hot water but no Central Heating

[Wngstr]

I have a normal boiler (non-combi) that is 2 years old in a fully pumped open vented system, with a programmer and a thermostat in the hall. The pump is 1 year old.

I switched off the heating for a week to go on holiday and since switching it back on I have had difficulty getting the heating to come on. The hot water is fine (comes on regularly) and the boiler fires up for that, but the heating has only come on once or twice in the last few weeks. The pump is very hot and I can hear it fizzing/gurgling but no central heating.

The system has been flushed recently and I recently rebalanced the radiators as the living room radiator (the one furthest from the pump) was only luke warm with the one nearest was scorching.

Any ideas?

[Peter Stockdale]

Possibly the motorized valve, I had a similar problem -it was not switching correctly. BG fitted a new core without the need for removal - all has been well since. Pete

[Set Square]

If it's a fully pumped system, it will almost certainly have either 2 motorised zone valves - one for CH and one for HW - (S-Plan) or a single

3-port mid-position valve (Y-Plan) See for more details.

If HW is ok, the pump must be working - to some extent, at any rate. The likely culprit is the CH zone valve or mid-position valve (depending on which you've got). It *just* could be the room stat, or a wiring fault - but these are less likely.

I presume it *has* worked since you flushed and balanced it? If not, you could have a massive air lock somewhere.