Panasonic aquarea - dual zone cooling @ diff temps possible?

[SBMS]

We are in the process of installing all the pipework for a Panasonic M series ASHP - 7x fancoils upstairs and UFH downstairs.  

 

My goal - and reason for picking the Panasonic - was the ability to run dual cooling zones via the ASHP.  My plan if it gets hot was to run the fancoils at 10 degrees and the UFH at 15-16 degrees.  The installer - who has been great - has had some conflicting information from Panasonic.  Initially we were told that this was fine, and the Panasonic supports dual cooling zones, but we've been waiting for a hydraulic schematic from Panasonic.  Today we had a technical engineer from Panasonic tell us that he's not sure this is possible natively with the system, and its back to us.  We are seeking advice further from Panasonic tech installation.

 

In the meantime - has anyone managed to design and install this system to produce an FCU cooling loop at 10 degrees and UFH at a higher temp and if so how? Our installer is looking into it as well and may come back with a design, but are rightly nervous of designing their 'own' and not following a Panasonic approved schematic..

 

I know that many will say that its not necessary, run it at one temp etc. I get that, and if thats the fallback so be it.  But we've lagged all the pipework for the FCUs, installed condensates throughout and basically prepped it for low temp cooling to maximise the cooling output of the FCUs.  I really want to make that work, without having to push 16 degree water around both circuits and would be grateful if anyone has got this to work, or knows of a way.

Edited Tuesday at 19:20 by SBMS

[-rick-]

No specific knowledge here but I am curious:

1. What is your current plan?

2. They claim to support dual zone heating with different temps? I'd assume so. How are they doing that?

3. Are you referring to purely simultaneous cooling? Can it do one zone at a time at different temps?

 

I have a couple of ideas for things you could do but depends on the proposed setup.

[Nick Laslett]

Not sure how the ‘M’ is different to the ‘J’?

 

Here are the pages from the installation set-up for the ‘J’ ashp about 2 zones, different temps. 
 

https://www.panasonicproclub.com/uploads/GB/catalogues/2023/UK_INSTALLATION_MANUAL_H 2023v3.pdf

Edited Tuesday at 20:36 by Nick Laslett

[SBMS]

I wasn’t sure if the Panasonic dual zone control is built for heating - not for cooling but that seems To indicate it might. Alternatively I wondered if I had to provide dual zone cooling by hydraulic means. 
 

i am not an engineer but was thinking…

 

Heat pump produces 10deg water into buffer 

FCU takes 10 deg water direct from buffer and returns back to buffer. 
UFH branch comes off buffer with a 3 way thermostatic mixing valve with a hard min of say 16 degrees. Valve blends the 10deg water from buffer with the return from UFH circuit with output to the UFH.

UFH circuit would be separately pumped and return to buffer. 
 

i could also go for a more advanced controller at the mixing valve that could read the UFH temp and mix accordingly based on the temp -

or even integrate with a dewpoint sensor. 
 

Would something like the above work?

Edited Tuesday at 20:51 by SBMS

[-rick-]

Definitely sounds like it should be possible. They are relying on mixing valves and running the heatpump at the highest (heating) or lowest (cooling) temperature so it's not necessarily the most efficient but I wouldn't expect you to need the very low cooling temps outside of heatwaves.

 

 

[SBMS]

2 minutes ago, -rick- said:

Definitely sounds like it should be possible. They are relying on mixing valves and running the heatpump at the highest (heating) or lowest (cooling) temperature so it's not necessarily the most efficient but I wouldn't expect you to need the very low cooling temps outside of heatwaves.

 

 

This looks almost exactly like what I designed but it’s built into the heat pump!! Is that a fair summary??

[JohnMo]

Read a lot of ASHP manuals (yes sad), they all seem to work in a similar fashion. The ASHP receives a zero volt signal to run the second operating temperature, otherwise it runs at normal temperature So if your UFH is only calling for heat only it runs at one temperature, if your upstairs also calling for heat the second set point comes in, a mixer valve then mixes up/down in cooling/heating

 

Work equally well for heat and cooling.

