UFH + heat pump - is it connected correctly?

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lsnk12

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Hi, we had UFH installed dowstairs in our house recently, and I'm not 100% sure that it's connected correctly. I'd be grateful if someone could have a look at the diagrams and tell me if what the plumber did makes sense. The house is heated with an A2W Samsung/Joule heatpump. The buffer cylinders (1) are located upstairs. Originally we had rads in the whole house, upstairs and downstairs. When we installed the UFH downstairs, all the downstairs rads were removed and capped off, except for a towel warmer in downstairs toilet. Here's how the system looked before:
before.jpg

And here is how it looks now:
after.png

What I'm concerned about specifically:

1) The plumber didn't install an UFH circulation pump (17), even though the heat pump manual shows there should normally be one. His explanation was that heat pumps operate at lower temperatures (max. 45C) so there's no need for a separate pump and valve at the manifold. Is that 100% correct?
2) There's no automatic bypass valve on the UFH flow (26). Is that correct? What happens if for some reason all actuators are closed but the zone valve for zone 1 is open and the heating circulating pump (16) turns on?

3) The downstairs rads were removed and capped off, but the old flow and return pipes are still connected to the rest of the system, looks like the plumber teed off the flow to the UFH from the Zone 1 flow, instead of completely disconnecting flow to the downstairs rads and redirecting it to the new UFH flow. Why would you do it this way?

4) We left one radiator downstairs, a towel warmer in a toilet. The plumber branched off the flow to that radiator from the UFH flow, before the manifold, and connected the return from that radiator after the return from the manifold. Is that not going to mess up the balance on that whole downstairs circuit? Won't all the pressure just go into the towel warmer, bypassing the UFH pipework and leaving it with very low flow?


Excuse me if anything isn't clear, it's the first time I'm dealing with any plumbing work :)
 
lsnk12 said:
Won't all the pressure just go into the towel warmer, bypassing the UFH pipework and leaving it with very low flow?
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Doesn't the towel warmer have a lockshield valve to control flow?
 
it does. Assuming it's balanced correctly there should be no issues with the flow in UFH then?
 
If there is no TRV on the towel rad then ultimately that will act as a bypass, not exactly up to current spec but will work. The amount of flow and heat it will use will be relatively small beer too especially if it's flow has been set properly. That and the UFH should have been set up with it's flow meters to ensure flow rate is OK.
Talking about bypasses though, is circuit 1's rads all TRV's and if so then should there be an autobypass designed in on that side too?
The requirement for another UFH pump would usually be driven by the size of the circuit/loops(s) and overall system requirements and whether the main pump can satisfy everything but not ideal IMO. No blending valve is a bit rough too as that means the UFH flow and floor temp can't really be managed separately but given the ASHP does run @ a low temp then only by running the system would dictate whether that would be an issue or not. Is it a slab/screed UFH?

Ultimately though, is that plan design what was agreed and paid for? If so then everything on that plan should be in the system, if it's not then the cost should have been lower and you should know that's the case
 
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I think it looks like crap design work to me

Heat pumps should not be zoned like this and should be as open loop as possible, UFH and rads should of been designed to all run at the same flow temperature

I would never use actuators on the manifold with a heat pump

What exactly is your problem though? is the heat pump working correctly? I would get someone in who knows about low temperature heating systems, the designer of this system looks like a boiler installer that's trying their hand at heat pumps. The way yours is designed with all the zone valves and actuators is likely to lead to a lot of cycling and ineffciciencies.
 
Madrab said:
If there is no TRV on the towel rad then ultimately that will act as a bypass, not exactly up to current spec but will work. The amount of flow and heat it will use will be relatively small beer too especially if it's flow has been set properly. That and the UFH should have been set up with it's flow meters to ensure flow rate is OK.
Talking about bypasses though, is circuit 1's rads all TRV's and if so then should there be an autobypass designed in on that side too?
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They've actually fitted a TRV on the towel rail, that will need to go. On circuit 1 there's 2 towel rails without TRVs and a small rad in landing with no TRV either, so I think that should be fine.
Is it a slab/screed UFH?
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It is. The quote for commissioning the UFH didn't go into details like blending valves, extra pumps, etc. I naively trusted that they'd do a proper job because I'm totally new to this...

