boiler and ch and hw not working properly

[wikey]

hi I have a bolier potterton suprima 50L and it is not working properly. not firing up reliably, and getting worse. I have checked the junction box and checked all wiring - programmer to junction box, tank stat room stat and honeywell 4073 3 position valve.

one thing that is strange is that the return from the tank stat is live when hw is calling for heat, but it goes dead when the CH is calling . if you turn tank stat down it then goes live?

i was wondering is this right or is the valve playing up? is the valve able to deliver hw on its own and ch on its own or with ch on do you always get HW on? . i am trying to figure out if all externals to boiler are ok before calling potterton out as thy want £225 to fix it but wont touch any thing external to boiler. house is rented out but currenlty empty so i can take a bit of time to sort it but hopefully not too long. if anyone is interested i can do diagrams and email offline etc.
cheers
wikey

 

[John2512_00]

when you say its not firing up reliably do you find its 1st thing in the morning its not comming on or is it any time?

When you find its not fired up, is the lights flashing ie indicationg the boiler has locked out and needing reset?

 

[wikey]

its pretty much any time. i have the instruction book and i get flashing light combinations that are not listed

i cant remember now exactly i will have to check again the next time i am there.

i have maneged to get wiring diagrams and spec on the 4073a honeywell y valve and i am going through the wiring etc on paper to see if it seems correct.

more info next week

 

[ollski]

If it used to work fine but is developing a fault slowly then it's highly unlikely to be a wiring fault. What is the problem?, no heat, no hot water or the boiler locking out?

 

[wikey]

well i checked the junction box and found two broken wires trimmed them back and put them back in. no difference!! i am trying to make sure that the wiring is correct and that the previous tenants have not fiddled as they had done with some light switches and left them hanging off the walls.

also i want to make sure all externals to boiler are ok before calling out potterton to look at boiler. my suspicion now is pointing at the valve and once i am happy the wiring makes sense i will then start on the valve and check all its functions and signals ( voltages i suppose i mean) and see if i can eliminate it or find a fault in it.

occasionally the boiler will fire up for a while or even quite a while but it is totally unpredictable as to what makes it decide to fire.