We’ve got a Vaillant ecotec boiler, the hot water works absolutely fine but the central heating isn’t working. I don’t think it’s come on once since the gas safety check a few weeks ago. In terms of stuff I’ve checked:
Pressure is normal,
All of the radiators are bled,
The remote thermostat tells the boiler to put the heating on,
The thermostat receiver gets the signal and the right lights flash to show it’s on,
the boiler clicks on and makes the usual humming sounds,
the c/h pipes in and out of the boiler are hot,
…but all of the radiators are completely cold. 😕

I’m hoping there’s just some valve/switch that the boiler bloke turned off for the safety check/service and he then forgot to open it back up when he finished. Anyone got any ideas?

If there’s nothing obvious (and a quick Google didn’t give me much hope) then it’ll have to wait until Tuesday when we can contact the letting agents.

Is there a pump external to the boiler that circulates the hot water around the central heating circuit? If so, it may be worth checking if that is working.

What model Ecotec? Does the number start with a 4 or 6 or 8 or 9?

Do you have a motorised 3 port valve aware? These can stick / fail.

If the pipes are both hot check if he opened the bypass valve. That’s the valve close to the boiler which stops the pump exploding if all the radiator valves are closed. Which is something else to check.

Because the boiler is getting the signal from the room thermostat, then the stat/programmer/valves(s) are working correctly.
It goes like this – programmer says on – room thermostat says on – valve opens and closes/opens its microswitches, which tell the boiler to turn on.

The wiring for the pump live, and the boiler live are in the same terminal in the connection box – it should be number 10. Check the pump is getting mains voltage when the stat is calling for heat. If so, feel if the pump is moving – they only slightly vibrate when running.

It is most likely to be a failed/failing pump, or, a blockage in the pipework, stopping the pump working.
First check is power at the pump.
If no power when the stat is calling for heat, then it’ll be a wiring fault. If there is powere, then most likely a failed pump.

Do you have a vertical pipe near the pump with a small thumbscrew on top? We have one for releasing airlocks around the pump, same symtons you’re experiencing when it gets an airlock.

Or, as said before, stuck 3 way valve, it should have a manual override on the side.

Thanks guys!

It’s an 831 (r1). AFAIK there’s no external pump (it’s a small, single floor flat so I don’t think there’s any need for one).

Radiator valves are open, the bypass valves are both closed.

Checking voltages is a step too far unfortunately (partly because I don’t have a multimeter) so I’ll leave that to a professional.

Am I right in thinking that to get to the pump I’d have to remove the front cover? If so, again, I’ll leave that to the professionals.