I would never use actuators on the manifold with a heat pump
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Interesting point. There's 5 loops grouped into 2 zones on the UFH at the moment - 1 zone includes kitchen and dining area at the back of the house, and gets a lot of solar gain because it's facing south. The other zone covers hallway and living room at the front of the house, and would normally be colder than the other zone. My guess would be that it's more efficient to control them separately, but then I have zero knowledge about this stuff.

What exactly is your problem though? is the heat pump working correctly?
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Well the heat pump is working, but I have doubts whether the setup is 100% safe and as efficient as possible.

Thanks for all the responses!
 
Correct me if I'm wrong but that system is a pre-plumbed Joule buffer cylinder, it all comes pre built with the pump, zone valve etc and that's part of a design package that Joule supply? Was the installer recommended?

As far as zoning is concerned, if you have a number of distinct areas that are independently thermostatically controlled, then I wouldn't see any issue with zoning as part of any low temp design unless everything is open plan, especially if it's built in as part of a supplied design package. If there is also a distinct separation in heat requirements from any part of the system, UFH included, then separately stat controlled areas could be more efficient, how that is implemented is a different story and without a site visit it's impossible to be specific.

As far as safety is concerned then I don't think you need to worry as there are a number of safeguards built into the system but I do agree that it does look like it was added by someone who doesn't have the greatest of experience of implementing low temp UFH as part of an ASHP/Buffer system and has just 'bolted things on'. That certainly wouldn't be the most efficient as these systems do need fine tuning to set them up properly.

lsnk12 said:
The quote for commissioning the UFH didn't go into details like blending valves, extra pumps,
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Was the 'how it is now' page in your OP, what was discussed and agreed as what was to be installed? If so then I'd be looking for that design to have been implemented and if wasn't to be then discussions had and agreements made before final commissioning/sign off. Presuming this is very recent, I'd also be looking for a breakdown/confirmation on what was supplied and costs.
 
Madrab said:
Correct me if I'm wrong but that system is a pre-plumbed Joule buffer cylinder, it all comes pre built with the pump, zone valve etc and that's part of a design package that Joule supply? Was the installer recommended?
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Correct, it's a pre-plumbed Joule system. However the UFH was fitted later on by a different installer than the heat pump.

The zones roughly correspond to separate rooms, it's not an open plan.

In terms of safety/efficiency the other concern I had was about flow temperatures. Since it's a hybrid system with rads and UFH, and there's no blending valve on the manifold, isn't there a risk that the water may get too hot for the UFH and damage tiles or engineered wood?
 
A heat pump should be run on weather compensation, I would only have 1 zone for UFH and the other for radiators if I absolutely had to zone it, but it can easily be designed to all run on one flow temperature and any installer in the know would do this.

The system can then be balanced to account for solar gains. @lsnk12 what is the current COP of your heat pump? this will tell you if it's running correctly. Another issue with badly installed heat pumps is they are often oversized.
 
COP for yesterday was 3.53 (around 10-12C outside temp), the day before 3.71 (outside temp 12-13C)
 
I don't think it's a great COP considering the mild temperature, I imagine winters in Ireland will get quite cold and the COP will be ridiculous. I think a good heat pump install can acheive a cop of 4 over a whole winter.

See if there are any Heat Geek installers in your area.
 
Great source of reference information those guys but the key point is at the recap - "Beware, there are some situations where you would or should, so it's really a case-by-case basis" , not every setup is the same.

Who was it that performed the original design/planning/install of the ASHP install and CH/DHW buffer system design prior to the latest UFH install?
 
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