New House build - Help needed

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#2490468 24-May-2020 13:29

akmodi:
Or you could simply put in as many single heatpumps....no zones. The advantage being a much higher COP (for heating) and SEER rating ( for cooling) and add TUYA remote control units ( think of them as IOT control remotes in your hand) . They cost about a tenner each .... When programmed.... They can act like one whole unit or separates. Much cheaper and more efficient. These units can be bought for about 1000 each, install is about 750. COP and SEER around 4-5 for each of the units.

Have yet to see a multi zone unit with a high COP or SEER rating.

The added advantage is that if one breaks ... The rest are still functioning 👍

then you have to have the same number of outdoor units outside taking up space and creating more noise. there is more to it that what you have pointed out.

billgates

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#2490475 24-May-2020 13:36

I would not worry about COP ratings. Yearly $$ difference in power use between COP rating of 3 and 5 might be $60 which is insignificant to the cost, design and functionality of a HVAC system. I prefer ducted because it maintains almost even temperature in all rooms and new ducted HVAC systems are not designed to run 24/7 at full blast. Once the desired temperature is reached, its going to use bugger all $$ in power to maintain that temperature. Where ducted really shines is having the ability to use same duct supply runs for ventilation systems so you are not having seperate hi wall heat pumps in rooms as well grills in ceilings for ventilation supply.

Do whatever you want to do man.

Paul1977

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#2490501 24-May-2020 14:37

jonathan18:
If/when I come to build a house, One of the things I would be incredibly unkeen to compromise on is dropping to say a 2.4m stud height, indeed I think I’d elect to sell one of the kids (and build a smaller house) before doing this.

The typical 2.4m stud height is one of the things I dislike about most modern homes - there’s something about a low stud and the typically open plan design that doesn’t work for me. (But, yeah, the 3m my house is built to is probably unnecessary in modern times!)

Fair call. We are having a vaulted ceiling in the main living/dining/kitchen that starts at 2.4m but reaches a little over 3m at the apex. Our main entrance and hallway to the lining area is 2.9m. Media room, bedrooms, bathrooms, and bedroom hallway all at 2.4m.

This gives us a more spacious feeling in the living areas and main entrance, but meant all external framing was 2.4m so not additional cladding, glazing, or insulation costs.

I was just pointing out the benefits of going 2.4m. Cheaper to build, cheaper to heat/cool. And if the OP is on a tight budget a 2.7m stud seems like a luxury. Maybe even compromising at 2.55m would free up enough funds for a better heating system.

I’m happy enough with 2.4m on the bedroom side of the house, but in retrospect wish I’d gone with 2.2m doors on that side if the house instead of the standard 2m. We went over height doors in the living areas, but standard in the rest. At the time it seemed like a big price difference, but in the grand scheme was a pittance.

33coupe

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#2490606 24-May-2020 18:19

Thanks for the posts.

My house is 2.7 in kitchen, dining, in lounge and separate lounge. 2.4 in the rest of the house.

The more I think about it, do think I need ducting. Not sure if zoning is needed, or heat transfer/ventilation, Just need something to take the chill off in winter.

I'll wait to hear back from quotes and ask builder.

Wish me luck telling the other half that any landscaping is on hold lol

Paul1977

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#2490806 24-May-2020 23:14

33coupe: Thanks for the posts.

My house is 2.7 in kitchen, dining, in lounge and separate lounge. 2.4 in the rest of the house.

The more I think about it, do think I need ducting. Not sure if zoning is needed, or heat transfer/ventilation, Just need something to take the chill off in winter.

I'll wait to hear back from quotes and ask builder.

Wish me luck telling the other half that any landscaping is on hold lol

Modern houses are by no means airtight, but they are certainly more airtight than older houses. I believe the minimum recommendation is 1/3 of an air change an hour. With all windows closed most new builds wouldn’t achieve this without mechanical ventilation.

But like everything, it comes with a cost. I think it was about $5k to add a Lossnay to our ducted system, but ours is a larger build so we required are larger system.

It is extremely easy to go down a rabbit of up-speccing, we certainly did and it has added a good chunk to our future mortgage.

Before deciding on the heating, decide on insulation. Better insulation and glazing has a return on investment as well. The better insulated the house the cheaper it is to keep warm/cool. You can bet that whatever the building company recommends will be the minimum they can get away with to be compliant. We went R2.8 in 90mm external walls, R4.0 in 140mm external walls, R6.0 in the ceiling, thermally broken aluminium joinery, and Excel low e argon filled glass. This all added a not small cost to the build, but (we hope) over the years will eventually pay for itself.