 

You need (generally) an electronic mixer valve,  volt free thermostat in addition to what in your fan coils, maybe a buffer or ideally a volumiser to cover just the fan coils calling for heat.

 

Adds loads of additional complexity.

[-rick-]

3 minutes ago, SBMS said:

Heat pump produces 10deg water into buffer 

FCU takes 10 deg water direct from buffer and returns back to buffer. 
UFH branch comes off buffer with a 3 way thermostatic mixing valve with a hard min of say 16 degrees. Valve blends the 10deg water from buffer with the return from UFH circuit with output to the UFH.

UFH circuit would be separately pumped and return to buffer. 

 

I think the issue is with the mixing valve. A normal analog thermostatic valve can't have different set points for hot and cold. I'd guess that many digital ones also require more setup work/software support to do this. Maybe their inbuilt control of digital valves is the problem? If so, wouldn't seem hard to make sure you bought valves that could handle two set points and wire them seperately from the rest of the system. Not sure off hand why they would need to be wired into the heatpump except for monitoring reasons, they should be set and forget.

[SBMS]

5 minutes ago, -rick- said:

 

I think the issue is with the mixing valve. A normal analog thermostatic valve can't have different set points for hot and cold. I'd guess that many digital ones also require more setup work/software support to do this. Maybe their inbuilt control of digital valves is the problem? If so, wouldn't seem hard to make sure you bought valves that could handle two set points and wire them seperately from the rest of the system. Not sure off hand why they would need to be wired into the heatpump except for monitoring reasons, they should be set and forget.

Is the same issue present in the Panasonic ‘2 zone layout both mixed’ schematic? Or does it control The mixing valve using the zone water sensor? 

Edited Tuesday at 21:01 by SBMS

[Nick Laslett]

I don’t believe you need the dual temperatures. Supply water just above the dew point and I expect you will get the house cool enough with UFH and Fancoils running at those temps. 
 

Plenty of anecdotal comments here about Fancoils delivering at temps above dew point.

 

The trick is to never let the house overheat in the first place. The ASHP weather compensation will supply the cooling before the house ever gets really hot. 
 

You can use Home Assistant connected to a dew point sensor to control the Panasonic ASHP flow temp. @Dave Jones
 

Quote

As its actually nice today, tried out running the heatpump in reverse to cool the house.  To keep above dewpoint (home assistant takes care of this) set at 16C, had the slab down to 16 within 4 hours and the house is noticeably cooler when walking inside. Have 5 panasonic fancoil units in the bedrooms which will test once the painters are done.

 

[SBMS]

13 minutes ago, Nick Laslett said:

I don’t believe you need the dual temperatures. Supply water just above the dew point and I expect you will get the house cool enough with UFH and Fancoils running at those temps. 
 

Plenty of anecdotal comments here about Fancoils delivering at temps above dew point.

 

The trick is to never let the house overheat in the first place. The ASHP weather compensation will supply the cooling before the house ever gets really hot. 
 

You can use Home Assistant connected to a dew point sensor to control the Panasonic ASHP flow temp. @Dave Jones
 

 

Thanks for this but seeing as I have already installed and lagged pipes and CAN run at 10 degrees (which also dehumidifies) I’d like the option of it. Would also like FCUs sized appropriately and not oversized to cope with a reduction in output when running at 16deg. If it turns out I don’t need to I can simply set both zones to 16 degrees,

enjoy a better COP and achieve the same. Im just keen to understand if the heat pump natively supports this…

Edited Tuesday at 21:22 by SBMS

[JohnMo]

6 minutes ago, Nick Laslett said:

Fancoils delivering at temps above dew point

But they have to be sized correctly to do that.

