Ducted Heat Pump Recommendation in Waipa (Waikato)

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#3075587 12-May-2023 19:12

Although I don't think you get positive pressure with a heat exchanger.

But if Lossnay has a heat exchanger and a fan to suck air into it and stale air out of it why does it matter if the house is somewhat leaky ?

The more I read / hear the more confused I get.

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rb99

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#3075590 12-May-2023 19:42

rb99:

Although I don't think you get positive pressure with a heat exchanger.

But if Lossnay has a heat exchanger and a fan to suck air into it and stale air out of it why does it matter if the house is somewhat leaky ?

The more I read / hear the more confused I get.

yeah it gets a little confusing.

no you do not get positive pressure with heat exchanger. only balanced ventilation has heat exchanges.

the simple reason that i know of is balanced ventilation (erv/hrv) doesn't do much when there is as much (or more) air flowing in/out of the house through leakage than what the ventilation system blows into the house. if you have the same amount of air blowing through as the erv blows in/out, that means its only going to be 50% effective (assuming erv is 100% efficient, which they are not). for eg think how good would it work if you left a couple of windows open, not very well. your house has the equivalent of a few large windows open all the time.

its simply not worth it for the extra $$$.

by mem i think the nz research shows typical 80's air leakage is between the ventilation rate and double the ventilation rate.

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#3075591 12-May-2023 19:49

tweake:
while its been a while, i have not seen any info to say they are HRV. hold on, i just googled it to check and it looks like HRV cores are a new item. so thanks for the update.

considering how many hack install jobs i've heard of, i don't think the installers would even know, or even care.

Yeah, I doubt my installers knew there was a difference.

I haven’t looked into it, but I don’t think you can just swap out the core to convert ERV to HRV though since the HRV Lossnay models have a drain to get rid of the moisture it removes from the air. The ERV models don’t have a drain.

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#3075595 12-May-2023 20:03

Paul1977:

I haven’t looked into it, but I don’t think you can just swap out the core to convert ERV to HRV though since the HRV Lossnay models have a drain to get rid of the moisture it removes from the air. The ERV models don’t have a drain.

i do not know with lossnay but most others i've seen use one unit and swap the cores over, which is what i would expect from a manufacturing point of view.

timmmay

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#3075597 12-May-2023 20:09

If you have an older house you can get a positive pressure system with a single outlet close the ducted heat pump return. Here's how I use it, all automated with the time based on the season:

Turn on the positive pressure system
If I can be bothered, close the bedroom doors, crack open the bedroom windows (noting that we have return grills in the walls)
Five minutes later, turn on the ducted system in fan mode

This pushes fresh air into the house, and a fraction of the air leaves the house through the cracked windows. In summer it's done during a cool time of the day, maybe 9 - 11am, in winter it's more like 12 - 1pm.

As well as this we run the positive pressure ventilation system at other times without cracking windows open or anything else, such as after dinner when there's cooking smells around.

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#3079375 24-May-2023 14:11

Back again. Am now wondering how people feel about multi-split units ? Seem to be easier and cheaper to imstall and each have their own controls so I presume don't need Airtouch type zone things (I think), but can still be centrally controlled.

Any one with any experiencde of such things ?

I think Timmmay in his blog thing mentioned them but had no personal experience.

Ta.

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#3079376 24-May-2023 14:14

Multi-split units don't need Airtouch. You have one outdoor unit, multiple indoor units each with their own controls / remote. Of course they have to all be on one mode, heat or cool, because there's only one outdoor unit. We didn't put the ducted unit into the kitchen / dining area as it has big windows, so sometimes we're cooling that area while we heat the rest of the house.

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#3079435 24-May-2023 17:00

rb99:
Back again. Am now wondering how people feel about multi-split units ? Seem to be easier and cheaper to imstall and each have their own controls so I presume don't need Airtouch type zone things (I think), but can still be centrally controlled.

Any one with any experiencde of such things ?

I think Timmmay in his blog thing mentioned them but had no personal experience.

