Best Ducted Heatpump

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Jase2985

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#2258344 14-Jun-2019 17:07

mattwnz:

Jase2985:

floydie:

Oh and don't believe the haters saying that ducted is less efficient.

you cant say that, because it IS less efficient, it looses heat though the ducts where as a floor, highwall or cassette one doesnt. there may not be much in it but you cant argue against physics.

thats not saying dont get one but just be aware of heating and cooling losses through the ducts. so maybe spend a little bit extra on getting more insulated ducting.

How much heat / cooling is actually lost though, especially when compared to a multi indoor unit piped around to the same areas? Ducted only works if you also have a good amount of roof space for the wide insulated pipes, so they aren't suitable for all, including low pitched or skillion.

you dont pipe multis anywhere, you have a unit in each room you wanted heated or cooled.

its also a lot easier to insulate a 25mm pipe vs a 150-300mm one if you are talking about the refrigerant pipe.

mattwnz

20141 posts

Uber Geek

#2258390 14-Jun-2019 18:35

Jase2985:

you dont pipe multis anywhere, you have a unit in each room you wanted heated or cooled.

its also a lot easier to insulate a 25mm pipe vs a 150-300mm one if you are talking about the refrigerant pipe.

That is what I meant. We have 3 internal units in different rooms, each piped back (refrigerant pipe) to a central outdoor unit, and it seems to work well. The ducted system wasn't an option due to a lack of roofspace. I believe each can also be setup with a wifi module. Although we only have one wifi module currently setup with a separate large single heatpump. They are all mitsubishi, and the wifi module seems to work ok, although occasionally the ipad struggles to find a connection to the server. It does also have alexa support for voice control of the heating and cooling. Also becuase teh inoor units are silver and simple looking, they actually look good compared to many heatpump internal units. I even prefer the look to vents in the ceiling or walls.

floydie

474 posts

Ultimate Geek

#2258612 15-Jun-2019 08:28

The biggest plus for ducted is it puts air IN the bedrooms...
Its all good to say have a wall unit in the hall but then that all goes tits up when you close the bedroom doors. Having a wall unit pumping away at 28 degrees in the hall just to get heat into the rooms isn't efficient.
With ducted even with doors closed the rooms get heated. In fact the rooms actually get warmer with the doors closed because the return air makes it way under the doors so the room fills with warm air and the cool air at floor level gets sucked out under the door.
And to have a cool breeze in your room on those stinking hot summer nights is bliss.
YOU can overthink controls sure its nice to have the alexa controlled WiFi dongle that makes your coffee but honestly we touch our controller maybe twice a day as we walk past it. Not exactly taxing.

Kickinbac

427 posts

Ultimate Geek

#2258625 15-Jun-2019 09:50

Paul1977:
mattwnz:

bfginger: Personally I would prefer to put the money of a ducted system towards making the build more along passivehouse lines so it doesn't need as much heating and cooling.

Somewhat difficult though in an urban environment, where sun maybe blocked by neighbours. Especially low angled winter sun, which you want to heat a thermal mass like a concrete slab.

I've done a little reading over the past few days, and what you are talking about is passive solar heating which is just one aspect. I think the main aspects of a passive house are the insulation and air tightness so once it's at the desired temperature it's easy and cheap to keep it there.

I'm certainly going to get pricing for upgrading of insulation and glazing and adding fresh air with heat recovery to the mix. I think going the route of a full blown certificated passive house would be extremely expensive in NZ, but following some of the principals might be manageable - if it makes financial sense.

The problem is I just don't know how to work out if the increased build costs would ever be recouped in power savings.

If it adds $100 per month to the mortgage payments, will it be saving $100 per month in power? If not then I probably can't afford it.

For a ducted system, all the air distribution is outside the insulated envelope of the building (in most situations). If there is no care for efficiency and energy cost they can be great. From my experience ( I’m a HVAC engineer) most ducted systems use the cheapest insulated flexible duct (R0.5) which just leaks energy.

