Outside heat pump element in the inside (well, so to speak): should this work?

[Garald]

I'm trying to get the architect to agree that her plans will not work. Of course she is saying now that changing plans at this late stage will result in delays, higher fees (to her...)

 

In the end, I suspect the compromise solution will not be to install the fan on the roof (which would, she tells me, necessitate reinforcing the roof structure, permits from town hall, etc.) but installing it on the courtyard. She had already studied the matter and concluded that one can do it in such a way that sound regulations are respected.

 

Does this seem like a good plan, given the dimensions of the courtyard (see above)?

 

Would having the fan be 1m from the floor (say) help in any significant way?

[SteamyTea]

15 minutes ago, Garald said:

I suspect the compromise solution will not be to install the fan on the roof

You can get split ASHPs.

The fan unit should have less mass than a monoblock, and the 'pump' unit can go in the shed/outbulidling.

Edited December 1, 2022 by SteamyTea

[Garald]

39 minutes ago, SteamyTea said:

You can get split ASHPs.

The fan unit should have less mass than a monoblock, and the 'pump' unit can go in the shed/outbulidling.

 

Yes, I take it for granted that this is what is meant. I will confirm.

[Garald]

Now I am in "getting my architect to accept reality" mode. She is telling me that "there is theory and there is practice" - right, but that goes in the other direction! Something may work in theory and fail in practice, but if something fails utterly in theory, then it will certainly fail in practice! (I didn't tell her that yet.)

 

She says (I translate):

"I understand the arguments [...] but I advise you to listen the arguments of Mr. I., who didn't doubt it would work [NB: he has arguments?], as well as several technicians with whom I talked at Interclima [a trade show at the beginning of October]. (Please note that for the moment he is the only competent installer who is available, and I've been looking for one since July.)

 

I have no experience with heat pumps, but I have already installed many external AC units in this kind of configuration and they have worked perfectly for a long time."

 

How do I explain the difference - is the main part that the amount of air being pumped through a heat pump is much greater than that pumped through by an AC unit? The idea that a heat-pump is mainly an AC running in reverse may have played her a dirty trick.

 

"If, contrary to the professionals [who precisely - Mr. I, the technician who agreed to install a heat-pump fan in this bizarre configuration?] you think that 8kW is enough, Atlantic has a kit for interior installation:

 

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

"

 

Questions:

(a) how do I do the heat calculation for the whole triplex apartment? (I have only seen the spreadsheet for a single room, which presumably could be used for one level of the house.)

(b) What do you think of this kit? It looks like something roughly in the direction of what IanR was saying.

 

(Then she asks whether I want a supplementary study and what would be the deadlines and the price. Quite aside from the fact that I don't know how I feel about paying someone for correcting his or her own mistakes, after having paid him or her for making them, I really feel I should be asking someone else about this matter, and let her take care of ventilation (which is what she does best) and everything else. Does anybody know a heat-pump installation specialist in the Paris area?)

Edited December 1, 2022 by Garald

[Marvin]

My comment:

 

 

 

May be an ASHP needs a bit more room than a room!

Edited December 1, 2022 by Marvin

[SteamyTea]

Here is the MCS spreadsheet.  Not looked at it in detail, but it is what official installers have to use here.

 

https://mcscertified.com/wp-content/uploads/2021/04/MCS-Heat-Pump-Calculator-Version-1.10-locked.xlsm

[Garald]

10 minutes ago, SteamyTea said:

Here is the MCS spreadsheet.  Not looked at it in detail, but it is what official installers have to use here.

 

https://mcscertified.com/wp-content/uploads/2021/04/MCS-Heat-Pump-Calculator-Version-1.10-locked.xlsm

 

Thanks! Not sure what to do about the first page. Shall I pretend Paris is Hurn? Where do I need to enter that?

[HughF]

I’ll give you a link to the 2021 revision of the freedom heatpumps spreadsheet when I’m in front of my computer. It’s nice and simple to use.

 

There is also heatpunk from midsummer wholesale, this is a web based system and you can sign up for a free account.

[Garald]

52 minutes ago, HughF said:

I’ll give you a link to the 2021 revision of the freedom heatpumps spreadsheet when I’m in front of my computer. It’s nice and simple to use.

 

There is also heatpunk from midsummer wholesale, this is a web based system and you can sign up for a free account.

Thanks in advance!

[HughF]

Attached is the Freedom Heatpumps installer/specifier toolkit spreadsheet - you change the items in the blue cells. There was a video online showing how it worked, but that has since been taken down.

 

Heatpunk can be accessed through: https://heatpunk.co.uk/home

 

You will need to make a free account. A video showing how to use it is: 

 

1451167288_2021FreedomHeatPumpstoolkitV3.3forallinstallers-Copy.xlsx

[Garald]

Thank you very much!

