suprima not responding on ch only hw

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hi guys, its my first time on this forum aswell as my first time with a boiler problem!! My potterton suprima is not firing up (not even the fan or any signs of life) however the hw powers up perfectly. It is obvious (is it?) to suggest that all the mechanical parts are ok ie pump , fan etc as it is fine on the hw side of things. I read the forums and the pcb seemed to play up so i soldered the dry joints but no change (i may have missed some bits). Iam no expert but it al points to the problem being the pcb but if the hw works fine could this still be the case? (could it be that the part of the ciruit board controls the ch seperatly and that bit happens to be faulty?
 
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my very first thought would be to change the sychron motor on the 3 port valve or on the heating zone valve. If you have a 3 port valve there should be a little lever on the side....push it across a little bit more and your heating will fire up. If it does get a new motor to go in the valve head.
 
cheers for the advice but where is this valve , or what does it look like ?
im not experienced .
 
probably in your airing cupboard. You will either have 2 valves with big square heads on them and an electric cable and each valve having 2 pipes connected to it, or you will have just one with 3 pipes connected.
Either this
pwhv0013s.jpg


or this
pwhv0012s.jpg


The heads will look different for different brands, but the body will look the same
 
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oh dear, have a broke it? i pulled the only lever i could find towards myself (it was a bit stiff, felt like i was pulling agains the motor) and it hasnt made a difference. The water still works but no responce from the heating. Shame that cos i thought we was onto a winner .
 
Even on the hook it won't get the boiler on. You can get that going for now by putting the hot water on. Id you've opened the way to the rads they'll get warm at the same time.
Turn HW cyl stat right up and Boiler stat down - so HW never satisfied, thenrads will be hot. Til you fix it I mean
 
hi again, just read all your messages thanks for being suportive in my hour of coldness. I sort of understand now!! So i will hook the lever open so the rads will warm. Whats that about the stat up and the stat down and where are they? Ive got a temp dial on my boiler is that one of them.

So basically is it a knackered pcb thats not telling the 3 way valve thingy to work or is it in need of a new motor? Or worse still is the pcb at fault aswell as the 3 way valve?cos at the end of the day i still have the problem of the boiler not responding when i press for the ch

Sorry if i sound confusing jim
 
If as you say the HW works fine then you can rule out pcb in my opinion. I would concentrate on the motorised valve and veryify that it moves to mid positon and on to the final position if CH only is selected. If the head of the valve is removable off the valve spindle it is easier to see the actuator turn. When the actuator turns it activates a couple of micro switches, one of which supplies power to the boiler through the valves orange wire. You can look in the 10 terminal junction box and identify this wire and test it. Your problem suggests either the motor is not turning the valve or if it is turning the valve the micro switch is not supplying power to fire up the boiler. What happens when you select both HW and CH? Do you get any CH for a short period.
:rolleyes: :rolleyes: :rolleyes:
 
cheers mandate that explains a few things, i agree that the pcb sounds ok if it fires the hw up ok.
So you say it could be the valve. Some plumber said i could fit a new motor to it for about a tenner. Would this not cure the microswitch problem though? How do i test if i need a full new valve or just the motor? I have pulled the lever back then down into a groove which has obviously opened it up. Which is the mid position and how do i test this.
By the way if i press the hw and ch together on the timer the boiler fires up (probably on the hw) if i quickly switch the hw off the boiler stays fired up for about 2 seconds on the ch alone (maybe until it realises).But generally the ch doesnt activate at all. Thanks jim
 
Fitting a new motor would not cure a micro switch problem. You need two things to happen. A. The motor needs to move the valve to the final positon and the micro switches need to be activated to get power to the boiler. I only have experience of a potterton valve where the valve head was removed off the spindle and I could watch the motor drive the actuator forward or return by the return spring as different selections were made. ( tends to be a bit of a delay in starting the movement). Next tested the voltage on the orange wire when in CH mode only. Nothing! A replacement actuator head was fitted, problem solved. You can also test and lubricate the spindle while you have the head off.
New valve complete about £65. New actuator head was £38. New motor about £15.
:rolleyes: :rolleyes: :rolleyes:
 
Another point worth a mention. If you select both HW and CH it does not mean the valve will stay in the mid positon. As soon as one part of the sytem is satisfied the valve will move to the non satisfied part. In winter I think the HW will be satisfied sooner than CH because the heat loss on CH will be greater ( HW not in continual use) so the valve spends more time in the CH positon even though both HW and CH selected. I found if hot water was run off at the tap the boiler started and CH was ok, that was until HW satisfied. This was because the power needed to flash up the boiler, although not available from the valve, was supplied from the cylinder stat.
:rolleyes: :rolleyes: :rolleyes:
 
thats a great help mandate cheers ,

i will check to see if anything is working in the valve and let you know what i find!!!

thinking about it though, if it was just a motor problem then the ch would have fired up when i pulled the lever back manually so perhaps it is the actuator head ?

cheers
 
hi guys, hopefully it is just a valve motor that need so i have sourced one on ebay and it is a honeywell synchrone motor for a 2 and 3 port valve.
Just wondered will this be ok for the valve i have.Im not sure what mine is but it was installed from new with my potterton suprima 30
thanks dudes.....jim
 

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