Question about ducted heatpumps

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foobar

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#119359 29-May-2013 12:50

Hello!

A few questions about ducted heating/cooling. Please let me describe the situation first.

We are in the process of getting a new house built (Auckland area) and are considering our options for heating/cooling. The house probably will have a normal, wall-mounted heat pump downstairs, where the house has an open plan. So, I can see how his can work well for downstairs.

However, upstairs we have the bedrooms and bathrooms and I don't see how a downstairs wall-mounted unit can help to heat/cool those rooms, especially with the doors closed.

So, we are considering adding a second heat-pump for upstairs, this time of the ducted variety, which would then be able to get warm/cool air into the various upstairs rooms, even with the doors closed.

I'm under the impression that it shouldn't be too expensive to have the ducting added upstairs, since the ducts/pipes can run through the attic, but I could be wrong. At least it should be cheaper than getting ducts incorporated into the 1st floor ceiling.

Now my questions:

What do you think about the idea of adding a second heat-pump for the top floor, rather than having one, large heat-pump, partially or fully ducted for the whole house? Inefficient? Good idea? Bad idea?
What prices should I expect for a ducted heat-pump upstairs (around 90 sqm area, 4 rooms, 2 bathrooms)?
Which manufacturers could you recommend?

Thank you very much for any insight!

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#827705 29-May-2013 13:04

Have you considered central heating with radiators, perhaps driven by a large heat pump? Much quieter than a heat pump, and you don't so much air blowing around.

Have you considered integrated heating and ventilation? I'd suggest you contact a specialist firm

Check out the Fujitsu sleep pump. I've heard it advertised for $6K with 3 outlets, and you could probably add more. I can't vouch for it, I've just heard of it.

benmurphy66

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#827706 29-May-2013 13:05

I am in the process of getting quotes for a ducted install and for a similar sized space to what you talk about with good roof space / access.

Looking at $9500 - $13000. (two quotes). Two different opinions on system sizing. I am going to get a couple of quotes

timmmay

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#827708 29-May-2013 13:15

I have a 10kw heat pump in my lounge and 7kw in my kitchen. If I had central heating I'd want no less than 20kw if it was for the whole house.

The sleep pump is 10kw heating, 8.5kw cooling. If that's for 3-4 bedrooms that should be fine, but it wouldn't heat a whole house.

I'd love to get an expert in the area to chime in.

Sounddude

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#827713 29-May-2013 13:33

That sleep pump looks quite interesting! Not much info on the Fujitsu site though :(

mattwnz

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#827717 29-May-2013 13:48

foobar: Hello!

A few questions about ducted heating/cooling. Please let me describe the situation first.

We are in the process of getting a new house built (Auckland area) and are considering our options for heating/cooling. The house probably will have a normal, wall-mounted heat pump downstairs, where the house has an open plan. So, I can see how his can work well for downstairs.

However, upstairs we have the bedrooms and bathrooms and I don't see how a downstairs wall-mounted unit can help to heat/cool those rooms, especially with the doors closed.

So, we are considering adding a second heat-pump for upstairs, this time of the ducted variety, which would then be able to get warm/cool air into the various upstairs rooms, even with the doors closed.

I'm under the impression that it shouldn't be too expensive to have the ducting added upstairs, since the ducts/pipes can run through the attic, but I could be wrong. At least it should be cheaper than getting ducts incorporated into the 1st floor ceiling.

Now my questions:
What do you think about the idea of adding a second heat-pump for the top floor, rather than having one, large heat-pump, partially or fully ducted for the whole house? Inefficient? Good idea? Bad idea?
What prices should I expect for a ducted heat-pump upstairs (around 90 sqm area, 4 rooms, 2 bathrooms)?
Which manufacturers could you recommend?
Thank you very much for any insight!

If it is a new build, how come you aren't looking at under slab underfloor heating? You can hook it up to a heatpump HWC, and it should be more economical than a vented air based heat pump. The other thing you will want to look at is super insulating your house. Make sure the walls use 140x45 framing, and really thick batts witha high R value. It should save you heaps in energy costs.

Batman

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#827728 29-May-2013 13:55

is 13K worth the money? could you get say a gas central heating for that money?

benmurphy66

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#827742 29-May-2013 14:27

joker97: is 13K worth the money? could you get say a gas central heating for that money?

Yeah I won't be paying that. it's pretty strange because of the three companies I have had review our heating requirements we have had three different pros & cons which all conflict with each other.

The GAS central heating came in at $9.5k. for a 8 outlet solution. that is without the costs of getting gas connected. Could use LPG bottles.

The Fujitsu ART45 with 8 outlets (4.2-16.2 kW) came in at $13,300.

Somebody else quoted a small Fujitsu ducted unit for $9,500.

I am just waiting on a quote for a split unit but I expect it to be similar money.

mattwnz

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#827757 29-May-2013 14:34

Gas won't cool, unlike a heatpump. Plus supply could be a problem in the future, and unpredictable costs. A few issues with ducted systems, is that you can end up with a great big horrible vent in the ceiling. They also can make noise, which may not be best for a bedroom.

benmurphy66

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#827758 29-May-2013 14:42

mattwnz: Gas won't cool, unlike a heatpump. Plus supply could be a problem in the future, and unpredictable costs. A few issues with ducted systems, is that you can end up with a great big horrible vent in the ceiling. They also can make noise, which may not be best for a bedroom.