 

If I want to explain to the architect (who said "but I installed plenty of ACs in that configuration") what would go wrong (I've already relayed all the arguments above), should I say the following:

 

An AC, by design, recycles air, and thus, if plenty of the air that it has just cooled gets cooled again further, that's not fatal or even necessarily undesirable;

in contrast, in a heat-pump, we are *extracting* heat from outside air; once we have extracted some heat from that air, we want to say good-bye to that air as fast as possible, since it is harder and more expensive (and in fact quickly becomes impossible, given the design of the machine) to extract further heat from already cooled air.

 

(Not to mention that a 11kW heat-pump pumps almost an order of magnitude more air per minute than a medium-sized AC, no? But that's a different matter.)

 

This is apparently an object lesson of how "a heat pump is inverted AC" is a bad metaphor, or at least one that can be very misleading when pushed.

 

Edited December 2, 2022 by Garald

[SteamyTea]

35 minutes ago, Garald said:

if plenty of the air that it has just cooled gets cooled again further, that's not fatal or even necessarily undesirable;

Except some A/C units do not recycle cooled air.  Many are work just the same and just use external air only for the thermodynamic cycle.

 

37 minutes ago, Garald said:

object lesson of how "a heat pump is inverted AC" is a bad metaphor

It always has been, I hate it when  an ASHP is referred to as a 'fridge in reverse.

 

Really a case of asking your venting architect to do some sums and show that the unit will have sufficient airflow without affecting performance.

She will probably only believe her own figures. 

Check her homework though.

[Garald]

1 hour ago, SteamyTea said:

 

 

Really a case of asking your venting architect to do some sums and show that the unit will have sufficient airflow without affecting performance.

She will probably only believe her own figures. 

Check her homework though.

 

I think I'll do my own homework. (Really doubt she did any calculations, in this case.) Her suggested framework will not work, and a hack as in 

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

(in the general direction of what IanR was suggesting)

in such a constrained space is tempting fate (though, if people show me how, I could do the airflow calculations for fun).

 

She reacted quite badly to the suggestion of putting the external unit on the roof, at this late stage in planning (work on the house started weeks ago). Of course permits from town hall would be needed.

 

The one plausible alternative seems to put the external unit in the courtyard (as was our plan B, before the architect was lured into this practically literal trap). I am actually meeting with the only other person in the coop who comes to meetings tomorrow (we have >60% of the votes together), and can try to get his preliminary agreement (he was not against it when we mentioned this plan B to him some time ago).

 

 

Should I do any flow calculations here? It's not as if the courtyard were toilet-sized - you can see its dimensions in the other thread.

(Perhaps the unit should be a bit further away from the wall, or in front of my staircase rather than in front of my bathroom window?)

 

We already checked back in June that the external unit of a Panasonic (with sound protection around it) satisfies sound-pollution regulations, being below ambient noise

- and a Yutaki would be a bit quieter than a Panasonic (the specifications claim 54dB at 1m for the 8kW model and 49dB at 1m for the 11kW, *without sound protection*, which lops off more than 10dB).

 

 

 

 

[Garald]

Here are the dimensions of the courtyard.

[Garald]

14 hours ago, HughF said:

Attached is the Freedom Heatpumps installer/specifier toolkit spreadsheet - you change the items in the blue cells. There was a video online showing how it worked, but that has since been taken down.

 

Heatpunk can be accessed through: https://heatpunk.co.uk/home

 

You will need to make a free account. A video showing how to use it is: 

 

1451167288_2021FreedomHeatPumpstoolkitV3.3forallinstallers-Copy.xlsx 3.66 MB · 2 downloads

 

I'm having a bit of trouble getting the Heatpunk app to understand that I don't own all of the ground-floor, and so some of my walls are not in fact external walls. How do I do that?

 

... and I am having trouble to get the FreedomHeatPump spreadsheet to understand that there are cities no in the UK. Shall I just pretend that Paris is London? It's hotter during the summer, but the two have similar winters.

 

 

[HughF]

5 hours ago, Garald said:

 

I'm having a bit of trouble getting the Heatpunk app to understand that I don't own all of the ground-floor, and so some of my walls are not in fact external walls. How do I do that?

 

... and I am having trouble to get the FreedomHeatPump spreadsheet to understand that there are cities no in the UK. Shall I just pretend that Paris is London? It's hotter during the summer, but the two have similar winters.

 

 

You can tell heatpunk that a wall section is party/internal wall - It should be covered in the video somewhere, I remember doing it for my upstairs party walls.

 

Yes, pretend that Paris is London, the software was only designed for countries in the UK so that's why there isn't any overseas geographical support.

[Garald]

All right, here is my sheet. Tell me if I have done something wrong.

 

I am getting:

[Heat loss if known kW                  6,6 - no idea where this came from; what is this?]

