Correctly sizing A2AHP

Spies

I'm trying to get quotes for two rooms to be air conditioned and then to use the units to heat in winter, my living room has a large volume because it has a mezzanine in it, I estimate I would need at least a 5kw wall unit in there, the bedroom is much smaller and a 1.5kw wall unit would likely do the trick in there.

Why is it that every quote I'm getting they simply quote for 2*2.5 or 2*3.5kw units, how can the cooling and heating demand of the bedroom be the same as our large living room?

Bedroom is 26m³ 
Living room works out to roughly 88m³

JSHarris

Not sure if this helps, but I didn't bother with any calculations but just bought a 2.5kW (cooling capacity) Toshiba A2A unit and installed it in our bedroom a few years ago.  The bedroom has a floor area of 21m², but has a high ceiling (around 4m) so the volume is a bit higher.

This is massively too powerful for that room, ridiculously so.  We can leave the bedroom door open in hot weather (like now) and this thing will cool the whole house to around 21°C (if we let it).  We've never used it for heating (we don't have heat in the bedrooms) but I don't doubt it would be far too high a capacity if we did need heat.

I bought a self-install, pre-gassed, kit.  Very easy to install, the hardest part was lifting the external unit high up the wall at the back of the house and getting it on to the wall brackets.  Total cost (in 2019) was about £800.  That includes buying a vacuum pump and set of HVAC gauges.  I only used the pump and gauges once, but it was a lot cheaper to buy them to only use once rather than pay someone to install the unit.

Took me about a day to do the job, working very slowly.  Been working fine for nearly 4 years now. 

Screwdriva

Spies said:

I'm trying to get quotes for two rooms to be air conditioned and then to use the units to heat in winter, my living room has a large volume because it has a mezzanine in it, I estimate I would need at least a 5kw wall unit in there, the bedroom is much smaller and a 1.5kw wall unit would likely do the trick in there.

My neighbour and I are getting quotes for A2A units (also Toshiba). We are going the multi split route which would allow for cooling/ heating capacity to be routed to the indoor units that require it. That said, I share you concern as the large living areas will receive the same blower units as the smaller bedrooms. How effective that will be remains to be determined. 

JSHarris

The Toshiba indoor units have a very wide adjustment range from the remote control I've found.  When set to "eco" mode they are very quiet (fine in our bedroom at night) and don't use much power.  I believe that in a multi split arrangement each indoor unit can be set independently.

Overall I'm impressed with our Toshiba split.  In "hi power" mode it's extremely powerful (and quite noisy) but in normal mode the sound level would be fine in a living room.  In "eco" mode it's whisper quiet, especially if the louvre swing feature is turned off (the motor that swings the louvred hums a bit).

Mikeyboy01443

Every quote for aircon i had was based off room dimensions... even in my conservatory where they say they add a bit for solar effect, it still came out at a 2.5kw unit. I have 2kw in the bedrooms and 3.5kw in the lounge, all work fine apart from the conservatory which i think struggles a bit.  When i asked why they would not put a more powerful unit in there, they said it would end up short cycling a lot, which is bad apparently....
Lessons learned from a multi split system, i would probably have a separate unit for upstairs and downstairs, as when the rest of the family go to bed they liked it on cooling even in the colder months, while i wanted it on heat mode when i was downstairs! So bear situations like that in mind...

Spies

I managed to get them to budge on the spec to 3.5 in the living room and 2.5 in the bedroom on a 5kw external unit but the markup seems insane, I can buy the equipment WITH VAT for £1600, they're wanting to charge me £3500.

QrizB

Spies said:

I managed to get them to budge on the spec to 3.5 in the living room and 2.5 in the bedroom on a 5kw external unit but the markup seems insane, I can buy the equipment WITH VAT for £1600, they're wanting to charge me £3500.

Just for the equipment? Or does that include installation?

Screwdriva

Out of curiosity, what have people paid for a similar multi split A2A HP? (We have 5 indoor rooms to cool)

JSHarris

Spies said:

I managed to get them to budge on the spec to 3.5 in the living room and 2.5 in the bedroom on a 5kw external unit but the markup seems insane, I can buy the equipment WITH VAT for £1600, they're wanting to charge me £3500.

Matches my experience.  I was quoted installed prices that were well over 3 times the price of the kit.  When I installed ours in 2019 I did so illicitly, as a DIY job.  Back then some suppliers were selling pre-gassed, DIY install kits.  Took me about a day, working on my own to install the thing.  Saved about £1k by doing so, even allowing for the cost of the vacuum pump and set of gauges I bought (and only used once).  Frankly I think charging £1k for a day's work is a bit OTT.

Spies

QrizB said:

Spies said:

I managed to get them to budge on the spec to 3.5 in the living room and 2.5 in the bedroom on a 5kw external unit but the markup seems insane, I can buy the equipment WITH VAT for £1600, they're wanting to charge me £3500.

Just for the equipment? Or does that include installation?

3.5k figure they're quoting includes install, some of them are naughtily quoting +VAT too when they're zero rated due to the government right now. 

Mikeyboy01443

Screwdriva said:

Out of curiosity, what have people paid for a similar multi split A2A HP? (We have 5 indoor rooms to cool)

Mine worked out about 1k per room, back in 2020, pretty reasonable i think