Advice on ASHP choice needed
Posted by: @derek-mIt should also be noted that the actual heat loss of bedrooms can be lower than the calculated value, due to heat rising and solar gain through the roof.
Excellent observation @derek-m, modern well insulated homes with low infiltration/exfiltration AC/h values tend to suffer from overheating upstairs. This is due to simple physics with warm air being less dense and rising in the heating season. Modern lifestyle factors compound this, such as increasing preference for open plan living and larger hallways, stairs and landings, or atriums, where warm air can easily rise.
Non-scientific estimations by myself seem to show the upstairs of uniformly heated two storey dwellings can be 2degC warmer than downstairs. We can usually turn down heat output upstairs, but what if there's a heating capacity shortfall downstairs, or the downstairs emitters have not been sized to compensate for heat energy migration to other spaces? This isn't considered in any room by room heat loss sizing calculation software that I'm aware of. They all assume closed rooms/zones.
Maybe we should flip our home layouts upside for better thermal comfort, with living spaces upstairs and sleeping rooms downstairs?! 😉

I can’t help but feel a simple solution could be to design houses once again with stairs that are hidden behind a door so the whole of th upstairs can be easily isolated. Failing that, of course, the really low-tech solution of keeping all upstairs doors closed so only the landing overheats.
I’m well aware there are many homes where my generalisations wouldn’t work, of course.
105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs
"Semper in excretia; suus solum profundum variat"
@majordennisbloodnok Aha Bloodnock! I have a sneaky plan, Eccles, put the upstairs in the basement!😉 Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.
Posted by: @toodles@majordennisbloodnok Aha Bloodnock! I have a sneaky plan, Eccles, put the upstairs in the basement!😉 Toodles.
Our last house it was, coolest and most stable temperature summer and winter room in the house, very quiet also. The upstairs was left for guests, way to warm in the summer.
Maxa i32V5 6kW ASHP (heat and cooling)
6.5kW PV
13.5kW GivEnergy AIO Battery.
@johnmo I suppose that gave them a ‘warm welcome’ 😉
There’s something to be said for ‘living’ upstairs in the heated environment and retiring to the lower level to sleep. Anyone carried out an analysis of energy consumption with such an arrangement? Regards, Toodles.
Toodles, he heats his home with cold draughts and cooks his food with magnets.

Posted by: @johnmoPosted by: @majordennisbloodnokcould be to design houses once again
Without an upstairs?
He, he.
You got me rereading what I posted. Fortunately, I did say “once again with…” so there was a qualifying part to the sentence.
Houses certainly often used to hide stairs behind doors, probably so the occupants could heat rooms separately rather than the whole house at a time. I can’t see a good reason for not moving back to that compartmental design.
105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs
"Semper in excretia; suus solum profundum variat"
Posted by: @majordennisbloodnokHouses certainly often used to hide stairs behind doors, probably so the occupants could heat rooms separately rather than the whole house at a time. I can’t see a good reason for not moving back to that compartmental design.
Houses used to have almost no insulation, so compartmentalising made a big difference. For well insulated houses the difference is smaller, because the thermal conductivity between rooms is much greater than the thermal conductivity between the inside and the outside.
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.

Agreed, @jamespa, and understood. However, since an issue related to open plan design has been mentioned I would suggest there is still a place for designing in the option to compartmentalise even if that choice is rarely used and the doors are left open. In fairness there may well be fire safety benefits as well, so I stand by my earlier statement; I can’t see a good argument for avoiding that sort of design.
105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs
"Semper in excretia; suus solum profundum variat"
Posted by: @majordennisbloodnokAgreed, @jamespa, and understood. However, since an issue related to open plan design has been mentioned I would suggest there is still a place for designing in the option to compartmentalise even if that choice is rarely used and the doors are left open. In fairness there may well be fire safety benefits as well, so I stand by my earlier statement; I can’t see a good argument for avoiding that sort of design.
Fair enough and I agree that a closed staircase would reduce hot air rising, although I suspect that convection downstairs together with transmission through an uninsulated ceiling/floor would still convey a lot of heat to the upstairs. Nevertheless it will doubtless have an effect (and you could insulate the floor/ceiling void). Also, as you say, if its fire resistant will also aid with fire compartmentalisation. So from a purely technical function perspective I wouldn't dispute that there is no good reason to avoid this design style.
Of course houses are for living in as well, and many people prefer fairly (or almost completely) open plan. That said, fashion has probably made this more popular than its due and fashions have a habit of reversing!
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
You do realise that by having more doors, it means that there are more doors that your wife can slam in your face. 😋

