Help testing Satchwell thermostat

[johnbey]

Is there anyone out there who could help solving a problem with my central heating system ?

The system consists of a boiler which produces hot water and warm air. The hot water is working fine but no air (warm or otherwise) is coming out of the vents and it seems that the fan is not working.

The Satchwell 2251 room thermostat is a possible cause and I am wondering if there is a simple wiring test which will show whether it is at fault.

I attach a photo of the thermostat wiring.

Any help appreciated.

 

[stem]

If those wires are in terminals 1 & 3, I'm pretty sure they are, but check first by consulting the diagram that is printed on the terminal cover you have removed. If that is the case, and you can do it safely, then you can simply join the two wires together. If the heating comes on then, the thermostat is faulty, if it doesn't you are barking up the wrong tree.

If it does work, don't leave it like that as there will not be any thermostatic control of your heating and it will just get hotter and hotter,

 

[johnbey]

Ok thanks stem, will give it a go

 

[danechip]

Any luck ?

 

[johnbey]

Will try it tomorrow. I would prefer to shut off the electricity before changing the wiring and would rather do that in daylight. Thanks for the diagram.

 

[stem]

Yes indeed, you must isolate it first there's 230v in there.

 

[johnbey]

Wired the red and blue cables together as advised. Still nothing from the fan. So I assume this puts the thermostat in the clear.

Anyone know of any other simple tests I can try to identify the fault ? If not I will call in an expert.

 

[danechip]

EDIT: You did put the power back on to test after connecting those contacts? You do have the heating on at the boiler over-riding any timer?

Do you have a multimeter? If so, WITH THE POWER OFF, Test continuity between them 2 terminals. When you hear the click turning it up and you hear a beep, beep stops turning it off to rule out bad wiring from that point. Is really isn't going to be a therostat issue now. No electronics involved, just a bi-metal strip that makes contact. other that dirty contacts which this test will rule out.

Your next step is testing the voltage coming back to inside your boiler. At this point you have really done all you can as opening your boiler is a 'GasSafe' issue so I am not allowed to advise any further on here.

 

[johnbey]

Yes and yes. No, don't have a multi-meter but I could go out and buy one. But the test involved wiring both cables to the same terminal so do I need to check continuity between them ?

When I turn the dial I hear a click at roughly the current temperature so can I assume there is nothing wrong with the strip ?

 

[danechip]

No, not for testing the wiring but the multi-meter for testing the thermostat as the click does not prove that there is a good electrical connection inside. Could be corrosion or damage though wear or arcing.

By connecting the wires together, you have basically ruled out the thermostat though.

Time for a GasSafe pro.

 

[johnbey]

Ok thanks. Will call a professional in now.

 

[danechip]

My gut guess is a dodgy contactor/relay on the control board since I guess the fan would have failed when you were last using it. They don't really go into repairing at component level but merely swap out the whole board. I have repaired a few of these boards in the past for a cheaper fix.

Please let us know how you got on.

 

[johnbey]

Ok thanks, will do

 

[johnbey]

Ok, problem fixed now by engineer. It seems I was barking up the wrong tree. I didn't realise there were two separate pilot lights, one each for hot water and warm air. The warm air one had gone out. So a simple fix in the end. But thanks stem and danechip for your contributions.

 

[danechip]

LMAO. The instructions were inside the flap. I never thought to question you on pilot lights. It is usually the Mrs job with a bit of twisted up envelope. Hope it wasn't too much.

Thanks for replying and all the best.

(Your first thanks on here) !!!!