Unvented stange behaviour (split thread)

[mkjonhston]

Hi,

I don't want to hijack the thread - however, this is the only about POTTERTON PROMAX 15 SL so people might be in the "know" here.
I have a santon premier plus PP210B unvented indirect cylinder up at 2nd floor in conjunction with a POTTERTON PROMAX 15 SL placed down in the kitchen, and experience the following problems:

1) During summer time when we only need shower, everything works perfectly.
2) Once we turn the heating on during winter time, we get the following:
a) The water pump (SurePump SP65/130) that sits just close to the Santon cylinder won't stop spinning once the boiler downstairs stops burning gas.
b) Sometimes, the Potterson shows the lower-right LED (visible after detaching the magnetic lower cap) becomes blinking red, and the boiler won't start burning.
c) A shutdown from the switch found close to the Potterson control panel for a couple of hours, puts the system back in function. The system will “recover” or start working normally sometimes if the reset (from the lower-right side of the boiler) button is pressed. When the pump does not stop working, I noticed that @ the reset button, there are visible the normal green LED but also a blinking red LED light … reseting it or power cycling the boiler will get rid of the red blinking light.

Does anyone have a guess of what might cause the above symptoms?

Thanks and much appreciated for any suggestions.

 

[Agile]

You should really have started your own thread.

You may have an interaction between the flow temperature set on the boiler and the stat on the cylinder.

Do you know what flow temp the boiler stat is set for?

Water should be set for 60 C and no higher. The boiler temperature while heating water should be 10 C higher so 70 C.

I am wondering if the cylinder is set too high or the boiler too low!

On an unvented like that adjusting the temperature is hardly a DIY activity and often the stat is not calibrated with degrees.

Tony

 

[picasso]

Had any work done to your system and do you have a room stat?

 

[mkjonhston]

Hi,
Thanks for replies so far.
A couple of clarifications:
1) The system works flawlessly for heating up the bathroom / shower water. So, I assume there's no miss-alignment between the Promax and the cylinder here.
2) The problem starts developing only when we switch Central Heating on (for ex., we press +1HR to get 1 hour heat). Initially, the system starts heating & room radiators work just fine). However, after one, two or 3 days of normal functioninng, @ the end of the heating "window" - tipically 22.00 or 23.00, even though the Boiler stops, the Water pump that's placed near the cylinder up stairs, continues spinning all night ... failing to stop. That's when usually, the boiler start developing the "error" state - (continuous green + blinking red LED). And that's when we need to reset the Boiler (either by reset button press for 10-20 sec, or by switching of completely the boiler for a couple of hours).

The room temperature is controlled through a "room" thermostat placed downstairs close to kitchen. It's a circular rotor / analog one - and I assume that's the thermostat for the Promax SL boiler.
The cylinder settings are found in the attached picture, and seem to be normal ...

Thanks

 

[mkjonhston]

You should really have started your own thread.

You may have an interaction between the flow temperature set on the boiler and the stat on the cylinder.

Do you know what flow temp the boiler stat is set for?

Water should be set for 60 C and no higher. The boiler temperature while heating water should be 10 C higher so 70 C.

Tony

I won't try to DIY with this one ... however, I would like to understand what's happening. How can I check the boiler temperature setting?

 

[mkjonhston]

Had any work done to your system and do you have a room stat?

no, it worked just fine in the last 4 years, we started experinencing these issues intermitently last winter. However, a reset would fix it and we did not call anyone.

 

[picasso]

I would get the wiring checked out, on this boiler if you have a room stat the pump should not be wired to the boiler, it should be wired to the switched live, the pump should stop when there is no call for heat.

 

[mkjonhston]

I would get the wiring checked out, on this boiler if you have a room stat the pump should not be wired to the boiler, it should be wired to the switched live, the pump should stop when there is no call for heat.

thanks - it does stop for tap hot water and sometimes for the radiators ... problem is - it's not consistent behavior ... and I cannot explain the error (red blinking) on the boiler when it goes wrong.

one thing crossing my mind that might cause an issue - if the heating window (ending let's say at 23.00, programmable from the console) passes away and the room stat is still switched on (meaning target temperature hasn't been reached) - the boiler will typically stop. But the pump stays on as the system is "thinking" there's still more heating to be done ... since target temperature hasn't been reached ... you thing a wiring missalignment could cause this ?

 

[picasso]

Faulty zone valve would be my first guess.

 

[mkjonhston]

picasso, thanks for the fast answer.
is there any resource(s) around here in order to:
1) find location of the zone valve,
2) confirm the fault
3) establish whether this is a DIY or not

Thanks!

 

[picasso]

Confirm the fault...

after the central heating has been running turn off the water and heating at the programmer if the pump continues to run and the red (overheat) light comes on then microswitch stuck in zone valve.

find the location of the zone valve...

you "should " have two valves just after the pump but could be anywhere.

establish if this is diy or not...

its not rocket surgery but you should be fairly confident with electricity.

 

[mkjonhston]

Confirm the fault...

after the central heating has been running turn off the water and heating at the programmer if the pump continues to run and the red (overheat) light comes on then microswitch stuck in zone valve.

find the location of the zone valve...

you "should " have two valves just after the pump but could be anywhere.

establish if this is diy or not...

its not rocket surgery but you should be fairly confident with electricity.

Thanks !
I'll take it piece by piece and see how it goes.
If there's something I'm fully confident with, is wires ... a bit less with pipes though

 

[picasso]

All modern zone valves have removable heads so no need to touch pipes.

 

[mkjonhston]

Confirm the fault...

after the central heating has been running turn off the water and heating at the programmer if the pump continues to run and the red (overheat) light comes on then microswitch stuck in zone valve.

find the location of the zone valve...

you "should " have two valves just after the pump but could be anywhere.

establish if this is diy or not...

its not rocket surgery but you should be fairly confident with electricity.

Thanks !
I'll take it piece by piece and see how it goes.
If there's something I'm fully confident with, is wires ... a bit less with pipes though

Problem solved - it was indeed the heating zone valve - it's the white one in the background, not the one opened in the foreground.
The lever that actions it manually was being dragged with the motor when valve opened, and when trying to close, the lever was blocking the motor of closing the valve ... a bit of grease and everything was fixed ... picture with the culprit ...

Thanks!