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Topic # 193422 10-Mar-2016 15:21
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Any one had one of these systems installed recently? which kind did you go with and how much did you pay? Any recommended installers??


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  Reply # 1510684 10-Mar-2016 16:41
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did you have a look for threads? there are a couple of recent (last 6 months) about ducted heat pumps which have good info in them


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  Reply # 1510994 11-Mar-2016 00:03
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Yep, as Jase2895 has pointed out, there's been quite a lot on ducted heatpumps, so you're best to read through those and then perhaps ask specific questions once you've done that. 

 

Took only a few seconds to find https://www.google.co.nz/webhp?sourceid=chrome-instant&ion=1&espv=2&es_th=1&ie=UTF-8#q=ducted%20heatpump%20site%3Ageekzone.co.nz

 

The first thread that shows there is one that I started; there's also one that was only in the past few weeks.

 

Happy to answer any questions, as I have learned that it's far from straight-forward, and is way more complex than putting in standard units (or even split units). Some will argue, as they do on these threads, that multiple standard or split units may offer a better solution than a ducted system (in particular the ability to control each room individually). Personally, I'm still glad we went for a ducted system as I like the ease of being able to heat the whole house (or half the house - we chose two zones, but it can be done down to each room, just needing dampers installed) with the press of one button, and not having to have those fairly large and obvious units on the wall (or ground). Just that I know what the traps are next time I do it!

 

I know there have also been threads discussing gas central heating, and some here are big fans of it; personally, I wanted the remote control options provided by heatpumps (ie, wifi), and wanted to avoid being reliant on burning a fossil fuel.  

 

 


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  Reply # 1511025 11-Mar-2016 06:33
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I went with EES and a panasonic ducted heat pump with the IntesisHome wifi module.  4 bedrooms + large open plan living space with a total of 8 outlets came to about $9,500 just after xmas of 2014.

 

I use it mostly for cooling, my house is pretty warm in winter but unbearably hot in summer


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  Reply # 1511128 11-Mar-2016 10:35
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I have some interesting experience I will share, a bit of a long story though… So in short I would say if you can get away without cooling and have mains gas avail to your property then a ducted gas system wins hands down.

 

 

 

I didn’t see discharge temps mentioned in the other threads which I think is a big negative for ducted heat pump systems.  

 

I’m in AKL by the way if that makes a difference.

 

When we moved into my current house it already had a 5.5Kw Rinnai flued gas heater in one living room and nothing in the other. I didn’t research it much at that time but had a friend working as a heat pump installer so I got him to install a Mitsubishi 7.5Kw heat pump in the other living area.  It heated the room ok but never really liked it, it took forever to warm up and it was noisy and windy.  Last winter we started a big renovation and took down the wall that separated these two rooms so I had the perfect opportunity to test them back to back in the same room.  I ran the gas heater only for a few days then the heat pump only for a few days then swapped back and forth a few times and recorded energy use from the meters.  There of corse will small errors since I couldn’t isolate all other energy use – toaster etc, but I thought by averaging over a week or so I had pretty good repeatable numbers.

 

To keep the room at 20°C the gas heater was burning on average about 4.0Kwh whilst the heat pump about 1.8Kwh. So it seemed to start with my heat pump was never as efficient as quoted.  i.e. it was using 1.8Kwh to produce something around 4Kwh?

 

If you take into consideration my gas is 1/3 the cost of my electricity then even on the best day you could say the gas heater was probably always cheaper to run.

 

 

 

But the big difference was the comfort level and this I believe is due to the big difference in discharge temp between the two technologies. The air coming out of the heat pump is only about 35-38°C compared to the gas at 85°C.  That means to warm the same space the heat pump needs to push a whole lot more air through which makes it more drafty and noisy.  I think because the delta T is lower you don’t have as much natural convection so there were parts of the room that never got as warm.  It also means it takes longer before you feel the warmth.  i.e when you had 85°C blowing into a 15°C room you felt it straight away.  We would need the heat pump to turn on an hour before we woke up whereas the gas only needed 15mins.

 

I believe things would be even worse with a ducted system since I have heard you lose about 1°C of discharge temp per meter of duct in an underfloor system so that means your discharge temp might only be ~30°C.