Ta.

It’ll perform better for temperature control than a ducted unit serving the whole house. The downside is noise and having a high wall unit in each room.

As mentioned above your whole house will be in heating or cooling but that’s no different to having a single ducted unit serving the whole house.

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#3079450 24-May-2023 18:24

Not too bothered about lots of indoor units, but noise ? little bit, lots ? At the mo we just have a heatpump and single outlet, which is reasonable noise wise. Is multiroom significantly louder, or about the same but not confined too one room ?

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#3079451 24-May-2023 18:38

It's basically the same as having a highwall with individual outdoor units.

The indoor units are pretty much the same as any highwall.

timmmay

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#3079453 24-May-2023 18:48

My experience is newer heat pump outdoor units are louder than older ones, when you're talking about the larger units. I might be wrong, and the specs may disagree with me, but when we changed a 9kw Fujitsu that was 8 years old for a new 10kw Daikin the outdoor unit is a lot louder. Make sure you position the outdoor unit away from living areas and especially bedrooms.

Multiple smaller indoor units shouldn't be loud. My little 3kw Daikin office indoor unit is virtually silent on low, but when you turn the fan up you can hear the air moving and it can get a bit loud, and you do need it up a bit to warm the room initially. The outdoor unit for that is so quiet you can't hear it unless it's dead silent outside and it's working hard.

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#3079477 24-May-2023 21:03

rb99:

Not too bothered about lots of indoor units, but noise ? little bit, lots ? At the mo we just have a heatpump and single outlet, which is reasonable noise wise. Is multiroom significantly louder, or about the same but not confined too one room ?

they are always noisy compared to ducted, for the same level of comfort. thats simply because it has to throw harder to counteract thats its pulling that air back to the start point. you really need that air speed for the efficiency and room converge. with ducted you can plan the airpath across the room, blowing in on one side and sucking it out on the other side. so you can achieve the same at much lower air speeds and less noise.

heat pump in each room is otherwise ok, its just the cost gets right up there. btw i prefer separate units not the single outdoor unit which does them.

however one other factor, cleaning the air. you can fit very good filtration (hepa) on ducted units, very few heat pumps have good filters.

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#3079479 24-May-2023 21:06

timmmay:

My experience is newer heat pump outdoor units are louder than older ones, when you're talking about the larger units. I might be wrong, and the specs may disagree with me, but when we changed a 9kw Fujitsu that was 8 years old for a new 10kw Daikin the outdoor unit is a lot louder. Make sure you position the outdoor unit away from living areas and especially bedrooms.

no problems here. no idea of if thats a brand thing or just that model, or even just that unit.

i was thinking it might be due to the different gas, but i have the R410 and the R32 and theres no real noise difference.

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#3079495 24-May-2023 22:00

tweake:

however one other factor, cleaning the air. you can fit very good filtration (hepa) on ducted units, very few heat pumps have good filters.

I was thinking about that, but haven't done anything about it. Have you done this in the past? What product do you use as a filter? The input of a ducted system can be a 300 - 400m, that'd be a pretty huge filter. I guess you could put it on one of the smaller legs and filter a fraction of the air that goes through.

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#3079498 24-May-2023 22:07

tweake:

no problems here. no idea of if thats a brand thing or just that model, or even just that unit.

i was thinking it might be due to the different gas, but i have the R410 and the R32 and theres no real noise difference.

I was comparing a 12 year old Daikin 7-8kw and 8 year old Fujitsu 9-10kw, with a Daikin ducted 10kw and a Panasonic ducted 10kw. The Panasonic was crazy loud, indoor and out, so probably doesn't count. The Daikin though is louder than expected. The outdoor unit sits just outside our lounge, near where we watch TV, not far from a bedroom. We pretty much never heard the Fujitsu, whereas the Daikin we regularly hear starting up and running over the TV. The ducted unit also runs overnight, my wife finds it starting and stopping fairly loud. The old Fujitsu was often on while we slept, she wasn't so bothered by that.

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