 

7 minutes ago, Nick Laslett said:

trick is to never let the house overheat in the first place

True

7 minutes ago, Nick Laslett said:

You can use Home Assistant connected to a dew point sensor to control the Panasonic ASHP flow temp

You can, but after loosing internet (signal from source - not house internet issue) for quite a few hours the other day, I wouldn't let anything internet based anywhere near the heating system.

 

In most of the UK if you never allow house to overheat, you run at about 13 degs without any condensation issues.

[SBMS]

1 minute ago, JohnMo said:

But they have to be sized correctly to do that.

 

True

You can, but after loosing internet (signal from source - not house internet issue) for quite a few hours the other day, I wouldn't let anything internet based anywhere near the heating system.

 

In most of the UK if you never allow house to overheat, you run at about 13 degs without any condensation issues.

Thanks and understand everyone’s points. Let’s just assume I understand everyone’s points that I may not need to run it that cold and could run above dewpoint temp. Id still like to size my FCUs appropriately and can see no downside to have a system that can do 10

deg supply - even if its only on a couple days a year. 
 

From the literature it looks like the heat pump does provide this and it’s design is quite similar to my niaive design that didn’t rely on the Panasonic controller??

[Gus Potter]

4 hours ago, SBMS said:

We are in the process of installing all the pipework for a Panasonic M series ASHP - 7x fancoils upstairs and UFH downstairs.  

 

My goal - and reason for picking the Panasonic - was the ability to run dual cooling zones via the ASHP.  My plan if it gets hot was to run the fancoils at 10 degrees and the UFH at 15-16 degrees.  The installer - who has been great - has had some conflicting information from Panasonic.  Initially we were told that this was fine, and the Panasonic supports dual cooling zones, but we've been waiting for a hydraulic schematic from Panasonic.  Today we had a technical engineer from Panasonic tell us that he's not sure this is possible natively with the system, and its back to us.  We are seeking advice further from Panasonic tech installation.

 

In the meantime - has anyone managed to design and install this system to produce an FCU cooling loop at 10 degrees and UFH at a higher temp and if so how? Our installer is looking into it as well and may come back with a design, but are rightly nervous of designing their 'own' and not following a Panasonic approved schematic..

 

I know that many will say that its not necessary, run it at one temp etc. I get that, and if thats the fallback so be it.  But we've lagged all the pipework for the FCUs, installed condensates throughout and basically prepped it for low temp cooling to maximise the cooling output of the FCUs.  I really want to make that work, without having to push 16 degree water around both circuits and would be grateful if anyone has got this to work, or knows of a way.

So you posted this 3 hours ago, hopefully I caught you in time. I might not have. but hey ho.

 

Points: 

 

1/ If you are designing your heating cooling system based on what is available above the floor, ASHP then I think you are making a big mistake. STOP NOW and make sure you build in redundancy into your fixed UFH pipes that are not maintainable.

 

If you dought me go back and ask you designer if they will warranty what is going on under the floor and for how long. Ask, what if I come to sell the house, is that going to impact on the asset value. 

 

2/ If your UFH pipes don't have the flexibilty to accomodate in the future a different ASHP then you are totally locked in. You will regret it. 

 

@SBMS

In the meantime - has anyone managed to design and install this system to produce an FCU cooling loop at 10 degrees.

 

To do this you need more loops. This also does my head in. You have a sofa, say big patio doors, the sofa insulates the floor but just inside the glass doors the floor gets hot! UFH design is a craft, but most is commonscence. What is not good sense is to take software output and think the computer knows best which far too many on BH are doing ! The software is a guide and that is it!

 

Let common sense prevail. 

 

But at the big glass doors in the winter you have a thermal bridge so the floor gets cold here, drafts come down off the glass, I close up the loops here! Loop cad does not pick this up for example and many designers just bury their heads in the sand. 

 

In the summer the floor next to the glazing gets hot, so here you need to cool it most so the closer centres helps.

 

What I'm trying to say is that you do your pipes under the floor with pragmatism and benefiting from the "no shite" advice I give you. That then opens up what is going on above the floor and gives you options for a system that will work for 50 years and not pelt the asset value of your house. 

