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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Plumbing Questions >> Replacement of heating zone-valve https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1293525920 Message started by Norman Grant on Dec 28^th, 2010, 8:45am

Title: Replacement of heating zone-valve
Post by Norman Grant on Dec 28^th, 2010, 8:45am

Hi, I need to replace a British Gas zone-valve-BGM VSP-2 on my hot-water circuit. Is it possible to avoid having to drain-down the system by putting bungs into my header tank as for replacing a radiator valve? Also, when it says that this kind of zone valve can be easily replaced by a Drayton(Invensys)ZA5 ,is the wiring easy to reconnect to the junction-box.Will the colour code for the wires be exactly the same ? Many Thanks.
Norman Grant

Title: Re: Replacement of heating zone-valve
Post by Lectrician on Dec 28^th, 2010, 10:28am

Without a freezing kit you would need to drain.

I am not sure how you managed to swap rad valves by simply bunging the header tank TBH?

I am not familiar with the BG make, but believe they simply re-brand items as their own, so if it looks the same, chances are it is.

Title: Re: Replacement of heating zone-valve
Post by big_all on Dec 28^th, 2010, 11:29am

Lectrician wrote on Dec 28^th, 2010, 10:28am:

I am not sure how you managed to swap rad valves by simply bunging the header tank TBH?

surface tension slows the water down to a dribble as the air has to replace the water
you will get water from a little bit to a lot the flow can even stop
then again being rough with the pipes can break the vacuum

the idea is you get a controlled flow a fraction off what it would be

Title: Re: Replacement of heating zone-valve
Post by Norman Grant on Dec 28^th, 2010, 3:03pm

Hi,Thanks for your reply.I had watched a BRITISH gAS plumber replace my central heating zone valve without draining down and wondered if I could do thesamefor the hot water valve.He got a few pansof water but not much. Can I ask about the zone valve which I think is faulty.At present with the cold weather the central heating is on a lot and I noticed that the hot water seemed to be on a lot as well.Idiscovered that even if the hot-water was off at the controler,the hot tank remained very hot and the pipe from the zone valve to the cylinder was very hot.I took the actuator off and the spindle seemed free to move by about 45 degrees.I could see the actuator turning as I switched on and off the hot water at the conroller. I now had manual control of the zone valve but even if the spindle seemed to be definitely in the closed position, the hot water was clearly getting into the cylinder whenever the central heating is on.Is it possible for the spinle to seem to be at closed but the mechanism inside to be faulty and to be letting hot water through? This is why I want to replace the zone valve.Does this make sense? In the meantime I am running up a huge gas bill!
Thanks again for any advice.
Norman grant

Title: Re: Replacement of heating zone-valve
Post by thescruff on Dec 28^th, 2010, 8:11pm

You sure there's not a frost stat bring the boiler on.

If there is fit a pipe stat in line with the frost stat so it turns it off again when it records heat.

Title: Re: Replacement of heating zone-valve
Post by CWatters on Jan 2^nd, 2011, 10:57pm

wrote on Dec 28^th, 2010, 3:03pm:

the pipe from the zone valve to the cylinder was very hot..

How close is it? It's surprising how far heat from a cylinder can travel along a pipe.

Perhaps best test the valve by turning off the hot water (or disabling it) and then running the heating?