mid 80s (at a guess)

[buildersmate]

Many moons ago, early DHW systems worked off a gravity-feed method. There was no pump and the water that heats the DHW just circulated around of its own accord.
When early CH appeared, the pump that was necessary to get water into the rads just did that - it was not used to heat the DHW cyclinder. If you have one that old, then the pump is probably knackered.
When the drive to improve efficiency in the system started to occur in the 80s, a diverter valve was inserted in the bolier water flow and both the DHW and the CH gets heated using the pump. If you've got one like that, it is probably the diverter valve that is knackered. It can't be the pump because you've still got DHW.

[Booldawg]

Thanks BM. At least I can drop a few hints to the BG engineer which may give the illusion I know a little about it! Else I fear he'll try and pull the wool over my eyes. Not sure if spare parts are readily available and doubt BG will bust a gut to try and source anything. Ho hum the joys of being a house owner!

[terence7556]

can we have an update after the engineers visit

[terence7556]

ps how did your in laws resolve their problem?

[Booldawg]

Yup, the engineers been out. As BM had suggested it was the valve that needed replacing. I'm over the moon as he had one in the van so it was all done in one visit.

The valve was in the airing cupboard and from what I saw attaches to a motor for a pump. Luckily we have the BG Homecare insurance so it didnt cost anything.