Edited Tuesday at 23:48 by Gus Potter

[SBMS]

9 hours ago, Gus Potter said:

So you posted this 3 hours ago, hopefully I caught you in time. I might not have. but hey ho.

 

Points: 

 

1/ If you are designing your heating cooling system based on what is available above the floor, ASHP then I think you are making a big mistake. STOP NOW and make sure you build in redundancy into your fixed UFH pipes that are not maintainable.

 

If you dought me go back and ask you designer if they will warranty what is going on under the floor and for how long. Ask, what if I come to sell the house, is that going to impact on the asset value. 

 

2/ If your UFH pipes don't have the flexibilty to accomodate in the future a different ASHP then you are totally locked in. You will regret it. 

 

@SBMS

In the meantime - has anyone managed to design and install this system to produce an FCU cooling loop at 10 degrees.

 

To do this you need more loops. This also does my head in. You have a sofa, say big patio doors, the sofa insulates the floor but just inside the glass doors the floor gets hot! UFH design is a craft, but most is commonscence. What is not good sense is to take software output and think the computer knows best which far too many on BH are doing ! The software is a guide and that is it!

 

Let common sense prevail. 

 

But at the big glass doors in the winter you have a thermal bridge so the floor gets cold here, drafts come down off the glass, I close up the loops here! Loop cad does not pick this up for example and many designers just bury their heads in the sand. 

 

In the summer the floor next to the glazing gets hot, so here you need to cool it most so the closer centres helps.

 

What I'm trying to say is that you do your pipes under the floor with pragmatism and benefiting from the "no shite" advice I give you. That then opens up what is going on above the floor and gives you options for a system that will work for 50 years and not pelt the asset value of your house. 

Sorry Gus I'll be honest I'm not sure what you mean about designing a system based on what is available above the floor??

 

For clarity: am doing UFH downstairs, and wall mounted fan coils in bedrooms upstairs? Not sure why I would need 'more loops' for FCU cooling? They are on one circuit, drawing water from the buffer?

 

Might have misunderstood though.

[Gus Potter]

On 15/10/2025 at 10:23, SBMS said:

Sorry Gus I'll be honest I'm not sure what you mean about designing a system based on what is available above the floor??

My error. 

 

Anything that is buried in the screed, concrete is permanent. Supposed to last the lifetime of the house. Anything that is above the floor can be changed as technology evolves. As in many things UFH is becoming more mass market, prices for controls, boilers, heat pumps are dropping relative to historic cost. If you think back to the 1970's a TV was a very expensive item relative to income. 

 

My point is. Over design the pipework that is in the floor as you can't change that, call that redundancy. There is debate about whether you should put UFH pipes under kitchen units. What if you later change the kitchen units / move the furniture about or change the flooring for a thicker timber or different materail? 

On 15/10/2025 at 10:23, SBMS said:

Not sure why I would need 'more loops' for FCU cooling?

More loops means less resistance and that gives you the opportinuty to cool things more quickly if the sun suddenly comes out. It does of course work the other way if the temperature suddenly drops. 

 

I'm all for UFH, it's a great way of heating a house, so while at times I may seem overly critical it's often to make a practical point and encourage folk to think about what they want out of a design and, think 10 - 15 years ahead. 

 

[SimonD]

1 hour ago, Gus Potter said:

I'm all for UFH, it's a great way of heating a house, so while at times I may seem overly critical it's often to make a practical point and encourage folk to think about what they want out of a design and, think 10 - 15 years ahead. 

 

 

From the perspective of using heating circuits for cooling with heatpumps, both air source and ground source, it seems to be on trend at the moment and I have to admit I was sucked into this. 

