Worcester System boiler with unvented cylinder. Seems to function fine when the heating is on, but as soon as you turn the heating off the cylinder is no longer heated. The Danfoss HPA2 motorised valve to the cylinder coil seems to work/move across to open the valve. Could it be the the microswitch inside has failed which is no longer triggering the boiler to fire?
Quite possible . When you say it seems to work ,what do you mean ,it works manually ,or it does actually move electrically ?
It will move across/rotate when the thermostat on the tank is adjusted up/down. i.e. it's opening the flow of water, but isn't getting the boiler to fire.
Microswitch or wiring issue ,probably the former. Check the wiring centre for loose connections ,if all good,fit a new actuator
Perfect, thank you - that's very reassuring. Is there a wiring diagram somewhere for them so I can check the voltages on the terminals in the wiring centre?
I tested the voltages on the orange wire today. When closed, 70v. When open and calling for heat, 240v. Seems the micro switch is working as it should….
The oranges should both be in the same terminal. I’m guessing the orange wire that belongs to the heating valve is in the correct terminal.
Actually if you move any orange wire that would leave a black wire itself. Looks like the 2 oranges and 2 blacks should be together
I found this article in the manual for the terminal box. The wire colours don't seem to correspond with the colours as wired up in my box. As you say, both oranges seem connected together in the manual too. Rotated photo of my terminal box and rotated it to show the same orientation as the manual.
Just bought the house so it's all new to me. Haven't moved in yet but I found I had to use the electric immersion heater to warm the water instead of the gas boiler.
As Mike said both orange switched lives should be in the same terminal,move the red link wire as he advised.
There will obviously be a black wire connected with the oranges that probably serves no purpose. As you have a system boiler the oranges would usually only tie in with 1 other wire. It won’t cause any issues though as your not really changing that anyway.