 

 

 

So even though I was initially a believer in heat pumps and the ability to cool would have been nice (for at least a couple of days of the year anyway) when it came time for a ducted system I went for gas. There are also “unlimited” gas plans now for $129 which make it fairly attractive if you have gas hot water and/or cooking aswell…

 

Since it’s just been installed and it’s summer I cant really tell you how good it heats but I can tell you that it is very quiet even on full. I don’t think you would be able to sleep with a ducted heat pump on but this one I cant even hear it start up.

 

 

 

I got quotes from the 3 big brands, Bonaire, Breamir and Bravis, for a 30Kw system they varied quite a bit - from $8900 to $14K. I also got a quote from EES for a ducted heat pump system (2 x 15Kw units) and that was $13.9K.




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  Reply # 1511145 11-Mar-2016 10:42
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awesome, thanks for the info! thought that might be the case.


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  Reply # 1511157 11-Mar-2016 10:54
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Adamww:

 

I have some interesting experience I will share, a bit of a long story though… So in short I would say if you can get away without cooling and have mains gas avail to your property then a ducted gas system wins hands down.

 

 

 

Horses for courses, I guess! For people in warmer/muggier locations the aircon aspect may be a strong pull towards the heatpump - and even in places with relatively benign climates like where I live (PN), the aircon can be invaluable - eg a number of nights over this weirdly warm summer we've been able to make the bedrooms far more liveable by using the aircon.

 

Are there gas systems that allow for full remote (off-site) operation?

 

Personally, I'm happy with how quickly our ducted heatpump warms the rooms. It does take careful installation to ensure the ducts are put in the right places, though, to ensure both even airflow distribution and ensuring it doesn't blow down where people are sleeping, for example.

 

Adamww:

 

I don’t think you would be able to sleep with a ducted heat pump on

 

 

Depends on the sleeper, I think; the rest of my family don't seem to have any issue with sleeping when ours is on, whereas I do find I have a more disrupted sleep. That said, when the fan speed is on low there isn't a strong air current coming out of the vents - possibly it's the background noise I can pick up?


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  Reply # 1511161 11-Mar-2016 10:56
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I dont even really notice my ducted heat pump system is on (noise level wise, comfort wise of course I do :))....


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  Reply # 1511180 11-Mar-2016 11:14
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4.5kw is a fairly small heat pump, mine's closer to 10kw. A heat pump too small will be noisy and less efficient. My wife who's from the UK doesn't really like heat pumps much, proper central heating is quieter, more effective, and probably cheaper, with the downside that it may take some wall space for radiators.

 

My bigger heat pumps can make a noticeable different to room temperature within a few minutes. The run for a while though, because while heating the air is easy that air then warms the objects in the room which have more mass, plus of course the walls and such. 

 

It may be that heating is more important than cooling, but every year gets a little warmer...





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  Reply # 1511199 11-Mar-2016 11:45
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jonathan18:Horses for courses, I guess! For people in warmer/muggier locations the aircon aspect may be a strong pull towards the heatpump - and even in places with relatively benign climates like where I live (PN), the aircon can be invaluable - eg a number of nights over this weirdly warm summer we've been able to make the bedrooms far more liveable by using the aircon.

 

Yes, I agree that's why my first sentence qualified that by "if you can get away without the cooling".  I think house design as well as location are factors here.  Incidentally you can get cooling add-ons for a gas system but I bet they are not cheap.

 

jonathan18:Are there gas systems that allow for full remote (off-site) operation?
  I went for Bonaire (cheapest and installer gave me the most confidence), it has an optional "interface box" for connecting to home automation.  It appears pretty basic, just on/off and temp adjustment, you couldn't for instance turn individual zones on or off etc. 

 

timmmay:

 

4.5kw is a fairly small heat pump, mine's closer to 10kw. A heat pump too small will be noisy and less efficient. My wife who's from the UK doesn't really like heat pumps much, proper central heating is quieter, more effective, and probably cheaper, with the downside that it may take some wall space for radiators.

 

My bigger heat pumps can make a noticeable different to room temperature within a few minutes. The run for a while though, because while heating the air is easy that air then warms the objects in the room which have more mass, plus of course the walls and such. 