Posted by: @derek-mYou do realise that by having more doors, it means that there are more doors that your wife can slam in your face. 😋
😁
After more than a quarter of a century married, she’s more than inventive enough already if the situation calls (and I have deserved it on occasion). Another door or two would only serve to reduce the volume; silver linings and all that…
105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs
"Semper in excretia; suus solum profundum variat"
- 21 Forums
- 1,962 Topics
- 42.6 K Posts
- 60 Online
- 2,275 Members
Join Us!
Heat Pump Dramas?
Thinking about installing a heat pump but unsure where to start? Already have one but it’s not performing as expected? Or are you locked in a frustrating dispute with an installer or manufacturer? We’re here to help.
✅ Pre-Installation Planning
✅ Post-Installation Troubleshooting
✅ Performance Optimisation
✅ Complaint Support (Manufacturer & Installer)
Latest Posts
-
RE: What is the best strategy for operating a very oversized heat pump?
It makes sense, although shows a complete lack of thoug...
By JamesPa , 3 minutes ago
-
RE: Setback savings - fact or fiction?
And here in case any one wants it is the code I used in...
By cathodeRay , 6 minutes ago
-
RE: Newbie out of her depth – Samsung AE120RXYDEG 12kW heat pump
No need for apologies, just cautioning about getting to...
By JamesPa , 23 minutes ago
-
RE: Samsung Gen 7 R290 12kW is not behaving how I expected
Definitely its in the 20xx FSVs. Conversely it may be...
By JamesPa , 25 minutes ago
-
RE: Towel rails. An unexpected final hurdle
We have both Normal Rad for heating the room and then a...
By IRMartini , 2 hours ago
-
RE: Heat Pump Sizing & Installation Costs
Perhaps useful to have installed date too? To get conte...
By Tim441 , 4 hours ago
-
RE: SolarPV tables / online calculator
I'd be interested what others find whilst using that we...
By Majordennisbloodnok , 6 hours ago
-
Volumisers in Heat Pump Systems: Does Placement Matter?
The debate over buffer tanks in heat pump systems has b...
By Mars , 7 hours ago
-
RE: F.788 Building circuit pump reports internal fault - Vaillant Arotherm
Guess I have to wait for engineer visit. I really hope ...
By jeegnesh , 18 hours ago
-
RE: Act now to defer the UK road tax increase on EVs
@majordennisbloodnok Damn right sir. my attempt at iron...
By Jancold , 21 hours ago
-
RE: ASHP and heating issues in new build house
That’s good gives you more capacity. It made me think, ...
By Terry1812 , 22 hours ago
-
RE: Seewet manhole cover within r290 exclusion zone
Thanks! I asked Vaillant, and they say I should be fi...
By dbrb2 , 1 day ago
-
Looking for the Grant Aerona 3 setting to turn off completely at 20 OAT
I'm running my Aerona 3 on WC and the 'warm end of that...
By damonc , 1 day ago
-
RE: Do I just go with the lowest quote for my heat pump?
So after signing in Sept in two weeks the install may s...
By Jancold , 1 day ago
-
RE: Victorian Semi Retrofit / Extension ASHP and UFH Advice
When you are renovating is always a good time, as it ma...
By JamesPa , 1 day ago
-
RE: Just one room not reaching desired temperature
Looks like this issue is now resolved. Aira installed a...
By ChandyKris , 1 day ago
-
There have been several people on the OpenEnergyMonitor...
By RobS , 2 days ago
-
RE: Say hello and introduce yourself
Good point @jamespa But that probably strengthens @ch...
By Transparent , 2 days ago
-
RE: Visit a Heat Pump sessions.
Congratulations @toodles, that's a fantastic result. We...
By Old_Scientist , 2 days ago
Latest Topics
-
Heat Pump Sizing & Installation Costs
By Mars 6 hours ago
-
Volumisers in Heat Pump Systems: Does Placement Matter?
By Mars 7 hours ago
-
SolarPV tables / online calculator
By MichelleC 14 hours ago
-
By Toodles 2 days ago