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Central Heating Pump Runs Continuously


 
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JB1

from United Kingdom

Joined: 23 Jan 2010
Posts: 4
Location: Northamptonshire,
United Kingdom

PostPosted: Sat Jan 23, 2010 3:44 pm Reply with quote

Hi, Any ideas please. My central heating has been running fine up to about a week and half ago when the cold the cold weather hit. Now the CH pump will not shut down it runs 24x7 whether the heating is on or off. I've tried changing the frost stat ( The boiler is in the garage) the pump overrun stat on the boiler and the overheat stat on the boiler and the thing keeps on running. Any ideas?
The pump is a grundfoss and the boiler is a Potterton Netaheat Profile 80e.

The CH and HW are working fine and the boiler works fine when the timer kicks in.

Help!!!
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tomy

from United Kingdom

Joined: 19 Aug 2005
Posts: 375
Location: Cheshire,
United Kingdom
Thanked: 14 times

PostPosted: Sat Jan 23, 2010 4:53 pm Reply with quote

Two port or three port valve is faulty
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JB1

from United Kingdom

Joined: 23 Jan 2010
Posts: 4
Location: Northamptonshire,
United Kingdom

PostPosted: Sat Jan 23, 2010 6:14 pm Reply with quote

Yep I thought that might be the case. But when I turn off the CH and the HW independantly. They both activate.
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Corgigrouch

from United Kingdom

Joined: 13 Dec 2007
Posts: 3170
Location: United Kingdom
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PostPosted: Sat Jan 23, 2010 6:26 pm Reply with quote

Which boiler is it?
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JB1

from United Kingdom

Joined: 23 Jan 2010
Posts: 4
Location: Northamptonshire,
United Kingdom

PostPosted: Sat Jan 23, 2010 6:52 pm Reply with quote

the boiler is a Potterton Netaheat Profile 80e.
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gas112

from Unknown or unspecified country

Joined: 27 Oct 2009
Posts: 8161
Location: Unknown or unspecified country
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PostPosted: Sat Jan 23, 2010 8:38 pm Reply with quote

Does the boiler boiler fire up as well every so often if so its microswitch in motorised valve.
If it doesnt it will be the pump over run stat in boiler at fault
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steve32

from United Kingdom

Joined: 23 Nov 2008
Posts: 525
Location: Essex,
United Kingdom
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PostPosted: Sat Jan 23, 2010 8:40 pm Reply with quote

micro switch in the mv is stuck on
you may be able to free it or replace head
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JB1

from United Kingdom

Joined: 23 Jan 2010
Posts: 4
Location: Northamptonshire,
United Kingdom

PostPosted: Sun Jan 24, 2010 11:21 am Reply with quote

Ok so which one or both MV's do I change. The system has 2 x 2port MV's fitted. I've had a play this morning and they seem to be working ok but the HW MV was sticky. Pump is still running with the system off. Also the boiler does cut in intermittantly when the HW and CH is turned off on the timer.
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tomy

from United Kingdom

Joined: 19 Aug 2005
Posts: 375
Location: Cheshire,
United Kingdom
Thanked: 14 times

PostPosted: Sun Jan 24, 2010 11:50 am Reply with quote

check the wiring to see which one or maybe both will feed the boiler then disconect and test with a multimeter to see which valve is supplying 240v to the boiler when it shouldnt be.
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