Yet more heat-pump adventures: the courtyard won't do. In garage, input from the street?

[Garald]

So, yet further heat-pump adventures. Last week, a technician visited - he seemed very reasonable. Unfortunately, we just got the same answer that we got a little earlier from another installer: his company will not install the external unit on the shared courtyard, to avoid liability due to noise.

 

We could try to find yet another installer (as the company suggests) but we are already seeing a pattern here. It may be wise to reexamine our choices.

 

We can't of course have a setup where input air and output air mix indoors - that's what the architect had in mind in October and November, but that is madness (as became clear as soon as I got precise information from her and I posted it here).

 

The question is then whether we can have a setup where the heat-pump takes air directly from the exterior, and outputs colder air (in winter) to the interior. It seems wisest from many points of view to do this in the (small) garage (which is gradually becoming a bike shed/ex-garage, anyhow), which faces the street, rather than in some sort of closet facing the courtyard, as in the doomed October-November plan.

 

It would be something more or less like this (from her old plans):

 

Now, the version of the plan here shows an Amzair Monobloc (https://www.amzair.eu/nos-pompes-a-chaleur/pompe-a-chaleur-optim_duo-2/) which is not ideal from several perspectives (very expensive, COP not among the best, not among the quietest heat pumps - since the garage faces the street, that's no longer a concern for the neighbors, but it may be a concern for me, since my main room (library/piano room/...) sits right above the garage). The fact that it is a monobloc is also no advantage - it might make hooking it up to the VMI more complicated (should consult the architect again on that one).

 

One alternative is to have a split heat-pump, and have the "outside" element attached to the opening of the garage, much as the above. That is possible, and in fact there is a (most likely overpriced) kit in the market for doing so:

 

https://www.atlantic.fr/Chauffer-le-logement/Pompe-a-chaleur/Aerothermie/Aerothermie-Air-Eau/Wall-In

 

As it says, it works up to 8kW, but that should be more than enough - the spreadsheet gives me a total heat loss of 5.3kW at outside temperature = -2C.

 

Questions:

 

(a) Should this work well? The input would come directly from the street (presumably as high up from the ground as possible), the output would go into the garage (which would presumably have to have a ventilation grille further down to allow cold air to come out, even though that's not shown on the website; in fact I'm having a hard time seeing where the air goes out of the box). The garage would presumably be very cold, so we would have to insulate the garage well (heat and sound), on the ceiling and on the "upper" and "left" walls of the garage on the plan (my laundry and the medical cabinet next door, respectively). Is performance likely to be affected?

 

(b) This is a proprietary system fitted to work with the company's (Atlantic) own products. The technical specifications for the Alfea Extensa 8 R32 do not seem bad (https://idealheating.com/new-build/products/alfea-extensa-a-i-r32), though they do not seem to indicate how much indoors noise the unit produces when fitted in with the proprietary system.  (I'd have to see as the total cost - notice it does not come with a hot water tank). At the same time, it would seem logical that there should be products that work with other heat pumps, including ones that are particularly quiet (Saunier-Duval aka Vaillant, for instance, or Mitsubishi Zubadan). Are there any?

 

Thoughts?

 

Edited January 24, 2023 by Garald

[Nickfromwales]

Why not partition the end of that room off and create a 'wind tunnel'? Eg with the full eternal door being a large louvre / transfer grille? Have the heat pump sucking air in through the transfer grille ( external door ) and then exhaust it back to outdoors through a second grille in the outside wall ( which connects the front of the HP to atmosphere via a sealed duct ).

You then install a second door into the new partition wall to get access into the 'garage'.

Your climate is 'different' to ours, but in the UK we'd certainly NOT want to be positively pressurising the dwelling with cold / damp air from atmosphere.

[Garald]

2 minutes ago, Nickfromwales said:

Why not partition the end of that room off and create a 'wind tunnel'? Eg with the full eternal door being a large louvre / transfer grille? Have the heat pump sucking air in through the transfer grille ( external door ) and then exhaust it back to outdoors through a second grille in the outside wall ( which connects the front of the HP to atmosphere via a sealed duct ).

You then install a second door into the new partition wall to get access into the 'garage'.

Your climate is 'different' to ours, but in the UK we'd certainly NOT want to be positively pressurising the dwelling with cold / damp air from atmosphere.

 

Paris is pretty much London up to a first-order approximation.

 

I still need to be able to access the garage from the street (pretty much as in the plan above), since it will become a bike shed.

[Nickfromwales]

1 minute ago, Garald said:

 

Paris is pretty much London up to a first-order approximation.

 

I still need to be able to access the garage from the street (pretty much as in the plan above), since it will become a bike shed.

Ah, ok. Then you absolutely do not want to be pressurising the house with air taken from the street!!

You will still have access, as the door doesn't 'go', it just becomes a transfer grille.

Or, if you can, make 2x transfer grilles; 1 up high for inlet air, and a lower one for exhaust. The partition section becomes a 'wind-tunnel'.

[Garald]

1 minute ago, Nickfromwales said:

Ah, ok. Then you absolutely do not want to be pressurising the house with air taken from the street!!

You will still have access, as the door doesn't 'go', it just becomes a transfer grille.

Or, if you can, make 2x transfer grilles; 1 up high for inlet air, and a lower one for exhaust. The partition section becomes a 'wind-tunnel'.

