Sulking boiler

An update. Having turned the power on and off to the boiler several times it seems to working now. Something’s not right, but I don’t know what…

Tim

I did find a fault on a boiler once where the gas valve closed itself when it got warm... However that seems far less likely on what I presume is a premix modulating valve with stepper motor control rather than the old fixed rate solenoid controlled valves.

Strange stuff can happen when the PSU section of the PSU starts to give up. The main PSU reservoir cap turned out to be the culprit on my EcoTec.

Pretty sure this boiler pre-dates any form of gas modulation. The valve has two solenoids in series, each controlled by two wires. I’m guessing a modulating valve is a bit fancier.

I’ll have a closer look next time I’m in the loft.

Tim

Isn't the green LED to show that the water preheat is active? On my ecomax no LEDs are lit when it's off, and an amber when it's firing. I think.

Ah ok older than I was expecting. Has it got an always on pilot light?

Having said that, thinking back the boiler I was diagnosing did not shut off the pump - just the flame - and I was able to measure the mains "call for heat" to the valve remained on all the time even though the flame went out.

Yup modulating valves normally have a stepper motor to allow it to be driven to varying degrees of "open" (on modern boilers, you can often hear the slight click as it steps while hunting around for the required output level)

It might be a far simpler PC on that class of boiler.

This is what the one in my ecotec looks like:

The Baxi I have modulates with an analogue voltage, presumably a solenoid valve working against a spring that opens in a gradual and controlled way.

It has a separate on/off solenoid valve so could be similar to function as yours.

Sounds like you might need to look into the anti-cycling function of the PCB. A job for Geoff Drage (raden) if he's not managed to retire yet. Google CET or CET Ltd in Watford

What about the controller that sits on yer wall. Brian

Have you checked there isn’t air trapped in the heat exchanger?

If the pipe work around the boiler is such that the boiler is a ‘high point’ air ( actually gas produced by water attacking the pipes etc) can collect in the boiler. There should be a bleed point to let it escape. The same can happen if you’ve drained the system. When you refill, the heat exchanger partially fills and the system gets confused. On ours, it does flag a fault.

It can also happen when you first turn the CH on in the autumn, just as the rads need bleeding, even if you have inhibitor in the system, you still get a bit of air / gas collecting, even if the HW system has been running.

Last time I spoke to him (end of last year) he was talking about retirement, but had not yet quite got around to it :-)