Aredwood

3885 posts

Uber Geek

#2258632 15-Jun-2019 10:36

floydie: The biggest plus for ducted is it puts air IN the bedrooms...
Its all good to say have a wall unit in the hall but then that all goes tits up when you close the bedroom doors. Having a wall unit pumping away at 28 degrees in the hall just to get heat into the rooms isn't efficient.
With ducted even with doors closed the rooms get heated. In fact the rooms actually get warmer with the doors closed because the return air makes it way under the doors so the room fills with warm air and the cool air at floor level gets sucked out under the door.
And to have a cool breeze in your room on those stinking hot summer nights is bliss.
YOU can overthink controls sure its nice to have the alexa controlled WiFi dongle that makes your coffee but honestly we touch our controller maybe twice a day as we walk past it. Not exactly taxing.

Why are you comparing ducted to a single high wall unit in a hallway? Compare ducted to having a small high wall unit in each bedroom.

Smaller units have better efficiency than large units. Even comparing small high walls to large high walls. And that is before you have to make allowances for ducting losses. Zone control is extremely easy when each room has it's own unit. And no problems with coping with different cooling or heating requirements for different rooms.

gb67

44 posts

Geek

#2258923 15-Jun-2019 22:05

+1 for Daiken. Used The Heat Pump Co (Part of Christchurch Electrical) very pleased with results.

dusty42

117 posts

Master Geek

#2261138 19-Jun-2019 21:29

Kickinbac:For a ducted system, all the air distribution is outside the insulated envelope of the building (in most situations). If there is no care for efficiency and energy cost they can be great. From my experience ( I’m a HVAC engineer) most ducted systems use the cheapest insulated flexible duct (R0.5) which just leaks energy.

Can you share a bit more about ducting? What's the performance difference between cheap and expensive ducting? Approx price per metre?

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Kickinbac

427 posts

Ultimate Geek

#2261157 19-Jun-2019 22:13

dusty42:
Kickinbac:For a ducted system, all the air distribution is outside the insulated envelope of the building (in most situations). If there is no care for efficiency and energy cost they can be great. From my experience ( I’m a HVAC engineer) most ducted systems use the cheapest insulated flexible duct (R0.5) which just leaks energy.

Can you share a bit more about ducting? What's the performance difference between cheap and expensive ducting? Approx price per metre?

Simx do durable and well insulated in various insulation thicknesses and a good example of durable ductwork. R1.5 is not commonly sold.

http://simx.co.nz/product-groups/duct-and-grilles/ducting/unilok-fr1-flexible-ducting

Would have to do a bit more research for technical details. A good insulated ceiling in R4.0 and above so compare that with ductwork insulation.

I’ll look at a price comparison tomorrow and post.

Another issue to consider is leakage. Ducts come apart and leak into the ceiling wasting heated or cooled air.

JayADee

2148 posts

Uber Geek

#2261205 20-Jun-2019 08:02

We had a Mitsubishi split unit installed in 2012 and been perfectly happy with it. The outdoor unit is outside the kitchen next to the windows near the dining table and we never hear it. Next time I would probably have that outdoor split unit run to the kitchen and lounge and put a separate outdoor unit out the back to the man cave because it's furthest away.

Kickinbac

427 posts

Ultimate Geek

#2261208 20-Jun-2019 08:14

Kickinbac:
dusty42:

Kickinbac:For a ducted system, all the air distribution is outside the insulated envelope of the building (in most situations). If there is no care for efficiency and energy cost they can be great. From my experience ( I’m a HVAC engineer) most ducted systems use the cheapest insulated flexible duct (R0.5) which just leaks energy.

Can you share a bit more about ducting? What's the performance difference between cheap and expensive ducting? Approx price per metre?

Simx do durable and well insulated in various insulation thicknesses and a good example of durable ductwork. R1.5 is not commonly sold.

http://simx.co.nz/product-groups/duct-and-grilles/ducting/unilok-fr1-flexible-ducting

Would have to do a bit more research for technical details. A good insulated ceiling in R4.0 and above so compare that with ductwork insulation.

I’ll look at a price comparison tomorrow and post.

Another issue to consider is leakage. Ducts come apart and leak into the ceiling wasting heated or cooled air.

Here is an example of price, not including freight, installation etc. This is just one supplier, one product, one size from list price.

There are several other suppliers out there. R1.5 duct is rare, not many do it and can be slow to get.

200 diameter

Insulated R0.6 $40.00 incl GST for 3 metre length

Insulated R1.0 $53.60 incl GST for 3 metre length

Insulated R1.5 $71.50 incl GST for 3 metre length

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