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timmmay
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  #507900 17-Aug-2011 13:34
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My Daikin works really well, a 6-7kw unit heats a large lounge, hallway, and three bedrooms. It can take a couple of hours to heat the whole place, as there's a couple of corners for the air to get around. It seems like a quality, heavy duty unit. If I was doing it again I might go a little larger, as it runs constantly when it's really cold, but at moderate outside temperatures it spends more time off than on.

I'm about to take out the fireplace, which is just too much bother, and put in another for the kitchen/dining area, and my office. A split unit costs more than twice as much as two single units, but means one less outdoor unit, and space is tight. Having the whole house warm is really nice.

Insulation is obviously something you need to do before getting a heat pump.



mattwnz
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  #507909 17-Aug-2011 13:41
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Regs: for comparisons sake, i had a ducted gas central heating unit installed for around $8k. It heats the entire house, not just one room, and i costs a similar amount to run as a heat pump given the 6c/kw gas prices versus 25c/kw electricity prices. i can also turn it on and have the whole house warm in about 5 minutes, and it works in the cold!


It doesn't cool though, unlike a heat pump, and gas prices and availability in the future is probably not sustainable. Also it could be more efficient to set it up with a big heat pump. One of the most efficient heating solutions is underfloor heating in a slab, heated by a heat pump, but initial costs are high and can usually only be done during construction

Regs
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  #507918 17-Aug-2011 13:50
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mattwnz:
Regs: for comparisons sake, i had a ducted gas central heating unit installed for around $8k. It heats the entire house, not just one room, and i costs a similar amount to run as a heat pump given the 6c/kw gas prices versus 25c/kw electricity prices. i can also turn it on and have the whole house warm in about 5 minutes, and it works in the cold!


It doesn't cool though, unlike a heat pump, and gas prices and availability in the future is probably not sustainable. Also it could be more efficient to set it up with a big heat pump. One of the most efficient heating solutions is underfloor heating in a slab, heated by a heat pump, but initial costs are high and can usually only be done during construction



Not cooling is a *feature* in my mind..... heat pumps on cooling cycles raise your summer power bill to match the winter one, effectively doubling your annual electricity costs.  

Running a heat pump as an air con also wipes out any 'green' benefits of heat pumps as its definately not greener to run it all year round than to onnly run a heater in winter.

They were talking on the news the other week, said that all the heat pumps running in summer were now causing electricity supply issues in the summer when they never used to have them.  Thats going to push up spot prices faster than you can say "open a window".

If i was building a house from scratch with a slab, i would definately take a heat pump heated piped water type of solution.  Hard to retrofit one though.






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  #507921 17-Aug-2011 13:52
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langers1972:
Regs: for comparisons sake, i had a ducted gas central heating unit installed for around $8k. It heats the entire house, not just one room, and i costs a similar amount to run as a heat pump given the 6c/kw gas prices versus 25c/kw electricity prices. i can also turn it on and have the whole house warm in about 5 minutes, and it works in the cold!


Warm the whole house, are you mad?

Why do that when you can pay half as much and have a heatpump heat a single room (as long as it's not cold enough to stop it working efficiently which is precisely when you WANT it to work) and leave the rest of the house like an igloo Wink

Is yours a Brivis?


Yep, a brivis:

HE20i Brivis gas fired central heating system (5.3 star rating @ 93%efficiency) with 10 floor mounted outlets


 




timmmay
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  #507924 17-Aug-2011 13:52
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Having the capability to use an air conditioner doesn't mean you have to use it. I find I use mine half a dozen times in summer, on the really hot days when I come home late, compared with running it as a heater constantly in winter.

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  #507929 17-Aug-2011 13:55
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timmmay: Insulation is obviously something you need to do before getting a heat pump.


before you install *any* type of heating really.  Our average indoor temperature went from around 8-10degC up to 17degC after fitting underfloor and boosting the ceiling insulation.  The underfloor made a huge difference as we have bare timber floors.

as for savings, simple math:

power cost to heat 8degC to 20degC >>>>>> power cost to heat 17degC to 20degC 




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  #507931 17-Aug-2011 13:56
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timmmay: Having the capability to use an air conditioner doesn't mean you have to use it. I find I use mine half a dozen times in summer, on the really hot days when I come home late, compared with running it as a heater constantly in winter.


very true, but most people are lazy and once they start, it becomes a habit.  especially when you set things to "auto" 




 
 
 

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Regs
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  #507932 17-Aug-2011 13:56
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timmmay: Having the capability to use an air conditioner doesn't mean you have to use it. I find I use mine half a dozen times in summer, on the really hot days when I come home late, compared with running it as a heater constantly in winter.


very true, but most people are lazy and once they start, it becomes a habit.  especially when you set things to "auto" 




wreck90
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  #507940 17-Aug-2011 14:14
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mattwnz:
Regs: for comparisons sake, i had a ducted gas central heating unit installed for around $8k. It heats the entire house, not just one room, and i costs a similar amount to run as a heat pump given the 6c/kw gas prices versus 25c/kw electricity prices. i can also turn it on and have the whole house warm in about 5 minutes, and it works in the cold!


It doesn't cool though, unlike a heat pump, and gas prices and availability in the future is probably not sustainable. Also it could be more efficient to set it up with a big heat pump. One of the most efficient heating solutions is underfloor heating in a slab, heated by a heat pump, but initial costs are high and can usually only be done during construction


Don't talk to me about underfloor heating.....my gas bill is $450 a month (in summer it is around $60 a month).

When I complained to the architect (new house, and he told me about the wonders of efficient underfloor heating) they got the uber-experts around to check out the installation...they changed the heating system, maybe helped a little but, definitely very expensive still. 

My total gas+electricity in winter is now around $700 -$800 .   This is a 3 year old house. I'm really annoyed . 

timmmay
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  #507946 17-Aug-2011 14:19
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A modern house entirely heated by electricity should be at maybe $300 a month, tops. $800 means something's very wrong, somewhere. The trick would be working out what.

langers1972
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  #507955 17-Aug-2011 14:31
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I would bet on crappy insulation, everyone here seems to build to code minimum which is pathetic.

NZ building in general is about 30 years behind the rest of the developed world in terms of materials/design.

We had double glazing in the UK when I was 8, over 30 years ago and over here it's cutting edge technology. Central heating, what's that?!!!!!!!!! etc etc

Privoxy
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  #507959 17-Aug-2011 14:33
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underfloor heating 24/7 will do that to your power bill.

mattwnz
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  #507962 17-Aug-2011 14:37
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Regs:


True, it sounds like you did your homework. Somepeople however do love air conditioning, but it probably needs to be ducted to get it cool in the right places.
I think the Chch earthquake, and all the heatpumps that have been installed due to it, could create a major electricity supply problem in the summer, as people use them for cooling. A good efficient woodburner, is also quite a green way to heat your house, as long as you have a good local source of wood.

hellonearthisman
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  #507977 17-Aug-2011 15:04
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The South Island with an energy supply problem. Yeah right...

As for heatpumps cooling, they use a lot less (40% my guess) power in cooling mode than in heating modes. Open a window is nice when there are not heaps of bugs wanting to get in to drink your blood.

timmmay
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  #507980 17-Aug-2011 15:08
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Why are heat pumps more efficient when cooling? In both cases they're moving heat from one side of the heat pump to another, rather than creating or destroying heat.

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