Boiler not getting signal

aldub83

i have a new 2 zone heating system.new boiler and controls etc converted from oil. Worked fine for a few months and now has stopped working. Boiler won’t start up but is working and ready for signal to work as has 00 on digital display and pressure is good. Lights come on the controls but nothing seems to happen on boiler. Plumber says it electrical and Murphy’s law when the electrician came it worked but won’t work now. lights coming on on motorised valves and set right

any ideas?

youtheman

Normally the zone valve limit switches are wired in parallel such that any zone valve open causes a signal to the boiler to fire. So first check is to go to the zone valves and operate the lever to manually open them. You would have to have two faulty valves/switches for the system not to work altogether.

aldub83

Thanks for comment. I put the zone valves on manual and nothing happens.

there lighting up but boiler not kicking in.

Wearb

I don't know if manual lever activates the micro switch on all types of zone valves. 🤔

aldub83

Could a faulty thermostat cause this?

youtheman

A faulty thermostat or controller could prevent the zone valve from opening. But by opening the valve manually you are essentially 'bypassing' the controller and thermostat. The controller outputs a 220 volt signal when required, this passes through the thermostat and open/closes the zone valve. This is all it does, it is not connected to the boiler. Separately the zone limit switches are wired in parallel to the boiler such that any one zone valve open calls for the boiler to fire. So the zone limit switch is the only device that fires the boiler.

Not sure how the light is wired in the valve, but I presume it is connected to the limit switch. So if I was a betting man then I'd assume you have a wiring problem with your limit switches. Based on the fact that neither switch operates I'd be reasonably confident it is a wiring problem.

aldub83

Thanks for that. Great explanation