pump runs for ages

[purpledog]

Hi,

I have a gravity system and there's a pump there so I guess that it used to pump the hot water in the radiator.
Sometimes, when the heating is off, this pump keeps on pumping (and making noise) for hours. Do you know what that could be the case?

If the heating (and the hot-water) is off, surely the pump should not work... ??


This is what is on the pump:
MYSON unit fove
240v 1-50hz 0-49A 115W
code 890 U5C252


There's also another device around:
MYSON AERJEC II 0290


Also, even if that's probably irrelevant, there's two valves attached to the hot water tank:

1) SUNVIC SZ1301

2) DANTOSS RANDHILL LTD
"auto/man" switch
MK429ER TYPE HPA2

 

[corgiman]

what boiler do you have?

 

[purpledog]

It says "ideal w2000"

 

[gas4you]

It sounds as though the microswitch in the Danfoss HPA2 valve head has broken and stuck on.

Fit a new head. You can do this yourself if you disconnect the electrics and replace one wire at a time so as not to wire the new one up incorrectly.

 

[purpledog]

Do you reckon I should replace it with the same exact one or maybe a different brand.

According to an online vendor, the other alternatives are:
Landis & Gyr SK2
Pegler Sunvic SZ1301, SZ2301
Potterton PMV2 Actuator

 

[twgas]

same one, if you use a different one you'll probably have to change the complete valve.

 

[purpledog]

done, seems to work. Need to see it in the long run but the pump stopped running without a reason (and does run when the heating is on).

So... THANK YOU!
And I mean it!