Aircon engineers / Best installers - designers for ducted in CHCH

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mrhaboobi

195 posts

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#323913 2-Feb-2026 13:46

Hi All.

13 years ago we had a ducted system installed. we had an installer who seemed to know what they were doing.. The unit has continued to work well. however we are moving to a different property and I'm now looking for recommendations on educated installed of whole home ducted systems. Have had some quotes from the bigger players and feel like they might be under sizing the units.. What is most important to me ( other than the system working of course ) is noise. I'm a light sleeper i need to main roof unit to be in a location not near the master bedroom, and vent noise to be quiet ( no airflow noise, so vents correctly sized ).

Can anyone suggest experienced installers and designers that will provide the right product installed well..

Side question. One or two people suggested GREE units .. I'm a bit uncomfortable with that just because its less well known here, ( I'm looking at the Daikins and Mitsi units mainly ).. Future desires to expand to a ERV/HRV ( not the HRV brand ) .. but this is secondary due to costs, but keen to make sure im not limiting myself with integrations etc.

Ok very keen to hear chch based recommendations for ducted please.

Thank you

Obraik

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#3458074 2-Feb-2026 14:02

What makes you think they're undersizing the unit?

You also want to make sure that you're not oversizing the unit as short-cycling is bad for efficiency

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mrhaboobi

195 posts

Master Geek
+1 received by user: 9

#3458076 2-Feb-2026 14:09

One person who did some calcs for me ( they don't install any more ) suggested the calculated needed were Cool 11.5kw , Heat 11KW and suggested 14 Heat / 12 Cool to make sure we were not under sizing on the cooling. The companies i have spoken to quoted 12.5 Heat / 10 cool. They all seem to use the same software, they all seem to exclude some rooms ( which will we open and likely consuming some of the cooling / heating ). so worried that they are opting to go for less rather than the go for more. This of course is my un educated assumption..

mrhaboobi

195 posts

Master Geek
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#3458078 2-Feb-2026 14:26

Obraik:

What makes you think they're undersizing the unit?

You also want to make sure that you're not oversizing the unit as short-cycling is bad for efficiency

sorry see my reply below, forgot to "quote"

Obraik

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#3458085 2-Feb-2026 15:15

Have you gone back and told those companies that the rooms they're excluding will be open? I would assume their tool is likely adding in some buffer of its own based on the measurements and performance of the suggested heat pumps. I get you have a friend who used to be in the business, but if you've got multiple other sources suggesting something different to this friend, your friend might be using outdated calculations for todays options and conditions.

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mrhaboobi

195 posts

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#3458092 2-Feb-2026 15:49

Obraik:

Have you gone back and told those companies that the rooms they're excluding will be open? I would assume their tool is likely adding in some buffer of its own based on the measurements and performance of the suggested heat pumps. I get you have a friend who used to be in the business, but if you've got multiple other sources suggesting something different to this friend, your friend might be using outdated calculations for todays options and conditions.

Yup that's fair, still to have more discussions with the companies, but equally if they dont ask if a room is in use and they are doing the design then are they really doing a design and do that have experience :) not trying to be a dick but kinda expect a well experience company would look at a floor plan, ask some questions or point out that this room would or wouldn't be covered ( just like some do with making sure you know about trimming doors or returns in each rooms etc. ). so if i have to ask them everything and point out small things like that then already its a red flag :) ( maybe i expect too much, im reading the other thread on a persons experience and i dont want to have to go through their pain )

boosacnoodle

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#3458149 2-Feb-2026 22:52

Had my install done by ATL. Mitsubishi ducted AC with Lossnay. They had to come back a few times to fix various things, which they mostly sorted. Ended up getting things permanently fixed with Beattie Air at my own cost. I did get a quote from Beattie Air originally and it was substantially more than ATL - even with getting the subsequent issues sorted.

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sen8or

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#3458168 3-Feb-2026 08:00

Both my wife and son work for an aircon company, they rank Mitsubishi highly for quality of units, well worth investigating.

