Help needed please with CH problem

[daveym]

Hi to all. I have an Ideal classic nf40 boiler which I believe is a fully pumped system. The problem is when we switch on the programmer and request the CH nothing happens, this started about 6 months ago but at first it would eventually fire up but this past week it hasn't. After a lot of investigating I decided to buy a new room thermostat which made no difference. After more checks I thought I had narrowed it down to the diverter valve which was an acl 3 port mid position valve. I replaced this with a sunvic sdm1901 and I thought this had solved the problem as it fired up everytime I tried it. However the problem now is that the room stat will not shut off/ fire up the boiler although it still clicks , I have no control over the room temp. I checked all the wiring and found that the cylinder stat demand and satisfy wires seemed to be the wrong way round so after swapping them found that the CH works fine but the hot water has stopped working and the diverter valve isn't in the position it should be (mid) for CH/HW. I apologize for blabbing on but it's baffling me and thought it best to give as much detail as poss. I would be very grateful if anyone could suggest what the problem could be many thanks Daveym

 

[cider]

sounds like you fixed one problem but in doing so created another. the wire you swaped over on cylinder stat was doing its job before the original problem came along so i would say you have got cross wires when you changed 3 port or fiddled with room stat

 

[daveym]

Thanks for the reply cider. You're probably right. The problem I've had is that all the wiring diagrams are for programmers which can let you use the CH independently but with mine it doesn't have that option. Is there a way of testing that the cylinder stat is working correctly, just so I can count that out ? many thanks Daveym

 

[londonboy123]

sounds like you haven't wires up your components properley!!!!

 

[cider]

when i arrive on a job where the wiring may have been 'altered' i trace things back to sus out what does what and if suspect a faulty stat or valve head, have the luzury of spares on board van to swap parts to check if working correctly.
Your best option i think is to get hold of a wiring diagram for a fully pumped system(should be easy if you google it). Even though all manufactures have different components they all do the same job and can be connected together. Its just being able to understand the basics.
I would go back to your wiring of new valve and make sure thats ok and then check cylinder stat wiring.
Its easy to wire a heating system to make it get hot but wiring it correctly is another matter. Good luck!

 

[daveym]

Many thanks cider, will do and will let you know the outcome

 

[D_Hailsham]

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[daveym]

Just an update to let you know that all seems to be working fine now and all that I can think is I cleaned the contacts on the programmer but many thanks for all your help Daveym