Need Advice on Ducted Heat Pump and Ventilation System

Forums › Home Workshop DIY › Need Advice on Ducted Heat Pump and Ventilation System - Which of the Two Options?

btravers33

2 posts

Wannabe Geek

#289519 10-Sep-2021 11:51

Hi All,

I've been a lurker here for a while but haven't found a post that really addresses the specific query I have. I am doing a full house renovation and am taking the opportunity to add a ducted heat pump and ventilation system. We are adding it to the upstairs of our house, which is ~120 sqm. There is plenty of ceiling space and the house will also be well-insulated and double-glazed during the renovation. Here are the options being presented to me currently:

1) 16kw Mitsubishi PEA High Static Ducted Heat Pump System with integrated Lossnay heat recovery and ventilation. WiFi controls included - This option is pretty clear and I have seen plenty of comments on this forum that it is a good system

2) The other provider is recommending a Toshiba Ducted Heatpump system with a Moisture Master Heat Recovery and Ventilation System. This agent claims that this is more efficient in regard to heat loss than the Lossnay system (90% retention vs 70% for the Lossnay). Additionally, they claim that it is more efficient as the systems can be run separately and they can hook it up to the bathroom extractors to recover the heat from those systems as well. - This sounds attractive to me, but I am having trouble finding any reviews or information on this configuration.

I wanted to reach out here to see if anyone had experience with either or both of these systems and could possibly help steer me towards which would be a better option. I am located in Dunedin in a 1947 built house. As mentioned before, we will be undergoing a significant renovation, which will significantly improve the condition and efficiency of the house.

Many thanks in advance for any guidance!

1 | 2

18587 posts

Uber Geek

Trusted

Subscriber

#2775934 10-Sep-2021 12:11

I have a Daikin ducted heat pump with an Airtouch controller. My first recommendation is zoning is ESSENTIAL otherwise you will find some rooms will be super hot and others ok. Rooms that get a lot of sun north facing are problematic. I had an older ducted heat pump that I had removed because it wasn't zoned, one north facing bedroom got SUPER hot but was small. So the manual damper put only a little heat in because it's small, but if you want to cool it down quick you need the damper wide open, which meant going up into the roof. Not practical.

A key consideration is minimum heat output. With Airtouch system if you only need a bit of heat under the minimum the rest goes to the spill zone, which in our case is the lounge. So 1kw goes into the bedrooms at night, 4kw goes into the lounge even though that zone is turned off. It can overheat quite easily. Our old but well insulated house does fine with 10.5kw, it is probably larger than it needs to be. Dakin are fine, our outdoor unit is faulty it makes some weird loud noises but they're replacing it.

Make sure you have a specialist firm do it. I had a ventilation firm do the first ducted heat pump and they did a rubbish job in many ways, even though they'd done plenty. So experience doesn't always count if their experience is doing it wrong.

If I was doing it again I would consider just doing high walls. Simpler. I might still end up ducted, but I'd consider high walls.

Lenovo

Affiliate link

Affiliate link: Find your next Lenovo laptop, desktop, workstation or tablet now.

blackjack17

1507 posts

Uber Geek

#2775998 10-Sep-2021 12:50

We have a Fujitsu 12 Kw ducted in a 160m2 house (2 storey) that heats the place brilliantly. We don't have it zoned and all of the rooms just even out.

It is in a 1920 house in Auckland all single glazed wooden joinery with plenty of gaps we have ceiling insulation and parts of the floor. I think a big part of what makes it work is up stairs (which makes up 2/3s of the floor area has a 3.2m stud and all of the heating vents and returns are in the floor so we don't get any stratification. The house it self is also naturally warm being in a nice little microclimate.

We love the ducted system and much prefer it over a single wall mount that we had in our last 1950s (much better insulated 2.4 ceiling stud) house that only made it feel not cold. We ended up getting a fireplace there that made the place toasty.

The ducted system has no breeze, warms the house in 10 minutes and heats evenly.