 

I know its popular here on BH, but over the last few months however, I've had conversations with 3 heatpump manufacturer's, all pumps of which can do cooling. Two of them just said they don't recommend it even with fan coils and ufh and with the third, the complexity of getting it to work even with ground source required so much additional plant and complexity, it was ridiculous - e.g. borehole  min 150m deep not ground loop and additional air batteries together with a hydronic design utilising a volumiser and the dhw cylinder to dump excess heat. And then there are the controls, some of which already require subscriptions for users and professionals. God knows what this would all be like after 10-15 years. This one was a very clever design, but might as well go home and get a multi- split unit for the short periods it's really going to be used! 

 

Long term I think its better to focus on passive cooling designs of the house and only then add minimal additional active measures.

 

[JohnMo]

8 hours ago, SimonD said:

complexity of getting it to work

@SimonD this isn't a criticism of what you wrote, more a criticism of industry in general. And a less than pragmatic approach to cooling. 

 

Think the issue when you speak to big manufacturers, is they see a flow temp of a set goal, it really doesn't need to be. So complex isn't really needed. But it's difficult to set practical expectations and sell something. It has to do x or it fails. So manufacturer fall into the camp of you can have cooling, but we do not recommend you use it.

 

I can understand some complexity with a gshp if you want to actively cool below ground temp. But you can cool with gshp at ground temperature plus a bit for losses through the heat exchanger. So effectively have the heat pump off and circulate ambient water and use ground as a heat dump. Actively charge ground with excess heat from the house. Not sure you need anything else, other than a heating system for that. 

 

Our first year in the house, mid summer the water in floor was at 24 degs. Our house just stayed too warm all the time.  Anything that allows circulation to remove floor to a heat dump is good, a bog standard GSHP will do that. An ASHP with cooling will do that.

 

ASHP you just run everything above dew point. The two temperatures proposed here by the OP, is just complexity for the sake of it. You set a single flow temp and let the ASHP manage it based on return temperature or you add a thermostat for cooling and let that call the heat pump into action (£50 or less has that sorted). Your fan coils will have a temp sensor that modulates fan speed, so if room is to hot or cool, fan speed will correct that. UFH as long as the floor surface temperature is below 20 it will actively pull heat from the rooms.

 

Flow temp set point depends on depth of modulation and cycling, a well sized heat pump that will run hours on end, you set flow to about 14 to 16, a heat pump that is oversized will cycle and run about 20 mins you can actually set to about 12 degs. You don't even need a weather comp curve as it gets in the way due to dew point.

 

The above is not Aircon, but makes for a more comfortable house, it cools quicker at night if you suffer from solar gain, which is the whole point. Manufacturers just see cooling as Aircon and the barriers go up. Which isn't helpful or practical.

 

My advise if people want Aircon buy Aircon and live with the constant drying of the air and a draft 24/7. If you want a more comfortable house in the summer, switch your floor to cooling, it isn't perfect but costs nothing to implement and if you have PV nothing to run.

[SimonD]

1 hour ago, JohnMo said:

Manufacturers just see cooling as Aircon and the barriers go up. Which isn't helpful or practical.

 

I think you pretty much hit the nail on the head with your post here. The discussion I was having re the gshp was also together with another installer and what came to light was a fundamental misunderstanding about the meaning of cooling such it meant aircon and would work like aircon.

 

This manufacturer had 2 options - 1 the simple passive approach not too dissimilar to what you describe albeit with some caveats (e.g. still a bore hole and not really considering the dynamic behaviour of ground temperature after a winter heating cycle in a loop etc.) and variations, and 2 the active version, which is more of an attempt to move in the direction of aircon like cooling.

 

The other manufacturer of ashp, the first person I discussed it with dismissed it under the same assumptions due to only being able to achieve a room temp drop of about 3-4C in the particular circumstances, but that drop can make a huge difference to the comfort of the indoor space.

 

I still think it should all fundamentally go back to the fabric first approach and use primary resources at design and build stage (just like the BH mantra on insulation and airtightness) to implement passive cooling strategies which are then supplemented by a passive heatpump 'mild tempering' of indoor temperatures.

 

In the industry, customers are asking more and more about cooling, so it's going to be a growing issue, potentially with lots of disappointment and difficulties like in the OP.

