Cold tap is warm when recirculating pump is on

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Naughty- don't think placcie is allowed for recirculating dhw. Doesn't solve your problem of course....
 
There's a couple of oddities on the cold piping on your schematic.
First one is the link that apparently bypasses the group valve to tie both controlled and uncontrolled cold to the expansion vessel.
Second one is that little green zigzag that appears to link cold with UFH return (if that's actually a filling loop with at least 1 check valve then fine but there's no good reason for it to be on that side of the group valve).
Yes - I've had a look at the "group valve" specification and it's odd how it's been configured. Regarding the link that bypasses the group valve, the installation engineer fitted that at a later date to the original installation (about a week later) and also added the pipework for the tundish (an afterthought?).

The group valve is fitted with the expansion takeoff point hard against the wall, so were they forced to use another method of adding the expansion capability? It doesn't seem to be possible to contact the original installation company so I'm thinking I probably need to contact a heating engineer at this point to review the installation and fix the issues. It's difficult enough to get used to the ASHP and all of its idiosyncrasies without having to fault-find an issue with the basic pipework.
 
I believe it's JG.

This may be a bigger problem.

Most companies including JG that produce polybutylene pipe don't recommend using on a secondary return system.


You may get future problems.
 
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Naughty- don't think placcie is allowed for recirculating dhw. Doesn't solve your problem of course....
Sorry if I've misled you - the pipework in the plant room is all in copper. At the point where it leaves the plant room, it's then in plastic. The attached picture shows the installation before the engineer came back to complete the work.
 

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So the dhw supply and return pipes are both plastic from the plantroom to their destinations? As above, this could give long-term problems, none of the plastic pipe suppliers afaik have type approval for placcie pipe in your type of setup. Again, doesn't solve your original problem but does throw some shade at your plumber or builder.
 
So the dhw supply and return pipes are both plastic from the plantroom to their destinations? As above, this could give long-term problems, none of the plastic pipe suppliers afaik have type approval for placcie pipe in your type of setup. Again, doesn't solve your original problem but does throw some shade at your plumber or builder.


Butline allow use of their stuff under conditions
 
Sorry if I've misled you - the pipework in the plant room is all in copper. At the point where it leaves the plant room, it's then in plastic. The attached picture shows the installation before the engineer came back to complete the work.


He looks to have done a great job but he's made a big mistake.

I'd be trying to get him back if I were you.
 
So the dhw supply and return pipes are both plastic from the plantroom to their destinations? As above, this could give long-term problems, none of the plastic pipe suppliers afaik have type approval for placcie pipe in your type of setup. Again, doesn't solve your original problem but does throw some shade at your plumber or builder.
To be fair, I've just looked this morning as far as I could into the ceiling space and it looks like it's in copper. I remember seeing lots of plastic pipe before the plasterboard was fitted but didn't think to take any photos at the time. I can say that all of the pipework to the UFH manifold is in 28mm copper so that's one good thing!

On another note, now that I've switched off the recirculation pump, it looks like there's a bit of a leak from it - I never noticed before. I've had no luck contacting the installation company but I'll drive to the place tomorrow if they won't pick up the phone.
 
He looks to have done a great job but he's made a big mistake.

I'd be trying to get him back if I were you.
The plant room work was implemented by the ASHP installer (all in press fit as you see) and was then reviewed by a Vaillant engineer - everything after the gate valves to the DHW, cold supply and UFH pipes was installed by the builder (the builder won't be coming back).
 
The plant room work was implemented by the ASHP installer (all in press fit as you see) and was then reviewed by a Vaillant engineer - everything after the gate valves to the DHW, cold supply and UFH pipes was installed by the builder (the builder won't be coming back).

You are where you are so my best advice is:

Have the pump on a timer and have it come on as least amount of time possible.
1 - 2 mins just before shower/bath times.

Just switching the pump off is not an option as then you enter bacteria problems such as Legionnaires.

So have the pump kick in at least once a day.

Good luck

Bod
 
If the builder won't come back then don't make him aware of his mistake as one day he will píss off the wrong person and won't get away with his shabby work.
 
You are where you are so my best advice is:

Have the pump on a timer and have it come on as least amount of time possible.
1 - 2 mins just before shower/bath times.

Just switching the pump off is not an option as then you enter bacteria problems such as Legionnaires.

So have the pump kick in at least once a day.

Good luck

Bod If the builder won't come back then don't make him aware of his mistake as one day he will píss off the wrong person and won't get away with his shabby work.
Thanks - I'll do as you say regarding the pump - my DHW temperature is set to 52 degC (ASHP flow is at 45 degC) so I do rely on refreshing the water in the cylinder regularly. As for the original builder, he's lost out on a *lot* more work - that's the way I'm looking at it :)
 
Thanks - I'll do as you say regarding the pump - my DHW temperature is set to 52 degC (ASHP flow is at 45 degC) so I do rely on refreshing the water in the cylinder regularly. As for the original builder, he's lost out on a *lot* more work - that's the way I'm looking at it :)

I'd put the temperature on 60 degrees.
 
 

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