Electric kiwi signup credit Sharesies credit

timmmay

18587 posts

Uber Geek

Trusted

Subscriber

#2776045 10-Sep-2021 14:00

I suspect whether you need zoning depends on your location and house. It's essential for us because one north facing bedroom can be 28 degrees even with the curtains closed while the lounge and other bedrooms are 20 degrees. That's difficult to address without zoning.

Our ducted system has a breeze, which doesn't stop even when the house is up to heat, though we're hopefully getting that turned off soon. The large lounge can go from 18 degrees to 23 degrees in about an hour. They're designed more to stay on all the time rather than go on and off, we just change the thermostat down if we're not here.

blackjack17

1507 posts

Uber Geek

#2776060 10-Sep-2021 14:33

I guess out comes vary quite a bit as we only turn ours on when we need heat, then crank it up at 9 for free hour of power and then off at 10.

Sometimes we turn it on for half an hour at six if the morning is esp cold.

Electric kiwi signup credit Sharesies credit

timmmay

18587 posts

Uber Geek

Trusted

Subscriber

#2776130 10-Sep-2021 16:20

I suspect the Dunedin climate is more like Wellington than sunny Auckland. We leave out ducted heat pump on 24/7, works great. If the north facing rooms get a lot warmer than others down in Dunedin seriously consider zoning. Happy to provide more info, and I'll write up my experiences with ducted heat pumps when I get to it.

decibel

204 posts

Master Geek

#2776228 10-Sep-2021 20:25

I have no experience with those brands mentioned by btravers but like others above, installing a ducted system is a MAJOR PLUS.

timmmay

18587 posts

Uber Geek

Trusted

Subscriber

#2776232 10-Sep-2021 20:39

Don't buy a Panasonic ducted system. Or any Panasonic heat pump. Really, really loud. Like a truck idling outside. The Daikin is a whisper by comparison.

I have a feeling that heat pumps based on the newer R32 refrigerant are louder than older ones. Both my 8 - 10 year old units were near silent in operation. The new Panasonic R32 I returned was super, super loud. The new Daikin R32 is significantly louder than either of the old ones. The old ones you could only tell the outdoor unit was going if you stood within a meter of it. The Panasonic you could tell from anywhere on the property or one neighbour over. The Dakin you can hear from inside or from 3-5 meters away but it's not so bad.

Danite

29 posts

Geek

#2776262 10-Sep-2021 21:58

I have 2x Mitzi ducted, one living area, one bedrooms. When it was installed I briefly looked into Lossnay, it was usable with 2x systems but lost some features, I was also on a budget and preferred the two systems.

What I was getting to was that that 70% efficiency on the Lossnay seems BS, did the second installer claim that? From what I remember when I was reading it was around that same 90% number I would double check that.

timmmay

18587 posts

Uber Geek

Trusted

Subscriber

#2776264 10-Sep-2021 22:05

I didn't get an integrated ventilation system. I have a standard positive pressure ventilation system, the input goes through a hepa / charcoal filter in a filter box. That outputs to beside the ducted system return vent. The ventilation system plus into a Kasa Wifi timer. I have ventilation running when I need it - middle of the day in winter and a half hour after dinner, mornings and evenings in summer. Condensation isn't an issue since we have ventilation, heating, double glazing. Before I did all this we had windows so wet they would saturate a large towel if it was even fairly cold outside, now we get a light mist on maybe the 10 coldest days of the year. Humidity hovers around 50%.

btravers33

2 posts

Wannabe Geek

#2776582 11-Sep-2021 21:28

Thank you so much everyone for your responses. This is great information and very helpful. Much appreciated! I’ll take a look at the Daikin system and see what the agents are offering for that down here.

timmmay

18587 posts

Uber Geek

Trusted

Subscriber

#2776652 12-Sep-2021 06:34

Daikin apparently offer a zoning system and one that has temperature sensors in each room. I asked an air conditioning firm about it they didn't know anything, so they called Daikin. I'm told Daikin told them that it was ok, not great, from memory it could only keep a room within 4 degrees of the setpoint - so if you set to 22 it could be anywhere between 20 and 24 - a fairly large range. You'd want to check this because it sounds terrible. I would generally have preferred to have a system with all components by the OEM, but I ended up with the Airtouch controller system and a Daikin heat pump.

