Potterton Suprima 50 not working

there ok, but have been back to a few..........that is 5102160........

the new ones have been redesigned as some components on the old 5102160 board are no longer availible, so they took the oppertunity to redesign

I know this is an old post that I'm bumping here but my boiler is doing my nut in, I may have to call a plumber....
potterton suprima 50.
baisically my problem is this...the synchronous motor, only recieves power to switch the valve from its rest position (hot water) to the central heating position, after the request for heating is met the power is stopped and two springs return the valve to its rest position(hot water) does this sound right so far?
if so the problem i have is that the motor only recieves power when the valve is in a midway position (approx) after it has depressed a microswitch (?)at first i thought it was a mechanical problem so i replaced the motor for an identical 6w honeywell one £11.
but no change,I then thought it may be that the valve was sticking at the rest point but after removing the springs I realised that the pump was not recieving any power at the restpoint,I have left the springs off so I can make my heating work so my wife and 8wk old daughter are happy but I would prefer it if it were automatic any one have any suggestions??? please!

It sounds like the system is wired incorrectly. The motor isn't resting as such when it's in the middle, it's electrically stalled with DC. Go look at Honeywell Sundial Y plan here http://content.honeywell.com/uk/homes/Catalogue/Sundial Plans/3.4 Y Plan.pdf

Check your connections to the "water off" terminals of the programmer and thermostat.

The rest position is the HW position and the valve does not play an active role in this position, other than it relies on the spring to return it to this position. Electric goes through the cylinder stat direct to the boiler/pump.
The next position (mid position) introduces the CH via the room stat. this powers the motor and turns it. A microswitch stops the motor at the correct position and changes the power to a reduced level, sufficient to arrest the motor and prevent the spring from returning it.But as soon as either HW or CH is satisfied and the relative power source replaced the motor either is allowed to go back to the resting position (power removed and spring returns valve) or full power applied to motor which then continues to the CH only position. The power holds it in this positon until there is a requirement for heat on the HW. On arriving at this position there is a second micro switch which now supplies the boiler/pump as the original source via the cylinder stat has been cut off.
I dealt with a similar problem recently and found the motor moved the actuator to the correct positons, but when in CH only there was no voltage on the 'orange' wire indicating the 2nd microswitch was faulty.
It is not so simple to repair or find replacement micro switche so you may have to replace the complete actuater head (£40)

thanks both of you,
the wiring plan from honeywell was very useful, cheers Chris.

Mandate your description sounds spot on thanks for taking the time to answer, I shall dig out my multimeter and check the switches...so you think that it maybe the first miro switch which reduces the voltage to hold the valve against the spring may be ........
no the problem must be before that,there is no voltage initially so it may be the voltage from the room temp sensor which isnt getting to the motor? problem is sometimes the damn thing actually does what it is supposed to do,I hate humanising objects but sometimes it behaves like it has its own agenda...

It doesn't reduce the voltage as such but puts a diode in series. That makes a DC of sorts - yes your meter will read lower. It's an AC motor which stalls so you can't move it when it has DC applied.


There was a really good description of it on here once - I'll see if I can find it.

Think white heat and grey water. Except the water one is negative logic. White goes hi for CH and grey goes hi for NOT HW.

Maplins, hi de hi

Hi bjorn! The switched live from the room stat goes to the white wire of the valve and it is linked to both microswitches. one route through sw 1 leads to the motor at full voltage, the other route is through sw 2 and the diode/resistor to the motor.this giving the reduced power when the full voltage is removed therefore holding the valve
It would seem your problem is related to one of the micro switches which one depends on exactly what is or is not happening.

My girlfriend's Suprima 40 failed completely following a period when the showers in her home were constantly running hot then cold every few seconds.

To cut a long story short, we had the newer, improved PCB installed and it cured the problem. The faulty PCB was scorched and the new one seems to include a heatshield to protect it.

The moral of the story is simply that if your showers are behaving the same way, then you ought to think about attending to the PCB before it gives up completely - we had no hot water or central heating for 5 days during the recent snowy spell!!

If anyone can think of how a dodgy conventional boiler can make a shower go hot and cold every few seconds I'd love to hear it!!
Darkstar I'm afraid your shower problem will be unaffected by changing the boiler.

I was going to replace the complete pcb. I see one for sale on E-Bay for £60. Is this good value? How much do they normally cost?

Click to expand...

5111603 Retail for 205 + vat
trade is about 140 +
I bid em up to 60 all day long but they usually go up to £80-85 sometimes more
5102160 is about £10 cheaper on retail
The big prob with ebay is:- Can you wait for the item to end then pay for it and wait for it to arrive

Look up spares2go under the community tab. he's just one I can recommend as Ive dealt with him successfully before [there are others], mention 'slug' thats me and he might be able to put one on for you on a buy it now