Why won't my GRUNDFOS UPS3 pump stop running?

[Stephen JW]

Hi everyone

Some very helpful people on this forum (hi John.g) sorted me out with some issues with a faulty installation of a Grundfos UPS3 back in Oct/Nov 2021.

My CH system has been running like a dream ever since. Until this evening.

For months we have been switching heat and/or water on/off manually as required due to energy bills. All good.

This evening we found that the heating was blazing away even though only the water was set to on on the controller.

Switched off both at controller but boiler kept burning and pump kept running.

Turned boiler setting down (from 3) until pilot went out.

Pump kept running upstairs. Left it 20 mins or so. Still on despite boiler now being fully switched off on front panel.

Turned off upstairs mains. Pump lost power and switched off.

Left for 5 minutes and switched mains power back on.

After 30 seconds pump switched back on (despite controller off) and simply will not switch off!

Any suggestions?

Boiler currently back on on front panel (set to 3). Water on/heat off on controller. Heating blazing!

 

[ShaunCorbs]

Stuck 2 port

 

[Stephen JW]

Stuck 2 port

Thanks Shaun

Totally novice here. You are referring to my Drayton MA1 right?
I get that if this is stuck that the water and heating would come on together regardless of whether controller is set to one or the other - but would that cause the Grunfos pump to keep running with both water & heat set to off?
Is it possible to reset the 2 port or are we talking about replacement?

Many thanks again!

 

[ShaunCorbs]

Yes need to find with a multi meter where the live is coming from either 3 port or timer