UFH Manifold puzzle

[Sumo]

Hello, I am a looking for advice for my DIY brain before I contact a plumber.

Last winter I took over the responsability for a Zubadan 8kw ASHP connected to seven double rads and a three loop UFH manifold. Having noticed the ASHP short cycle, every 5-10 minutes with a 3 minute shutdown I decided to investigate as a novice. I wont go through all the symptoms I spent months fathoming over in this post, I will start one in the plumbing section, but here I will cut to what I think is the issue.

The Manifold I think is installed wrong????

Pictures below. I bought an infra red heat sensor to figure this out.

So, I think the flow and return copper pipe is the wrong way around! and the pump is not helping.

Onto the numbers, the lower copper to the trv reads in centigrade at 48, the upper pipe from the manual valve reads 36! So to me, the flow is coming in the bottom  and not through the top flow valves, as it should? To add to this, the flow temps in the lower plastic pipes is 25/26 and in the upper plastic pipes it reads 36.

I want to swap the flow and return and reposition the pump into the flow pipe, I will block heat the concrete slab on economy seven, with no mixer valve needed and the zones all open, so as one circuit on a timer and wall stats with set back.

Any thoughts for my sanity are welcome.

 

[JohnMo]

Hot normally goes to the flow meters. DeltaT looks large for a heat pump, normally around 5 to 6.

 

Are you running rads and UFH at the same temperature?

[Sumo]

Thanks for the reply Johnmo. I always run the rads seperately, with both on at the same time nothing gets hot. But yes I run both at 47 to try to block heat the slab on eco7.

The ASHP is set to 47, it was set to 51 but I noticed it having to work very hard over 47 to get to 51 and then it would overshoot. With just the UFH on the rads get a flow of upto 25 degrees through them, with the highest temps coming on the rads at the far end of the loop, so backwards.

The best delta I have had at the ASHP is 13, mostly 15, despite trying every pump combination to get better, the flow meters all reads 3 on the manifold. Two Grundfoss pumps, one either side of ashp.

I am sure the manifold is the problem, as you and all the internet says flow in the top. I just want lots of opinons saying, yes the manifold must plumbed wrong. Thanks.

Edited September 25, 2023 by Sumo

[ProDave]

I think it is piped correctly, though intuitively it does not seem right at first glance.

 

There are several types of UFH manifold and in particular the way the blending valve works.  I had not see one like yours before, so I did a little searching and I found this:

 

http://www.gasapplianceguide.co.uk/UNIPIPE Manifold.htm

 

That appears to show it piped as yours is.

[Sumo]

Hello Dave, thanks for the reply. My manifold is an uponor 782??08.

Yes, I have come across that image before. I found it confused? They point to the flow and return to/from the boiler in the same orientation as mine but then when you look at there flow and return to/from the ufh they are marked as the reverse directions to there input flows, so I think they have misslabellled the diagram? I considered this for a while and assumed a clever network of pipes hidden in the manifold, but no, they are just open voids.

[Sumo]

I do agree Dave, that the mixing pump can be on the right side, however as we do not need a mixing system to protect the floor I would like to use it as purely a circulating pump on the inlet.