Some rads on permanently

[Basa1]

Had a new pump installed a few months ago to my gravity CH (it is about 20 years old and has two zone valves - was converted from solid fuel to gas about 10 years ago - but system has worked ok up to now) - I now get two upstairs and two downstairs rads permanently on (though not full heat) and lot of air in the system which seems to need bleeding regularly.

Could the pump have been fitted with the flow the wrong way or wired up wrong (the new pump was put into the original mounting - so it must be installed the same way as the original one). The zone valves appear to be working ok so it almost appears that hot water is getting back into the system via the return (from the hw tank?). Any ideas?

Help!!!

 

[kevplumb]

there is an arrow on the pump body indicating the direction of flow

might be a good place to start

 

[Basa1]

Hi,

sorry but I can't see an arrow on the pump apart from the anti-clockwise one on the central spindle (its a Grundfos pump) there might be an arrow out of sight though). I remember when the plumber fitted it he remarked that it was unusual to have it flowing in this direction - I think he said it's on the return - though I can't exactly remember. It wouldn't surprise me if the original plumbers who installed this did it in an odd way - I gather they left their torch on in the loft all weekend and burn't the roof down when istalling the plumbing!! - so I don't have a lot of faith in their work. Is it possible to wire one of these up wrong? By the way the pump is on continuously ie doesn't switch of with the stats or timer.

Thanks for your reply.

 

[kevplumb]

then it is wired up wrong
the pump should be under control of both stat and timer

 

[Basa1]

Thanks Kev,

Do you reckon this is causing all these problems? I'll have a word with the guys that fitted it - it looks like there is a sort of junction box behind the pump where umpteen wires are going in - is this some kind of control box and could this be faulty?

Regards Basa

 

[kevplumb]

dunno about faulty sounds as if the pump is wired to a permenant live

 

[gazthepottertonengineer]

are you sure pumps on all the time ??? as it could well be the non return valve on the heating got stuck as the system is a gravity one which is quite a common fault

 

[Basa1]

Yes,

I can feel it vibrating even with stats off and timer off - there are two zone valves - upstairs and downstairs - two rads upstairs and two downstairs are both warm all the time - though when the upstairs is switched on the two downstairs rads are less warm - and visa versa. When the zone valves are off the pipes seem cool and it would be a bit of a co-incidence if both failed at the same time - this appears to have been happening since the pump was replaced a few months ago - though I can't understand why the plumber who fitted it would wire it up differently - mind you he was quite young. I presume the live from the pump must some how connect to the wiring from either the clocks (there are two) or the stats.

Thanks for taking the trouble to reply.

Regards B.

 

[gazthepottertonengineer]

could be faulty heating 2 port as this sends power to pump so could be that auxilary switch inside it is stuck in on position ?? definately not pump

 

[Basa1]

Sorry,

excuse my total ignorance, but where would this switch be? There is what appears to be a juction box mounted on the wall behind the pump where all the wires come out of (it's about 3" x 5") - is this where the switch is? I presume this would need a replacement unit. The only other controls are the two clocks. Certainly, the reason I had the pump replaced was that the fuse kept blowing - this might be the consequence.

Again thanks for you patience.

 

[gazthepottertonengineer]

auxilary switch is inside the two port valve and if faulty would mean replacement of 2 port head

 

[Basa1]

Thanks for this,

I have two zone valves, any way of telling which could be the faulty one?

Regards B