 

[jack]

10 hours ago, SimonD said:

From the perspective of using heating circuits for cooling with heatpumps, both air source and ground source, it seems to be on trend at the moment and I have to admit I was sucked into this. 

 

I know its popular here on BH, but over the last few months however, I've had conversations with 3 heatpump manufacturer's, all pumps of which can do cooling. Two of them just said they don't recommend it even with fan coils and ufh and with the third, the complexity of getting it to work even with ground source required so much additional plant and complexity, it was ridiculous - e.g. borehole  min 150m deep not ground loop and additional air batteries together with a hydronic design utilising a volumiser and the dhw cylinder to dump excess heat. And then there are the controls, some of which already require subscriptions for users and professionals. God knows what this would all be like after 10-15 years. This one was a very clever design, but might as well go home and get a multi- split unit for the short periods it's really going to be used!

 

I've used underfloor cooling for nearly 10 years (didn't use it the first two or three years after we moved in) with great success and zero issues.

 

Panasonic's UK technical team were hugely supportive while I was trying to get the ASHP working efficiently in UFH mode, but they were very cold (pardon the pun) on the idea of underfloor cooling. I think there's just a strong bias in the undustry against it, probably due to a combination of risk-aversion and ignorance.

If you're only planning to use it now and again when the heat build-up in the house is getting too much, it literally needs nothing other than a switch, or maybe a timer, connected across the ASHP "cool" terminals.

 

Our system is slightly more complicated, because I control it with our home automation system, but it's still fundamentally just acting as a smart timer. All it does is close two relays when certain conditions are met, one of which puts the ASHP into cooling mode and the other of which turns on the UFH pump. You could do similar with a timer and thermostat.

 

Our UFH is run as a single zone downstairs, with the water temp set at 15 degrees.  

 

Never had a moment's problem with this setup. We get a whisp of condensation on the exposed metal parts of the UFH manifold, but that's it. No need for complex controls or subscriptions etc. I can't imagine how it could get any simpler.

 

58 minutes ago, SimonD said:

The other manufacturer of ashp, the first person I discussed it with dismissed it under the same assumptions due to only being able to achieve a room temp drop of about 3-4C in the particular circumstances, but that drop can make a huge difference to the comfort of the indoor space.

 

I still think it should all fundamentally go back to the fabric first approach and use primary resources at design and build stage (just like the BH mantra on insulation and airtightness) to implement passive cooling strategies which are then supplemented by a passive heatpump 'mild tempering' of indoor temperatures.

 

Fabric-first is important, for sure.

 

We have exterior blinds on most windows that benefit from them, PassivHaus-class insulation and airtightness, and good overhangs on many east-, south-, and west-facing windows. Even with all that, upstairs bedrooms can easily get into the high 20s during long periods of hot weather. That comes down a bit with the downstairs underfloor cooling on. The ground floor can easily be held at a comfortable 20-21 degrees.

 

I obviously don't know what downstairs would be like if we had no underfloor cooling, but I can tell you how lovely it is to walk downstairs in the morning during hot weather. It's like walking into a cave or a cathedral. The cool floor sucks the heat out of your feet, which is a very pleasant way of staying cool.

 

Having spend many years living in a hot country, I really dislike the way aircon dries the air, so for me, underfloor cooling is just a no-brainer.

If I were building again, I'd personally consider installing UFH under tiles on a thin screed upstairs and cool that during summer. During winter, I'd put rugs down and maybe run the UFH just enough to keep the chill off if needed during the coldest spells.

 

The only thing I'd add is that all forms of underfloor heating and cooling will be more effective if the floor is made of a thermally conductive material such as tile or concrete. Wood isn't as good, and I guess even low-TOG carpet is worse again.

[-rick-]

11 hours ago, SimonD said:

the complexity of getting it to work even with ground source required so much additional plant and complexity, it was ridiculous - e.g. borehole  min 150m deep not ground loop and additional air batteries together with a hydronic design utilising a volumiser and the dhw cylinder to dump excess heat.

