Ideal Boiler not firing up.

Much more likely to be the motorised valve if it’s stuck closed! The boiler won’t fire until the valve opens and trips the internal micro-switch in the motorised valve so if it won’t open, a) the boiler won’t fire and b) the boiler can’t heat the water as the valve is shut.

Tim

I should have added that I’d try removing the motor head and try freeing off the valve spindle with some penetrating oil and a pair of pliers. You may well end up replacing the valve anyway but you’ve nothing to lose.

Tim

If the valve is stuck, then that would seem to be the culprit. Depending on the actual wiring layout, the call for heat signal often needs to pass though microswitches built into the mechanics of the valve before it can get to the boiler.

The way to troubleshoot is to follow the signalling through from the source. So first job is identify what kind of "plan" your systems uses:

Once you know the wiring layout, you can troubleshoot with a multimeter by following the call for heat through from the programmer. Checking that it toggles as the programmer switches between HW on and off. Then check the cylinder stat, check that passes through the call for heat when you ramp its temp up and down. The possibly the valve - its microswitch may need to operate to complete the circuit.

Tim thanks. You are spot on. The valve spindle was binding, so some oil and some hundreds of turns has made it more free. The hot water now comes on so many thanks. It does drip a small bit of water which i now catch in a rag tied to the valve. I suppose that means i should think about a replacement do you think as its about twelve years old or just learn to live with a small drip ?

Replace it - it should not drip at all. If it is letting water out, it will also let air in, and that will accelerate corrosion in the rest of the CH system.

I note you have been able to move the valve but, for future reference:

Every valve I’ve encountered can be moved by hand. There is usually a lever. You tend to need to push it / wiggle it to disengage it then you can move the valve by hand, even if stuck generally. It should still operate the uSwitches.

It automatically goes back into engaged - at least the ones I’ve seen.

That said, probably best replace it.

At lesast half the time the problem is, especially if as the original post seems to imply you CANNOT manually move the valve,("this is a Danfos HPA2 whose lever is stuck in the closed position and *cannot* be moved to the open position whether the programmer is switched to calling for hot water or not"). that the valve has seized shut from scale or whatever. The trick is to electrically switch off everything heating wise and remove the motorized head. This normally keys onto a D shaft. If that is stuck use more force to free it up, because replacing it means a drain down of the whole primary circuit, or at least quite a lot of it.

If the valve moves easily, the motorized unit is f***ed and needs replacing. Sometimes a bad connection renders them inoperable but repairable., Other times the motor is plain f***ed and you need a new actuator.

Only if the shaft to the water valve is terminally seized or the glands are leaking do you need a whole new valve. Often you can free it up by wiggling back and forth and get another few years out of it.

A whole replacement valve is around £50 last time I bought one, and worth buying the lot, but only using the motor part if that's all that's wrong as draining and bleeding a CH primary is a pain in the arse and takes a lot of time.

Change it for a Honeywell equivalent model