Yeah those are the comments I got from the heat pump people too when I brough up Gas. :) They seemed to suggest the cost of the gas connection alone in summer would pay for the heat pump in winter.

Then the Gas guy would say remember a heat pump will only last you 10 years max.

I hate it when sales information is so conflicting.

Re the thought about vents etc. I agree however it might be better than having a larger unit on each wall.

mattwnz

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#827768 29-May-2013 14:49

benmurphy66:
mattwnz: Gas won't cool, unlike a heatpump. Plus supply could be a problem in the future, and unpredictable costs. A few issues with ducted systems, is that you can end up with a great big horrible vent in the ceiling. They also can make noise, which may not be best for a bedroom.

Yeah those are the comments I got from the heat pump people too when I brough up Gas. :) They seemed to suggest the cost of the gas connection alone in summer would pay for the heat pump in winter.

Then the Gas guy would say remember a heat pump will only last you 10 years max.

I hate it when sales information is so conflicting.

Re the thought about vents etc. I agree however it might be better than having a larger unit on each wall.

Although a unit on the wall probably does less damage to the house structurally. Plus heat rises. You can get some units that sit near the floor, and look more like wall heaters. You can also now get designer looking ones. The problem with ceiling systems is they have to fit in in between the structure, so you probably won't get the outlets exactly where you want them. I have seen a bad install before in a living room. And if you have to take it out in the future, there is some major gibbing and painting work to be done.
Not sure about the 10 year life, I would have thought it should be better than that.

Handle9

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#827785 29-May-2013 15:30

Regardless of which way you go you will have compromises. If I was building a two story house I would look probably go for a heatpump system. I'd look at a multi head (multiple indoor units and a single compressor) unit for the ground floor and some form of ducted split system upstairs.

A ducted system is far superior to high wall or console system as the don't take any wall space, and the outlets can be mounted in the middle of the space, to provide maximum throw and prevent stratification. The issues you have are if the indoor unit has to be replaced, you need a way of accessing the roof space. This could be through a hatch, or if you have a tile roof, by removing tiles and going through the roof. it's not a huge job either way, if you have the house structure designed with this in mind, and if the indoor unit is installed before the ceiling gib.

I wouldn't bother with a ducted system for the ground floor as you will have to build the ceiling : floor space bigger to accommodate ductwork. Piping in wall for high wall/console system is more practical. If you really wanted roof mounted units in ground floor situation you could use cassettes but IMO they are fugly and appear huge in a normal domestic stud height. They work pretty well though.

The one issue you must be aware of with using a ducted system is that all the spaces get the same supply air temperature - i.e. they all get heating or all get cooling. You can fit a zone damper kit to close off individual zones however you can't have different temperature control for each room. You either pick a representative room to control off (i.e. master bedroom or lounge) or do averaging sensors. Either solution has it's issues however unless you have individual units in each room then thems the breaks.

If you want a cheap solution then a Temperzone ducted split will be your best bet, however these are not inverter controlled. If you want something more sophisticated then one of the Japanese brands will do the job.

10 year economic life is about right for any domestic split system, particulalry if it is never serviced. Generally you can't get parts after that period so if one component fails then you have to replace the whole lot (you can reuse the pipework and electrical wiring though). Some systems will last longer but I wouldn't plan on it.

If I was building a single level house, and reticulated gas was an option, I'd look at a in slab hydronic (ie water piped in your slab) with a gas calorifier which could also be used for domestic hot water. If gas prices rose to an uneconomic level then it could be replaced by a hotwater heat pump however the paybacks on those are too long compared to gas, for the next few years anyway. If you can combine your domestic hotwater and room heating source then that is a really nice solution which can work well.

benmurphy66

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#827789 29-May-2013 15:35

nice summary :)

mattwnz

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#827790 29-May-2013 15:37

Handle9:

If I was building a single level house, and reticulated gas was an option, I'd look at a in slab hydronic (ie water piped in your slab) with a gas calorifier which could also be used for domestic hot water. If gas prices rose to an uneconomic level then it could be replaced by a hotwater heat pump however the paybacks on those are too long compared to gas, for the next few years anyway. If you can combine your domestic hotwater and room heating source then that is a really nice solution which can work well.

Combining them though is expensive. I looked at a couple of companies, one had a combined system, which was all computer controlled and was about 60k. The other system wasn't combined, and was less than half the price.

Handle9

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#827824 29-May-2013 16:16

mattwnz:
Handle9:

If I was building a single level house, and reticulated gas was an option, I'd look at a in slab hydronic (ie water piped in your slab) with a gas calorifier which could also be used for domestic hot water. If gas prices rose to an uneconomic level then it could be replaced by a hotwater heat pump however the paybacks on those are too long compared to gas, for the next few years anyway. If you can combine your domestic hotwater and room heating source then that is a really nice solution which can work well.

Combining them though is expensive. I looked at a couple of companies, one had a combined system, which was all computer controlled and was about 60k. The other system wasn't combined, and was less than half the price.

That's not the solution I've seen then :)

DarthKermit

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#827838 29-May-2013 16:18

A friend of mine has a heat pump in his lounge and a duct to suck the warm air from the lounge and into the hallway and one bedroom.

He said that it's very inefficient at transferring the heat from one place to the other.

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