Promax FSB HE - central heating not working but hot water still fine.

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EverythingsBroken

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If I turn on the hot water, the boiler starts up first time and works fine, but it is completely unresponsive to me turning on the central heating. It doesn't make any sounds, no flashing lights (just power on, and flame off like it's still on standby).

Is there anything obvious I should check? CH has been off for the past 2-3 months over summer.
 

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As the boiler fires for hot water it’s not a boiler fault, check the thermostat first and post a pic of the heating valves( near your hot water cylinder normally)
 
In the picture, that Danfoss RX1 receiver is connected to a hot water thermostat in the tank that should just control the HW temperature (that's powered on and working). I'm not aware of a CH thermostat. There aren't many valves around the hot water cylinder; there are more valves near the boiler (both pictured). I'd need to move the fridge to get a better look.
 

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Two zone valves behind the fridge ,one is for central heating . It's either failed or it's not getting an electric supply.
 
Thanks. Obviously I'll turn the power off at the breaker before I look around here but how should I go about troubleshooting this?
1. is there an easy way to tell which one is the CH and which is the HW?
2. Are there likely to be fuses in that white box or is it just to hide the cable being split? (There's a fuse at the source that must be fine if everything else is going through it)
3. Once I've determined which valve it is and that it does have power, and is still not working, is it possible to fix or does it need to be replaced?
 

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The valves you have you can just replace the actuator (head part) or probably is the synchron motor which is cheaper to replace , no need to drain anything down
 
Before doing the above, as @picasso says, check the room thermostat, which appears to be fastened to some timber in the cylinder cupboard? Or could be a wireless cylinder thermostat - check the temp setting and batteries as it's wireless. The receiver is the rx1
 
1. Follow the pipe from top of valve ,one will go to the hot water cylinder,the valve nearest the pump probably goes to cylinder, and the left valve to heating circuit.
2. The white box is the wiring centre.
3. Refer to the posts by Ianmcd and CBW above.
 
CBW said:
Before doing the above, as @picasso says, check the room thermostat, which appears to be fastened to some timber in the cylinder cupboard? Or could be a wireless cylinder thermostat - check the temp setting and batteries as it's wireless. The receiver is the rx1
Click to expand...
That thermostat is just for the hot water - it's set to 49 degrees and has a thermometer attached to the tank. I guess as the RX1 only receives 1 signal, and this is the only receiver plugged into the heating controls, that I don't have a CH thermostat. There's a really old looking one in another room, but the wire goes into the wall and I don't know where it comes out. It's a long way from the heating controls though and I don't see any other wires going into the heating controls other than the one from the RX1. I assumed it was disconnected and left over from a previous system update.
 

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It could still be connected, try turning it down and up a couple of times and see if it clicks.
 
EverythingsBroken said:
It does click, does that mean it has power? I have no idea where that wire goes
Click to expand...
Here's a diagram of everything I found. Even if that wall thermostat has power, I don't see where it would connect to any of this to control the valve.
 

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Ok start with the ch zone valve, with the controls calling for central heating see if the lever on the ch zone valve is easy to move or has a fair bit of resistance.
 
picasso said:
Ok start with the ch zone valve, with the controls calling for central heating see if the lever on the ch zone valve is easy to move or has a fair bit of resistance.
Click to expand...
Thanks for pointing me towards the lever. It's starting to look like the problem is with the control panel (as if the thermostat is set to cold or is broken).

I've moved the CH zone valve lever to manual and when the HW comes on, the radiators warm up - so I know the valve itself is not jammed.

The whole system is unresponsive to the CH being turned on - the zone valve motor doesn't turn, and the boiler doesn't turn on. I'm not sure what to do next but is it normal to have a setup like this without a CH thermostat? If I did have a CH thermostat, where would it be connected to this setup?

At least I have some CH now, but it turns off when the HW tank is at temperature, so if the house gets cold, I need to do the dishes.
 
Sounds like the valve actuator. Putting in manual means just that, it doesn’t prove any electrical microswitch failure.
 
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