(Hitachi) Air-water heat-pump: use for cooling?

[Garald]

Another chapter in the renovation saga!

 

(As some people know, we are carrying out a major renovation of a duplex near Paris dating from 1930. Proper cellulose and reflective insulation everywhere, new radiators adapted to low-temperature heating (keeping some of the old ones), ...  We already cut off the gas, and are trying to choose an air-water heat pump. We've bought a broken-down courtyard outhouse from the coop so that we can put the "outside" part inside and not bother the neighbors.)

 

We are now inclined towards the Hitachi Yutaki S 2.0 heat-pump, as opposed to the Amzair Optim'Duo, mainly because the company that was going to sell us the Amzair dropped the ball and didn't get back to us with a precise quote. (There's also the fact that the parameters for the Yutaki are somewhat better. It also looked originally as if it was going to be a lot cheaper, but given how much the installer wants to charge us for this and that, I am not sure that this is still true.)

 

Now, the website for the Hitachi Yutaki 2.0 emphatically states that it can also be run backwards, for cooling in the summer.

 

How would that work for an air-to-water heat-pump? Is that only for people who have underfloor heating (I am not one of them)? Or can the heat-pump really cool water (up to what temperature? not clear from the documentation!) that can be simply circulated around the radiators just as one circulates hot water?

 

What measures do I have to take in practice?

Edited November 19, 2022 by Garald
typo

[akjos]

In cooling the heatpump will run the refrigerant in reverse in a way and dump heat outside while cooling your water in the heat-exchanger.

 

You can then use the cool water for cooling. UFH is better suited for this as the surface area is large. With radiators you might not see a big difference.
 

The most important thing is not cooling the water below your dew point as then you will have condensation on your pipes and potentially horrible water damage (mold, rot…). So always see what your dew point is (calculate it with your relative humidity and temperature) and run the water above that.

From what i see in the Yutaki documentation, it can cool the water to 7’C degrees. You will also need the additional cooling accessory kit, but I think that’s just an electrical pin which activates the function.

A better way to cool if you don’t have UFH is to pipe an additional water pipe with a zone valve to a fancoil unit installed in the rooms you want to cool. The fancoil unit cools the air with the cool water from your HP and blows it into your room. It also has a condensate drain, and you can use it for heating too if you wanted to.

Edited November 19, 2022 by akjos

[nod]

We’ve spoken to several companies and all have advised against for the above reasons 

[JohnMo]

If you search on here someone tested cooling on a radiator, it was unsuccessful, as it cooled the bottom few mm only

[Radian]

Radiators are really convectors and run 'in reverse' will just chill the air around them and create a cooler layer down on the floor. Plus a pool of water from condensing out the water vapour as @akjos says. A fan coil unit gets round both these issues by circulating the air where its more useful and harmlessly drain away any condensation.

[Garald]

Nice - mystery solved!

 

Where does one install a fan-coil unit? Near the ceiling? (Does it make sense to install one above the chimney?) Is one enough for cooling a rather long room (40m² total)? I don't think I've ever seen a fan-coil unit. Seems to take quite a bit of space (one of the reasons why we decided against getting an air-air heat pump to begin with). Is noise an issue?

 

I guess I can put one in the library and one or two in the converted attic. I wonder where in the attic such a unit can go! (We are redoing the floors, but I think the architect will freak out if I suggest UFH for the attic - there already isn't a lot of space where one can stand upright. Is UFH something one can choose to have on a single floor or even a single room and not elsewhere, within one and the same low-to-moderate-temperature heating system?)

 

I've found the long thread here:

 

In the end, what are some units available within the EU that have a good quality/price ratio and are not noisy or bulky?

 

(Hitachi does seem to make a FCU itself, but it seems evident (from size, price, etc.) that it is meant for the industrial sector.)

[Garald]

PS. So, a radiator cannot be used for cooling - but can a FCU be used for heating as well as cooling? That could save us some space and money. Of course there's still the noise issue.

 

The French term for "fan coil unit" I am finding is "ventilo-convecteur", and it seems to be used mostly for heating.

 

[Radian]

28 minutes ago, Garald said:

can a FCU be used for heating as well as cooling?

Certainly. I'd concentrate with locating them in higher positions, in rooms with most solar gain in the summer. The cool air will naturally descend to lower regions. In winter these lower locations might be better heated by UFH but the FCU's can still play a part. The key to comfortable heating will be investing in systems with good quality fan control. The best A/C units adapt the flow according to occupancy detectors. I don't know if this is featured in any FCUs. I'd advise getting a demonstration of any units your were thinking of buying. A few minutes in front of one will give you a good impression of what it would be like in terms of noise and airflow.

[ReedRichards]

Hello @Garald, I was wondering what had become of you.

 

I know nothing of FCUs but with a quick search online I could not find anything that did not look ugly and industrial.  Surely with your classy Parisian apartment you would want something stylish in keeping with the decor?

[Garald]

36 minutes ago, ReedRichards said:

Hello @Garald, I was wondering what had become of you.

 

The destructive phase of renovation is coming along wonderfully. If you want recent pictures of things being taken apart, please tell me.

 

36 minutes ago, ReedRichards said:

 

I know nothing of FCUs but with a quick search online I could not find anything that did not look ugly and industrial.  Surely with your classy Parisian apartment you would want something stylish in keeping with the decor?

 

That's an issue. Some of the Panasonic ones do not seem too bad:

 

https://www.aircon.panasonic.eu/FR_fr/product/aquarea-air-radiators-1-1/

 

(Alternatives?)

 

Would one be enough for cooling a long 40m² library(/piano room/dining room/everything else) with southern exposure? I might place it above the fireplace that doesn't work (putting it above the fireplace that does work would seem a bit bizarre, particularly since, if it ever gets under -10 C again, I might have to recur to using both the FCU (for heating) and the fireplace).

 

BTW, might try to ask someone who sells Panasonic heat-pumps to provide a quote for a heat-pump while we are at it. All the Hitachi FCUs I see are ugly, industrial and extremely expensive. Of course I don't foresee any problems combining a Hitachi heat pump with a Panasonic FCU (should I?).

 

1 hour ago, Radian said:

Certainly. I'd concentrate with locating them in higher positions, in rooms with most solar gain in the summer. 

 

Well, that would be 

- the library

- the attic (no idea where to put the unit then!)

- come to think of it, the kitchen, whose floor we have just taken apart (should we consider putting underfloor heating and cooling there? would it be very expensive? If it replaces the radiator, it would free up a cabinet's worth of space in what is after all a small kitchen. Note it is right above a coop corridor (whose ceiling we are or were about to insulate).

[Garald]

PS. If we were to go for underfloor heating in the kitchen, how does that restrict our choice of flooring? (Restrictions in the choice of flooring (wood vs. stoneware tile vs. geometric patterns in rustic multi-colored terracotta vs ecuran) would be welcome; as you may know from another thread, this is right now a case of Buridan's ass getting screamed at by the other animals in the barn.)

 

PPS. How would the system work overall - is it simple to set up things so that water would circulate to all radiators and possibly to all FCUs during the winter, but only to the FCUs during the summer?

Edited November 19, 2022 by Garald