 

Not sure I understand why they said any of this. It's been a while since I looked but when I was looking I'm pretty sure I saw plenty of examples of shallow depth (1m) coils being set up for heating and cooling without a problem (I was tending to look at other countries as not so much used here). The problem with them is sometimes you need a lot of space/length to stop them freezing in winter, not a problem to dissapate excess heat in summer.

 

DHW cylinder to dump excess heat sounds like they've gone way off topic.

 

2 hours ago, JohnMo said:

I can understand some complexity with a gshp if you want to actively cool below ground temp.

 

Sorry, I feel I'm missing something here. If you use a GS heat pump to cool a property the heatpump is actively heating the ground during this time. The problems with ground source I thought were more with the ground freezing when you try to pull too much heat from it during winter. Didn't think adding heat to the ground during summer was a big issue comparitively.

 

2 hours ago, JohnMo said:

But you can cool with gshp at ground temperature plus a bit for losses through the heat exchanger. So effectively have the heat pump off and circulate ambient water and use ground as a heat dump. Actively charge ground with excess heat from the house. Not sure you need anything else, other than a heating system for that. 

 

This was my understanding and it's commonly used and supported in other countries. Though I'm sure I've also seen plenty use the heatpump for greater effect. As at least in some ground conditions it helps recharge the ground for the winter heat demand.

[JohnMo]

47 minutes ago, jack said:

I can't imagine how it could get any simpler

 

48 minutes ago, jack said:

and the other of which turns on the UFH pump. You could do similar with a timer and thermostat.

If no additional pumps that can be deleted. I just have summer winter switch - that's it and leave it to get on with it. 

 

49 minutes ago, jack said:

It's like walking into a cave or a cathedral.

A good analogy.

50 minutes ago, jack said:

ground floor can easily be held at a comfortable 20-21 degrees.

Our does get warmer than that at peak solar gain, but still has that cathedral feel, all the heat being suck away from you.

 

52 minutes ago, jack said:

I'd personally consider installing UFH under tiles on a thin screed upstairs and cool that during summer

A better option may be ceiling cooling - same as UFH but in the ceiling.

 

51 minutes ago, -rick- said:

Sorry, I feel I'm missing something here.

Most GSHP aren't reversible, but can act as a passive (ish) heat dump. So complexity comes making them act in reverse 

[-rick-]

1 minute ago, JohnMo said:

Most GSHP aren't reversible, but can act as a passive (ish) heat dump. So complexity comes making them act in reverse 

 

Ah, trying to make something that wasn't designed for it do cooling. I thought we were talking about things that did support it but the manufacturer didn't recommend.

[jack]

11 minutes ago, JohnMo said:

If no additional pumps that can be deleted. I just have summer winter switch - that's it and leave it to get on with it. 

 

True if you're using a controller with a pump output that switches on when there's a call for heat/cool.

 

In my setup, the UFH pump is separately controlled to turn on in various scenarios, including when the heating or cooling is on (with an over-run after it turns off), and when the slab temp is above a certain temp (mainly to distribute heat from floor areas that are in direct sunlight).

 

11 minutes ago, JohnMo said:

A better option may be ceiling cooling - same as UFH but in the ceiling.

 

I've considered that too. My guess is that it would be particularly effective for cooling, because a lot of heat in the summer comes through the ceiling, so preventing that it probably a good option. 

 

I have more concerns about condensation in that scenario, but that's largely based on my complete ignorance of how such systems are actually installed. I'm assuming no-one's installing a self-leveling screed or slab in their ceiling!

[SimonD]

18 minutes ago, jack said:

I'm assuming no-one's installing a self-leveling screed or slab in their ceiling!

 In Europe there are a few companies selling wet ceiling units where ufh is impractical, and for walls. Apparently the ceiling units work even better than ufh, but I haven't had the opportunity to find out in person yet.