We were in the fortunate position of being able to up-spec our insulation & glazing, and also get a ducted heat pump. But if I had to choose, I think I’d go for the glazing and insulation upgrades over the ducted heat pump.

sen8or

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#2491512 26-May-2020 08:29

Small energy efficient panel heaters in the bedrooms will ultimately be cheaper than upgrading to a ducted system, only you can decide where you believe your $ are best spent

Paul1977

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#2491522 26-May-2020 09:34

Back on windows. I think low e glass is probably a better bang for your buck than thermally broken joinery, however it isn't completely straight forward....

It comes down to the size of the window. On a large window you lose far more heat through the glass than the aluminium, but on a smaller window the ratio gets a lot closer.

BUT, if you do spring for thermally broken joinery, you MUST get a thermal spacer in your glazing units. If you have a standard aluminium spacer in the glazing unit it creates a thermal bridge and makes the thermally broken joinery virtually redundant. This was a mistake we almost made when we were thinking of going for Low E Plus (which was a free upgrade at the time from standard glass). But Low E Plus doesn't have a thermal spacer, so would have been a costly mistake when combined with thermally broken joinery.

You can get a thermal spacer in non Low E glazing units if requested, but I have no idea on the price difference.

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nofam

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#2491584 26-May-2020 09:59

Paul1977:

Back on windows. I think low e glass is probably a better bang for your buck than thermally broken joinery, however it isn't completely straight forward....

It comes down to the size of the window. On a large window you lose far more heat through the glass than the aluminium, but on a smaller window the ratio gets a lot closer.

BUT, if you do spring for thermally broken joinery, you MUST get a thermal spacer in your glazing units. If you have a standard aluminium spacer in the glazing unit it creates a thermal bridge and makes the thermally broken joinery virtually redundant. This was a mistake we almost made when we were thinking of going for Low E Plus (which was a free upgrade at the time from standard glass). But Low E Plus doesn't have a thermal spacer, so would have been a costly mistake when combined with thermally broken joinery.

You can get a thermal spacer in non Low E glazing units if requested, but I have no idea on the price difference.

Low e is good, and I'd definitely advise it for north-facing windows, and/or windows that are very large, but the majority of joinery across the house tends toward a lot of smaller windows. And while you do lose the majority of your heat through the glass, even with low-e and argon filled options, you can mitigate it with drapes/blinds. That aside, the key benefit of a thermal break, especially in the colder parts of the country like where OP is building is that it basically eliminates condensation, which is absolutely essential.

In my view, there shouldn't be an option to buy double-glazed aluminium joinery that's NOT thermally broken. I have a mate who built a lovely family home and decided to skimp on the thermal break to save money and he absolutely hates the condensation.

When we built mid-2017, thermally broken joinery added about 30% to the total cost from memory, but it's likely come down.

Froglotion

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#2492300 26-May-2020 21:31

Your mate should fix his ventilation problem. I don't have thermally broken aluminium and get zero condensation.

nofam

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#2492309 26-May-2020 21:42

Froglotion:

Your mate should fix his ventilation problem. I don't have thermally broken aluminium and get zero condensation.

Where do you live though?

33coupe

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#2492315 26-May-2020 21:53

I did ask about thermally broken windows, came back at an estimated $14k.

I also heard back from one company about Ducted heat pump. $13k ducted, $16.5k with lossnay system.

Froglotion

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#2492323 26-May-2020 22:07

nofam:

Froglotion:

Your mate should fix his ventilation problem. I don't have thermally broken aluminium and get zero condensation.

Where do you live though?

CHCH, shouldn't really matter though, even if it wasn't condensating, you're paying more to heat moist air.

Froglotion

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#2492325 26-May-2020 22:11

33coupe: I did ask about thermally broken windows, came back at an estimated $14k.

I also heard back from one company about Ducted heat pump. $13k ducted, $16.5k with lossnay system.

I can't remember if you're CHCH based or not. If you are, speak to these guys, they organised mine.

https://qhs.co.nz/

Jase2985

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#2492438 27-May-2020 07:21

33coupe: I did ask about thermally broken windows, came back at an estimated $14k.

I also heard back from one company about Ducted heat pump. $13k ducted, $16.5k with lossnay system.

id go for the heatpump/lossnay combo over the windows if that's all you could afford.

nofam

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#2492466 27-May-2020 08:20

CHCH, shouldn't really matter though, even if it wasn't condensating, you're paying more to heat moist air.

Yeah, we're in Dunedin. To be fair, at that time he had small children and all the washing that entails so that was probably the cause of the moisture, but there no getting around the fact that aluminium as a fabrication product in joinery has a major downside in being so conductive. So where there's a large heat differential (-3 outside, 19 inside), you're going to get condensation on the frames without thermal mitigation with even the tiniest bit of moisture in the air.

And depending on the joinery construction and to what extent you have eaves to provide some shelter, unbroken joinery can get so cold in winter that it literally radiates cold into your room.

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