When we did our house install a few years ago, we opted for 2 smaller units giving us 6 outlets in total, both 8kw Hitachi units, one for the living areas (2 outlets in open plan kitchen/living/dining and 1 outlet in media room), one for the bedrooms (1 outlet in each of 3 bedrooms), this works well for us as bedroom temperature is lower than living areas. I realise that you can have zones with many systems so isn't really necessary to have 2 completely separate units, but it works for us with neither unit having to work too hard.

tweake

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#3458476 3-Feb-2026 18:05

mrhaboobi:

One person who did some calcs for me ( they don't install any more ) suggested the calculated needed were Cool 11.5kw , Heat 11KW and suggested 14 Heat / 12 Cool to make sure we were not under sizing on the cooling. The companies i have spoken to quoted 12.5 Heat / 10 cool. They all seem to use the same software, they all seem to exclude some rooms ( which will we open and likely consuming some of the cooling / heating ). so worried that they are opting to go for less rather than the go for more. This of course is my un educated assumption..

can you post a floor plan?

common thing is to oversize, simply to upsell. pretty rare for them to under size. however they may be basing it on heating rather than cooling as that tends to be nz culture.

excluding rooms, it depends on if the rooms put any load on the house. anything with an outside wall needs to be taken into account. rooms with only internal walls don't need anything load wise. hence post a floor plan.

it also depends on the type of house and how you will run the house. most houses here are badly insulated with bad air leakage, so most don't run heat pumps properly and usually oversize them to suit that style of use.

timmmay

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#3458695 4-Feb-2026 14:05

Ducted systems are sometimes better undersized, otherwise they stop start stop start rather than running continuously at lower power, which I hear is meant to be better for longevity. We very rarely if ever end up in the situation where we can't get to target temp, as for example in winter the system is turned down rather than off on really cold days, and generally we turn it on a few hours before we need a room up to full temperature. Home Assistant integrations and automations are useful for that.

With Daikin you can have it turn the air circulation off when heating or cooling achieves its target, which I find important here.

You may find my ducted heat pump guide useful.

mrhaboobi

195 posts

Master Geek
+1 received by user: 9

#3458697 4-Feb-2026 14:07

timmmay:

Ducted systems are sometimes better undersized, otherwise they stop start stop start rather than running continuously at lower power, which I hear is meant to be better for longevity. We very rarely if ever end up in the situation where we can't get to target temp, as for example in winter the system is turned down rather than off on really cold days, and generally we turn it on a few hours before we need a room up to full temperature. Home Assistant integrations and automations are useful for that.

With Daikin you can have it turn the air circulation off when heating or cooling achieves its target, which I find important here.

You may find my ducted heat pump guide useful.

Sure Can

tweake

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#3459118 5-Feb-2026 17:30

mrhaboobi:

Sure Can

11kw heating is probably about right (quick and dirty calc). however cooling is much harder to calc. what compounds it is most heat pumps have less cooling than heating. i would be inclined to make sure its designed to be cool. i don't know what orientation the house is, but keeping window size down helps (and helps the wallet) and having shade features on the sunny side. bedroom 2 and 3, the windows could be reduced in size. master is fine. the hallway doesn't need windows and the living room windows could do with downsizing. especially in a small house like this its difficult to have useable space if there is a window in the way. does the dining room need two doors? also check the height of the windows. you don't need floor to ceiling windows and they takes up useable space.

also two doors in a bathroom to me is eck. but nice detail having a wc across from the kids bedrooms.

only room not needing heat/cool is the laundry. i would put an hvac exhaust in there to help with keeping it dry, which in turn will drag in heat/cool from the rest of the house.

then there is shading over the windows/walls. eves or awnings etc. keeping the summer sun off helps a lot and keeping the rain off helps with durability.

hope that helps.

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timmmay

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#3459188 5-Feb-2026 21:23

My experience with one house is cooling needs in NZ are usually significantly less than heating needs. My heat pump in winter has to increase the temperature from outside by up to 20 degrees, from maybe zero at times to about 20 degrees. In summer it has to drop 3-5 degrees off the indoor temperature. Providing shade for the house reduces cooling needs significantly.