Weird flow rate issue

[Adam2]

So, setup is:

ASHP

Buffer

4 x manifolds each with local pump on the flow after the mixing valve

Return pipes collectively go through a pump 

Fairly new system - Wunda/Wilo/Grundfos (return pump)

 

ASHP working fine, hot water on DHW and buffer is hot

3 manifolds OK and heating floors (well 2 I can test and are OK 1 I cannot test easily at the mo)

 

1 manifold (this is on a floor below the plant room with Buffer etc) has a simple setup with flow guages on the return part and manual valves on the flow (plumber & electrician figured as 1 zone why bother installing the Salus auto actuators that I have, will deal with that later). The flow guages all read "0" no matter what I do, they are pretty much fully open and the manual valves on the flow I tried either fully opening /closing and no difference. The pump is running (Wilo para) and set to UFH and low speed but I tried experimenting and no joy.

I checked for air in manifold with the manual bleed and a small amount came out. What may be unusual is that the flow part would do a good pee but the return was a dribbler - implying a lot less pressure?

Pump does sound like has air so I've done a few of the forced air removal things by pressing the green button in for 3 secs.

If on the mixing valve I close it up -so min temp, I then get some flow guage action - but as soon as I open it up to let hot water in, the guages go back to zero

 

Looks like an issue possibly with the mixing valve not bringing in hot supply or the zone valve looking like it is open but not really being open

 

Can't see what else to check - would appreciate suggestions. The pressure looks like it's 1.5 bar (in plant room so slightly more presumably 3m down)

 

Cheers for ideas - will post a pic of manifold. 

[Adam2]

Oh and room thermostat calling for heat

[Temp]

40 minutes ago, Adam2 said:

 

1 manifold (this is on a floor below the plant room with Buffer etc) has a simple setup with flow guages on the return part and manual valves on the flow

 

Check that. The picture here says "6. Manual Return Valves"

 

https://www.wundagroup.com/wp-content/uploads/2019/10/M07-generic-Wunda-premium-Manifold-25-4-2018.pdf

 

 

[Adam2]

Thanks @Temp my mistake in the typing, seems I cannot edit the earlier post.

 

Correction - flow valves are of course on the flow side and the manual valves are on the return as per the link above

Edited September 29, 2022 by Adam2
Add more info

[Temp]

Other thing to check would be the pump direction. Usually an arrow on it somewhere.

[Temp]

 

56 minutes ago, Adam2 said:

If on the mixing valve I close it up -so min temp, I then get some flow guage action - but as soon as I open it up to let hot water in, the guages go back to zero

 

 

Also double check the flow and return pipes from the buffer to the manifold aren't swapped over. On a shower mixer this can cause the cartridge to runaway to the end stop, eg full hot or full cold.

 

Edit: Not sure this would cause the symptoms you have though.

Edited September 29, 2022 by Temp

[Adam2]

2 minutes ago, Temp said:

Also double check the flow and return pipes from the buffer to the manifold aren't swapped over

That may be a challenge as it's all of course in walls/floors now. If only my pipe conducted electricity 🙂 

[JohnMo]

Mine did similar, it was air in the system.  Needs a good blow through with the hose pipe.  Once air purged, worked as it should.

[Adam2]

11 hours ago, JohnMo said:

Mine did similar, it was air in the system.  Needs a good blow through with the hose pipe.  Once air purged, worked as it should.

Yes thanks seems most likely so on that today before itnge

[Adam2]

Yes lots of air got in the pipes - this floor is fed from the floor above but the pipes go up into the ceiling along 20m then down about 6m so a bit of a journey. All sorted

[JohnMo]

Normally the simple fixes do it.