Yes, I was suggesting precisely to have 2 transfer grilles as you say. But what sort of partition section and "wind-tunnel" do you have in mind? Can you draw a sketch?

[Nickfromwales]

1 minute ago, Garald said:

Yes, I was suggesting precisely to have 2 transfer grilles as you say. But what sort of partition section and "wind-tunnel" do you have in mind? Can you draw a sketch?

Just create a stud partition wall 1200mm behind the external wall, parallel with it, with a second secure door to the house. The interior of that new space would need lining with a suitable material ( maybe uPVC cladding etc ) and air would just take the path of least resistance. Ergo the input grille would ideally be 20-30% bigger than the exhaust so you dont pull air from the dwelling.

A drawing can follow, but family business awaits atm.

[Garald]

Well, we have something more or less like that, in that the door between the garage

2 minutes ago, Nickfromwales said:

Just create a stud partition wall 1200mm behind the external wall, parallel with it, with a second secure door to the house.

 

 

Well, we have something more or less like that, in that the door between the garage and the laundry ("buanderie") is a secure metal door; thus, the entire garage is pretty much a larger version of what you have in mind. Is that not enough? Is that a bad idea for some other reason?

[AliG]

I have looked at the technical specs of the heat pump, but cannot see an installation manual.

 

From what I can see, like most heat pumps, it is designed for air to be drawn in at the back and blown out the front. This is why they are normally placed a few hundred mm from an outside wall, facing away from the house.

 

The suggestion here seems to be to mount it "backwards" so that it draws air from the street and blows it into the garage space.

 

Similar to @Nickfromwalessuggestion, but simpler would be to move the wall and door in around 800mm from the street (allows for 300mm clearance behind plus the depth of the heat pump). Then the unit could be mounted as normal in that space facing the street, taking air in from behind and blowing cold air out into the unrestricted street. No need for grilles. If it needs clearance to one side you would mount it with the door at that side.

 

TBH looking at the spec, the concern re noise is incorrect. We have just installed a Panasonic Aquarea ASHP for my parents and you can barely hear it is running standing right next to it. The days of noisy heat pumps are well behind us.

[Garald]

29 minutes ago, AliG said:

Similar to @Nickfromwalessuggestion, but simpler would be to move the wall and door in around 800mm from the street. Then the unit could be mounted as normal in that space facing the street, taking air in from behind and blowing cold air out into the unrestricted street.

 

This is an urban area, so major changes in outer appearance are very iffy. We'll have to ask for planning permission even for the change to the door, installing a grille, etc. 

 

29 minutes ago, AliG said:

 

TBH looking at the spec, the concern re noise is incorrect. We have just installed a Panasonic Aquaria ASHP for my parents and you can barely hear it is running standing right next to it. The days of noisy heat pups are well behind us.

 

The big problem is that (at least here in France) installers are still very concerned about noise, due to liability. The ideal thing from many points of view would really be to install a quiet (Saunier-Duval/Vaillant: much quieter than Aquarea) heat-pump in the back courtyard. However, we just got a second refusal from an installer, as they are concerned that they would be liable if neighbors complained. It is really a pity, since we are most likely going to get authorisation from the coop this Saturday to install a heat-pump in the courtyard.

Edited January 24, 2023 by Garald

[Nickfromwales]

1 hour ago, AliG said:

We have just installed a Panasonic Aquarea ASHP for my parents and you can barely hear it is running standing right next to it. The days of noisy heat pumps are well behind us.

Same weapon of choice here. I'm blown away by how quiet they are for the money. Easily as quiet as the Stiebel Eltron units ( which command a LOT more of your hard earned ).

 

1 hour ago, Garald said:

The big problem is that (at least here in France) installers are still very concerned about noise, due to liability. The ideal thing from many points of view would really be to install a quiet (Saunier-Duval/Vaillant: much quieter than Aquarea) heat-pump in the back courtyard. However, we just got a second refusal from an installer, as they are concerned that they would be liable if neighbors complained. It is really a pity, since we are most likely going to get authorisation from the coop this Saturday to install a heat-pump in the courtyard.

Can't you provide them with a written waiver, stating that you will meet any subsequent removal costs etc if it all goes south? Once it's in, show the installers how quiet it is and they'll get a very much needed education.

[Garald]

Was just on the phone with another installer (one who works with Mitsubishi). He may be able to do it, but, even though I've told him that total heat loss comes out at 5,3kW, he wants to install a 12kW system. I've started to try to convince him otherwise, but I suppose beggars can't be choosers. Still, as I was telling him, that compounds the other problem: the difference between the 8kW and the 12kW in the Mitsubishi models is 4dB (he said), and that, I told him, is actually a big difference (10^0.4 > 2.5, i.e., one is at least 2.5 times louder than the other).

[Garald]

Also found one that works with Atlantic, but that's not so quiet (the external unit produces 60dB).

[Dave Jones]

hang it off an exterior wall/put it on the roof.

[Garald]

1 hour ago, Dave Jones said:

hang it off an exterior wall/put it on the roof.

 

Still trying to find an installer who will agree to an exterior installation (thpugh there are some good initial signs). On the roof - yes, I agree, but that's something the architect and I discussed in June, and she freaked out when I brought that up six weeks ago.