@jamespa

I can't honestly remember what the situation was with the valve but I can double check with the old engineer. He knew UFH but not Heat Pumps. The latest guys know Heat Pumps (apparently!) but not UFH so it makes life complicated.

There are currently thermostats in every room that would turn them on and off. We've still got these set to a high temp though so everything is running all the time.

And apologies, I'm guessing it is l/min not hour. I'm an idiot.

At present we're getting rooms heated between 19 and 22 which is comfortable for us so I'm guessing the flow rate isn't causing an issue with heating but it worries me that its less than the minimum for this pump.

The only MelCloud reports are what I've already posted. I'm hoping the Melpump website is going to be more useful now I'm logged into it. Sadly a lot of the useful reports on MELCloud are lost after 24 hours so Melpump doesn't have access to the historical data. 

@davidnolan22 There's seven...

You’ve got 16 loops

Do you remember if the heat pump installers changed the UFH flows from the oil system it was installed for.

@davidnolan22 

Looking at a photo of the manifolds from when they were installed I'd say they look pretty much the same. The guys that fitted the tank and pump said they didn't have much experience with UFH. 😬

Posted by: @sandman1600

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There are currently thermostats in every room that would turn them on and off. We've still got these set to a high temp though so everything is running all the time.

Good  I guess these operate the actuators on each loop but maybe one on each manifold operates the zone valve?  If tyhere is nothing else to set high and everything is getting warm it must be OK!

Posted by: @sandman1600

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At present we're getting rooms heated between 19 and 22 which is comfortable for us so I'm guessing the flow rate isn't causing an issue with heating but it worries me that its less than the minimum for this pump.

This is a bit odd but as its manually set I am guessing the installers set it to get a reasonable deltaT, which would equate to setting it low if (as we suspect) your heat loss is much less than 14kW.  My guess is they looked at the deltaT, decided it should be a few degree not less than a degree, and slowed the water pump down.  I dont think it matters much, you may get a marginally better COPOif you turn it up (simple thermodynamics says you will get a better COP but the 'engineering' effects are unclear), but then again you may not.  Its only going to be a few % anyway,.

Posted by: @sandman1600

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The only MelCloud reports are what I've already posted.

Strange, the manual suggests otherwise.  Maybe they have withdrawn functionality or maybe the extra reports are only available on windows devices, not a phone?  Unfortunately you can never tell!

@sandman1600 

it sounds like they have just tired  to replicate your oil boiler with a heat pump. I’d be a little concerned that the heat pump installers didn’t want to know more about the emitters. 

someone is going to have to take some responsibility for your whole system. Who that is might be the tricky bit.  Might need to be you. 

I think you emitter power at mean water temp 50 is 9.5kw, it’s normal that you have emitters 20% bigger than your heat loss, so that’s great. But more typically the emitters would also be a bit bigger than the heat pump at the designed mean water temp. Your design was for mean water temp 42 I think. 

james, would you say might be worth increasing flows through manifolds, or you think this again might narrow DTs too much from already tight 3

Posted by: @davidnolan22

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james, would you say might be worth increasing flows through manifolds, or you think this again might narrow DTs too much from already tight 3

Honestly no idea. 

The simple thermodynamics say that lower DT is always better.  I have not heard a coherent explanation why we design for DT 5 not the minimum DT reasonably achievable (which may be, and is in this case, lower). 

In the absence of a coherent explanation I am unclear whether anything, other than power consumed by the water pump, argues against the simple thermodynamics.  Some, including some who should know, assert that it does, but without coherent explanation (and so I give only limited credibility to their assertions!).

The folks on openenergymonitor are unequivocal that the thermodynamics plus water pump electric consumption are the only material considerations, and they are generally pretty scientific.

In summary don't know.  I may try it on my Vaillant some day!

@jamespa 

My only thinking is that I'm sure he will have a header.  The only thing we actually know is the primary circuit flow rate the primary circuit temps and DT.  We actually don't know what's going on the secondary side

If the heat pump team did not touch the UFH other than pipe to it, then I can't believe the oil system was set to run a DT of 3 through the manifolds.

Its really hard to know the secondary flow rates and I'm not sure how accurate the manifold knobs are to tell you.  I'd want to know the DT over the each manifold. If the primary DT is 3, but the manifolds are at 7 or 8, then that would tell me the combined secondary flows are lower than 17/18 and there is room to increase the flow through the secondary side and increase the emitter output. 

Posted by: @davidnolan22

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My only thinking is that I'm sure he will have a header.  

I have been trying to work that out from the photos.  Still not sure, but like you I suspect that there may be one and it might account for a 10%+ efficiency penalty

This is a bit of the photos (near the manifold) Im curious about  -whats the uninsulated pipe doing and is that a second pump.  I cant actually see anything that looks like a LLH, but that doesnt mean there isnt one!

@jamespa 

and, just circulate around the primary circuit if flows to UFh strangled. 

uninsulated pipe will be the cold feed for the blending valve

Posted by: @gary

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uninsulated pipe will be the cold feed for the blending valve

I thought that but it seems to go to the UFH not the DHW and it should still be warm assuming its from the return, so surely one would insulate it?