  You misunderstood what I said.  My heat pump was rated at 7.5Kw system.  What I was trying to say is that based on my gas use my "room" needed about 4.5Kwh of heat to keep it at equilibrium.

 

timmmay: It may be that heating is more important than cooling, but every year gets a little warmer...

 

@ 0.92°C per 100 years in NZ its probably something not worth factoring into your heating decision.


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  Reply # 1511256 11-Mar-2016 12:29
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Ah ok, 7.5kw is pretty decent. I'm not talking about official figures re warming, but it feels like every year we're using the air conditioner a little more, earlier and later in the year, for longer each day. I have an old house though, modern houses with better insulation and more thermal mass may be better.





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  Reply # 1511641 11-Mar-2016 22:44
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If you want to automate a gas ducted central heater - often this will be very easy if you have an existing home automation setup. As alot of gas central heaters can be connected to simple thermostats, that simply join 2 wires together to make the heater go. (thermostat has an inbuilt relay) So assuming your HA system can measure room temp and do timers. Then the rest is easy.

 

 

 

And often dampers are controlled by the heater simply switching power on and off to the dampers. So again easy to control. You just need some rules to stop all dampers from being closes at the same time. Unless you have some areas that are not controlled by the dampers.

 

And Add on aircon often works by simply telling the central heater to run in fan only mode. And then by switching on the aircon unit. (a 3rd wire to the central heater for "fan only" mode)






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  Reply # 1511662 11-Mar-2016 23:15
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Adamww:

But the big difference was the comfort level and this I believe is due to the big difference in discharge temp between the two technologies. The air coming out of the heat pump is only about 35-38°C compared to the gas at 85°C.



Have you got some data showing supply air temps of 85 degrees C for gas central heating? I've never really worked with domestic gas heating but I've never seen any form of air-conditioning run at that sort of supply air temperature.

Aside from that I totally agree about gas heating being highly under rated, especially in colder climates.

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  Reply # 1511726 12-Mar-2016 08:13
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Handle9:

Have you got some data showing supply air temps of 85 degrees C for gas central heating? I've never really worked with domestic gas heating but I've never seen any form of air-conditioning run at that sort of supply air temperature.

Aside from that I totally agree about gas heating being highly under rated, especially in colder climates.

 

The 85°C figure came from my Rinnai space heater.  I measured that with a cooking thermometer and remember a similar figure was also mentioned as one of the tests in the install manual.  I would imagine with a ducted system with 20 or more meters of duct, several dampers and Y connections etc that it will be nowhere near that coming out of the floor register. 


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  Reply # 1511734 12-Mar-2016 08:25
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Adamww:

Handle9:

Have you got some data showing supply air temps of 85 degrees C for gas central heating? I've never really worked with domestic gas heating but I've never seen any form of air-conditioning run at that sort of supply air temperature.

Aside from that I totally agree about gas heating being highly under rated, especially in colder climates.


The 85°C figure came from my Rinnai space heater.  I measured that with a cooking thermometer and remember a similar figure was also mentioned as one of the tests in the install manual.  I would imagine with a ducted system with 20 or more meters of duct, several dampers and Y connections etc that it will be nowhere near that coming out of the floor register. 



OK that makes more sense. If won't be 85 degrees on the air side of the heat exchanger, most ducted air conditioning (hot water or refrigerant) is limited to around 35 degrees. The ducting doesn't like it and neither would the occupants. The difference is gas systems can get to 35 degrees off coil very fast when it's cold outside unlike dx systems.

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  Reply # 1512960 14-Mar-2016 12:24
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Handle9:
OK that makes more sense. If won't be 85 degrees on the air side of the heat exchanger, most ducted air conditioning (hot water or refrigerant) is limited to around 35 degrees. The ducting doesn't like it and neither would the occupants. The difference is gas systems can get to 35 degrees off coil very fast when it's cold outside unlike dx systems.

 

I just gave it a 5 min run this morning out of curiosity.  I checked at two vents at each end of the house, got 59 & 63°C air temp coming through the floor grills.  Some of the vents nearer the furnace may be slightly hotter.


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