Potterton Suprima 30- 80 circulation pump running constantly

[eliseman]

Hi Chaps

This seems like the place to be for any DIY problems. Hope you can help.

I have the above boiler in a house which is now 5 years old.

I have noticed that the circulation pump wont shut down even when there are no demands on the heating or the hot water. When I say continuosly I mean day and niight.

The only way the punp can be stopped is to shut down the boiler altogether.

I have also noticed a bit of Kettling.

Any ideas please + if not a DIY job then can anyone in the Sittingbourne area recommend a good heating engineer please.

Thank you

 

[ChrisR]

First thing to do is check the wiring. The pump should get power from the boiler, but might not .

 

[eliseman]

Thanks for that Chris.

I belive that the pump receives it's power from the boiler.

I have nosed around the neighbours system which is identical. His pump only seems to run when there is a demand.

Cheers mate

 

[geoff@cetltd]

yes. it SHOULD get it's power from the PCB

If so, the pump relay could have welded itself open

The pump should run on demand and for 20 mins after it ceases

 

[Gasguru]

The kettling is normally due to scale in the heat exchanger but sometimes the burner pressure is set too high - the gas valve adjustment is VERY sensitive on the Suprima. I've seen Suprima's burning 50% over the rated input.

 

[eliseman]

Thank you all for your replies. It is really apprecaited.

 

[ChrisR]

If you open the door on the right you'll see that the panel behind it is held by just one screw. If you remove that, and pull the door forwards sliding the metalwork off, you'll see the connection block.
Underneath it, the leftmost 3 terminals have a label saying pump, where you should have wires connected.
If all ok there , new pcb needed


CHeck that the system isn't "pumping over" (ie water coming out of the vent pipe over the header tank in the loft). If not, then , short of a full chemical/power flush, you could add some "Boiler descaler" (there's a type you don't have to flush out), and then maybe "Boiler silencer".

And "Inhibitor" would be a Good Thing.

 

[eliseman]

ChrisR

I have taken the cover off. There are three wires going to the connector block that you describe. The block is labelled "pump".

The three wires go into the top of the block but there are none connected to the bottom of the block, ie all three terminate in the block.

What should be happening here ?

Cheers m8

 

[iliko]

Hi all,

I am facing the same issue as eliseman.
The work done so far is as follows:

1) Replaced the 3-way valve with the head, (along with new wiring, for the pump too).
2) Replaced the hot water tank temperature sensor
3) Replaced Honeywell Home T4360A Frost Thermostat 40C to 80C T4360A1009
4) Replaced PCB
5) Replaced heat sensor (thermistor)

Before the thermistor, the boiler turned off when the required temperature reached, but after the thermistor changed, neither the pump nor the boiler turned off.

What else it could be?

 

[Stuckinarut]

You should have created your own thread really, this one is nearly 20 years old! I would be looking at external controls and eliminate by process.

 

[iliko]

You should have created your own thread really, this one is nearly 20 years old! I would be looking at external controls and eliminate by process.

I agree, but I thought this was the best thread to keep the content.
Can you elaborate on what parts you mean by external controls?

 

[Stuckinarut]

Can you elaborate on what parts you mean by external controls?

Yes, the motorised valve(s), thermostat, programmer. Something is sending a voltage to the pump by the sounds of it

 

[iliko]

Yes, the motorised valve(s), thermostat, programmer. Something is sending a voltage to the pump by the sounds of it

I see what you mean. The motorised valve can not send power to itself it gets it from the boiler which in turn may get it from the thermostat/ programmer which is Hive and was rewired. So when CH or HW is on I can see the green light indicating the "command" was sent to the boiler. IN this case, both lights are off but the boiler is still working andthe pumping is spinning.

 

[Stuckinarut]

The motorised valve can not send power to itself it gets it from the boiler

Very unusual, it’s usually programmer - room or cylinder stat - motorised valve - boiler and pump

 

[iliko]

When I changed the thermistor there was a white paste looking like a conductive paste. Since I changed it the boiler barely turns off after scheduled heating time over + runover time.
Previous to the change the boiler was stopping but the pump was still running, but now both are working. Oddly enough when outside temperature goes over +10C both are working fine.
Is it possible my Hive Thermostat is broken?