Healthy Homes Heating Tool Question

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mrhaboobi

165 posts

Master Geek

#274498 25-Aug-2020 16:09

So wondering if anyone has had a result like this

You need 6.3kW of heating capacity to heat your living room

This is the minimum required heating capacity you need to meet the healthy homes standards, based on the information you supplied. It takes into account your local climate and the design and construction of your home. The tool makes some assumptions to keep things simple.

Your heaters need to provide this heating capacity with an outdoor temperature of -4°C

Heat pump installers need to know the outdoor temperature to work to. This is because the heating capacity of a heat pump reduces with colder outdoor temperatures. If you live somewhere cold, you may need a particular model of heat pump to give enough heating capacity.

6.3KW @ -4 degree means you need a heat pump of about 8-9 KW to achieve that . This is for a small house in chch, 47 sqm living ( open plan ).

most companies rate their heat pumps running at 7 degrees.

Anyone else in this situation? a 9KW unit is teh largest that some manufactures make. Let alone complete overkill for a room that size.!

Is it correct that the capacity needs to be rated at -4 or that they have assumed an external temperature of -4 on average and therefore need 6.3 KW?

timmmay

20578 posts

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Lifetime subscriber

#2549579 25-Aug-2020 16:20

Where do you live, what kind of insulation do you have in the walls ceilings floors, and windows, do you have downlights and if so are they covered with insulation?

9kw seems huge for that small a room. 9 kW heats our lounge and bedrooms in our old but well insulated house.

mrhaboobi

165 posts

Master Geek

#2549587 25-Aug-2020 16:26

Its a new build in chch.

i know 9kw sounds huge, but if you are looking at rated performance at -4 degrees then thats what you need to achieve a 6.3K output. And that is what im questioning... because thats what the healthy homes site is proposing

timmmay

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#2549593 25-Aug-2020 16:29

Larger heat pumps don't cost that much more than small ones, so you might as well just get a big one. For a new build I would go ducted unless it is a really simple open space.

mrhaboobi

165 posts

Master Geek

#2549598 25-Aug-2020 16:31

Well by new build its 1 year old with a 6kw unit installed already, which based on the calcs doesn't cut the mustard and so i just wanted to confirm if my understanding of the -4 was correct.

I cant fit the larger unit on the wall space. :)

kotuku4

483 posts

Ultimate Geek

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#2549599 25-Aug-2020 16:35

The difference between theory and practice.

We can keep our small three bedroom house at an acceptable temperature using one 6kw heat pump in the open plan living area.

Location Blenheim, 120m2 built 1996, walls insulated, additional ceiling insulation added, retro fit double glazed. We try to keep the house warm and dry.

Not as cold as CHCH, not sure about average -4, Perhaps someone wants to sell lots of heat pumps?

You would be looking at ducted HVAC with heat pump, or multiple heat pumps to achieve the design standard.

SirHumphreyAppleby

2844 posts

Uber Geek

#2549612 25-Aug-2020 17:42

mrhaboobi:

So wondering if anyone has had a result like this

You need 6.3kW of heating capacity to heat your living room

The calculator is nonsense and should not be relied upon by anyone who isn't using it to sell heat pumps.

It claims we would need 2.1kW to heat our living room if we had no windows, and R3.2 insulation in the floor, ceiling and walls. We have 30-plus year old Insulfluff for roof insulation, single glazed windows and no wall insulation, and we can comfortably heat our living area, left open to the rest of the house (around 220m^2), with a single 1.8kW micathermic heater.

mrhaboobi

165 posts

Master Geek

#2549613 25-Aug-2020 17:50

Don't disagree :) BUT.. its a legislation so its somewhat important right now as it stands.

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SirHumphreyAppleby

2844 posts

Uber Geek

#2549615 25-Aug-2020 17:58

mrhaboobi:

Don't disagree :) BUT.. its a legislation so its somewhat important right now as it stands.

Actually, it's a regulation.

If anyone wants to check the numbers, here's the formula... http://www.legislation.govt.nz/regulation/public/2019/0088/latest/whole.html#LMS160629#LMS160629