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We have started putting the heating back on occasionally for the first time since last winter.
The boiler keeps firing up for a minute or so every 30 mins or so even after everything has switched off ?!?
This means that the bathroom radiator (only one not on a TRV) is getting very very hot, and we are using oil when we shouldnt be.
Is this likely to be a boiler issue, or some of the vales in the system? There is one mechanical valve that does open each time the switch for the boiler is triggered. I am not sure if this is fully closing properly when the boiler switches off because manually pushing it closed did appear to solve the issue, however this now appears not to be working.
The boiler is under warranty with WB so I could get them out, but I have heard they are very expensive if it is not a boiler issue, and the issue is some where else in the system.
Pic below is the valve that I think is faulty
Any ideas welcomed Ta
There is one mechanical valve that does open each time the switch for the boiler is triggered. I am not sure if this is fully closing properly when the boiler switches off because manually pushing it closed did appear to solve the issue, however this now appears not to be working.
Could be, the motorised valve also closes a circuit when it opens which normally fires up the boiler, so if it gets stuck open it will keep the boiler + pump powered.
The sequence is normally Timer / thermostat -> open motorised valve -> powers boiler + pump via a secondary circuit
You could try working it a few times open / closed to see if you can loosen it up.
It it won't close it would suggest that the mechanical valve is sticking. The units come in two parts, there is the wet valve and then a bolt on motor unit which sits on top. You can change the motor without needing to drain the system, two bolts and 4 wires. IIRC the motor opens the valve against a spring and it relies on the spring to close the valve. If the valve won't close, you probably need a new wet half, which is DIY able (I've done loads over the years), but involves draining the system.
Our HW one dies every 5 years or so (or the motor does). The CH heating one is 30 years old!
Are all the other rads getting hot, and is the house getting up to your target temperature before the boiler switches off?
Is there a thermostat, or just the thermostatic valves?
Do you have only a few rads open, with the rest shut down at the valve?
Does sound like a valve woe. The plastic part of head should left off by pressing in a black tab. Once the head is off See if you can move the exposed end of the paddle. If you cant then its seized up. Sometimes moving it gently from side to side will give you a bit more time but it may need replacing. Btw there is not much movement on that part.
Most likely a dodgy micro switch in the motorised head if the valve body moves freely.