thermostat, programmer or PCB problem???

[Mr_B]

Hi there, I was hoping that someone could point me in the right direction of where to start troubleshooting. I have a Potterton Suprima 40 and at the moment the hot water works a treat but if I switch the central heating on the boiler doesn't want to fire up. There are no noises and its like the boiler hasn't recieved the command to start.
I have reset the system, blown out any dust from the room thermostat, flicked the CH switch a few more times but nothing. As I say the HW works a treat.

Any advice to get me going would be appriciated.
Thanks in Advance,

Paul.

 

[MANDATE]

Hi Paul,
I think you could check the programmer fairly easy.My understanding is that a 'live'wire feeds both switches and then a switched live leaves each switch and goes to a 9 or 10 terminal junction box where all the connections are made to 'stats' 'motorised valve' 'boiler' 'pump' etc .
With everything off there should be no live terminals in the junc box
Now if you test again with the CH switch on and you find a live terminal then it will prove the switch is functioning
With all electric off you can test the roomstat with a continuity tester to see if it makes and breaks a circuit.
With electric on you can confirm the wire going to the stat is 'live'
This is on the assumption you have the testers and know how to use them.
You won't be able to test the pcb but there has been problems with potterton pcb on the suprima.
I'm assuming you have a motorised valve and you could do with checking that it moves when CH is selected because I think the valve motor also acts as a switch to switch the boiler on(not sure on this point)

 

[corgiman]

Hi there, I was hoping that someone could point me in the right direction of where to start troubleshooting. I have a Potterton Suprima 40 and at the moment the hot water works a treat but if I switch the central heating on the boiler doesn't want to fire up. There are no noises and its like the boiler hasn't recieved the command to start.
I have reset the system, blown out any dust from the room thermostat, flicked the CH switch a few more times but nothing. As I say the HW works a treat.

Any advice to get me going would be appriciated.
Thanks in Advance,

Paul.

No need to check either the pcb, programmer or themrostat as the problem is going to be within the diverter valve

The reason for this is that you have hw working, the diverter valve does NOT need to power on and as soon as cylinder stat demands switch live will go to boiler/pump

Dont bother with checking owt at the boiler as if there was anything wrong there then the hw would not work either but do as mandate says turn on ch at prog whack up room stat and put you finger on the slide bar on the valve head, if it dont move its not working.


The chances are you need a syncron motor for it. pretty easy job to do.

 

[Mr_B]

Thanks for your replys.

Last night I checked out the system and hopefully it is the honeywell motoraised 2port valve. I shall be removing the head this evening to investigate further.
Upon looking last night, it seems I have to remove the outer casing to look inside it and maybe find the screws inside to remove it from the valve. Is this correct?
I'm guessing its an old model as there is no slide bar on it.

Thanks again.

 

[Mr_B]

Thanks for your help guys.

I have replaced the motor and the central heating is now working. Popped down to wickes and picked one up for £16.99
MANDATE im guessing the motor does act as a switch as well.

Once again, thanks.

 

[corgiman]

Thanks for your help guys.

I have replaced the motor and the central heating is now working. Popped down to wickes and picked one up for £16.99
MANDATE im guessing the motor does act as a switch as well.

Once again, thanks.

i love it when a plan comes together

no the motor does not act as the switch but powers the arm to the micro switch as well as opening the valve.

glad to have helped