Heat loss calculator figure kW     8,5kWh

Heating flow temperature C         45

I seem to be getting that I need at least 8.5kWh. The eyeballing estimate turned out to be in the right ballpark. (The fact that there are two spots we have not been able to insulate (attic sidewalls and the small corner staircase to the attic) is what brings me over 8kWh.)

 

Does that mean:
- 8kW would not be enough

- 9kW would be enough

- 11kW would be... an acceptable overcalculation? Notice that the Yutaki comes only as a 8kW unit (maximum performance: 11kW) or as a 11kW unit (maximum performance: 15.2 kW)

 

Then I get: "your heat pump is expected to provide 69% of your hot water. You will need additional heating to provide 31% of your hot water."

 

Should I take this seriously? I thought Hitachi Yutakis and Panasonic Compact Aquareas had big, nice water tanks. What is the limitation here?

 

(Also, what about cooling? Yutaki, Panasonic, etc. are reversible.)

 

309760954_Myheatinglossworksheet.xlsx

Edited December 4, 2022 by Garald

[JohnMo]

Per reply in other thread.

 

I think if you get your ventilation heat loss sorted the DHW will be fine.  Also this is a calculation for your lowest day temperature.  You have an immersion should it be required to heat water.

 

With a heat pump making it large/oversized to suit the worst day of the year, makes it huge at all other times.  On a 10 deg day when your heat load is less than 1kW, a huge heat pump has no chance of being efficient without a huge buffer.

[JohnMo]

Perspective

3 person household consumption of DHW is 5kWh

Number of design days per year, very few.

31% of 5 x very few, is not much, full cost electric for an immersion.

[SteamyTea]

11 minutes ago, JohnMo said:

3 person household consumption of DHW is 5kWh

Number of design days per year, very few.

31% of 5 x very few, is not much, full cost electric for an immersion.

The legionella cycle is going to take up that difference I would have thought.

If I 'overheat' my cylinder, it lasts about 3 days (200 lt at ~50°C usually, up it when friends stay to 65°C, then forget to turn it down again).  My total mean water usage is 150 lt/day.

[Garald]

Here is the corrected worksheet. I've left heat recovery efficiency at the default value of 66%. I will have a positive-input single-flux (VMI Purevent) that I *think* does something that amounts to heat recovery, in some sense? I don't really know what value I should input. What would be a reasonable guess?

 

At any rate, with 66% (which may be optimistic), I get 5,2 kWh. With 0%, I get 6,2 kWh.

 

The bizarre thing is that the system still tells me: "your heat pump is expected to provide 69% of your hot water".

 

(For the record - at least half of the time in the immediately foreseeable future, I'll be leaving alone; at other times, girlfriend and/or my parents will be visiting for more or less extended periods. None of us are amphibians.)

 

 

629771879_Haraldsheatlosscalculation-corrected.xlsx

[ReedRichards]

You need to allow the heat pump time off from heating your house to allow time for heating your hot water and for defrosting in cold weather.  My heat loss was calculated to be 8.95 kW at - 3.7 C.  But if my heat pump takes two hours a day off doing other things then it only has 22 hours with which to heat my house so the output capacity I would need would be 8.95*24/22.  In actuality I got a 12 kW heat pump.  

[JohnMo]

Your calculation for heat loss is now 5.2kW, considerable drop

[Garald]

Well, 5.2kW if it had heat recovery, 6.2kW without. What I will have is a VMI-Hydro'R system (https://www.ventilairsec.co.uk/products/hydro-r/). It is a positive-input system that does not have heat recover as such, but, rather, that water produced by the heat-pump preheats the air being distributed throughout. The manufacturer website claims that this is done "without extra energy", but that's of course physically impossible; still, we can presume the process is somewhat more efficient than radiators, since otherwise there would be no point to its existence. Let us say, very conservatively, that my needs are really 6.2kW, in that this system helps a little bit. (Do you think it helps more than that?)

 

At any rate, what does this mean in practice? Is a 8kW pump fine or too little? As I said, I'll be living alone at least half the time in the near future, but a scenario in which two people take showers on different floors at the same time is more than possible (in fact it could in principle happen that two people take showers while one takes a bath, though we aren't sirens or anything). Is a 11kW pump too much?

 

I've read a 8kW pump can be a bit tight for *cooling* in a place this size, but I suppose that's the case if one has lots of fan coil units. I'm not sure I'll have any - the basic plan is to get cooling *only* from the VMI-Hydro'R system (though we could follow the advice here and install, at the very least, the ducts needed to install a fan-coil unit in the attic and another in the main south-facing room (the long library, which is the central part of the apartment)).

 

[SteamyTea]

3 minutes ago, Garald said:

but a scenario in which two people take showers on different floors at the same time is more than possible

Just put in one, larger shower, large enough to squeeze two bodies into.

Been years since I have had someone scrub my back, one disadvantage of living alone.