Airtouch is pretty good. You get a nice 5" screen / app to set the mode and target temperatures for each room. It has a box in the ceiling that controls everything, along with electric dampers on the ducts to close / open / part open each room in response to temperature. It's got an ok timer, but you can only choose temperature, not mode. It integrates with IFTTT but again only in very simplistic ways. It has a good app, works well. It has a local network interface, and there a Python API I haven't tried, but I'm thinking if I want a proper timer I'm going to have to write some Python. The software release a few days ago pushed out something called Zimi which is meant to be another home automation platform but it doesn't work yet.

Again, if you go ducted with sensors in each room a key need is a low output to the heat pump. If you're trying to keep two bedrooms at 20 degrees and it's only taking 1kw, and you have a minimum output of 5kw, that heat has to go somewhere.

timmmay

18587 posts

Uber Geek

Trusted

Subscriber

#2777075 12-Sep-2021 17:10

If you want a really effective system you'll want your outlets in the ceiling and your return vents at floor level. That way the warm air is drawn down and across rather than just pushing across the ceiling and not heating the floor. I'm told a 400mm return is pretty good, or multiple smaller returns, so good to do during a renovation if you have space. A central cupboard like a linen cupboard in a hallway can be used as a return sometimes.

These square four way ones are much more effective than the basic round ones. You can point them in various directions which is especially important if you have ceiling level output and input, but is good in either case. It means you can have the hot air going towards the floor. In summer you can tweak them a bit differently if you need to, as cool air falls.

Handle9

7815 posts

Uber Geek

Trusted

Lifetime subscriber

#2777116 12-Sep-2021 18:31

timmmay:

I suspect whether you need zoning depends on your location and house. It's essential for us because one north facing bedroom can be 28 degrees even with the curtains closed while the lounge and other bedrooms are 20 degrees. That's difficult to address without zoning.

Our ducted system has a breeze, which doesn't stop even when the house is up to heat, though we're hopefully getting that turned off soon. The large lounge can go from 18 degrees to 23 degrees in about an hour. They're designed more to stay on all the time rather than go on and off, we just change the thermostat down if we're not here.

Ducted systems, especially zoned systems, need to be designed not just installed. If there aren't heat load and airflow calcs you're just hoping it will work.

Handle9

7815 posts

Uber Geek

Trusted

Lifetime subscriber

#2777118 12-Sep-2021 18:33

timmmay:

Daikin apparently offer a zoning system and one that has temperature sensors in each room. I asked an air conditioning firm about it they didn't know anything, so they called Daikin. I'm told Daikin told them that it was ok, not great, from memory it could only keep a room within 4 degrees of the setpoint - so if you set to 22 it could be anywhere between 20 and 24 - a fairly large range. You'd want to check this because it sounds terrible. I would generally have preferred to have a system with all components by the OEM, but I ended up with the Airtouch controller system and a Daikin heat pump.

+/- 2 degrees of setpoint is generally imperceptible to occupants providing the system is mixing correctly.

timmmay

18587 posts

Uber Geek

Trusted

Subscriber

#2777136 12-Sep-2021 20:28

Agree that design would be useful. I've had two ducted systems install, first not zoned, second zoned. Neither company appeared to do any calculations other than floor area measurement. The non-zoned ones probably need a lot of design work, particularly if they have rooms with sun exposure. The zoned ones with automatic adjustments would seem to be more adaptable and probably need less design.

We can tell the difference of about a degree. It starts getting a little cooler, then the system kicks in and brings it up a notch. If it goes up two degrees say from 24 to 26 it's quite significant.

1 | 2