Heat Pump Thoughts

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#1341875 13-Jul-2015 07:23

Stan: The new Dikans US7s are crazy efficient

They're slightly more efficient than my 3 year old Fujitsu Nocria. The smaller ones always have higher efficiency, but I suspect that if you oversize your heat pump slightly and have it run at a moderate setting rather than high it stays in its most efficient zone.

lissie:
timmmay:
lissie: Yeah I wasn't the idiot that installed it - if I did buy one I'd only ever consider one installed near to the floor - basic physics - particularly iwth a cathedral ceiling. The room never gets to temperature - the only time it stops blowing - is when its defrosting! To be fair given a few hours it will warm the room unassisted - and to my amazement the power bill was under $300 last month - all of which was cold - so that was an awful lot better than expected.

It has been inspected - there is nothing wrong with it

What make and model is it? What's the rated heat output? How large is your room and how well insulated? Really does sound faulty or way underpowered. I have high ish ceilings (not cathedral) and a very old house, but I've insulated well. My 10kw Nocria, while a bit loud, heats it quickly and easily.

Carrier 6kw heating - the room isn't huge 5m x 5.3m - open (thru an archway to a dining room about 3.2 x 2m The log burner warms it easily - indeed so does the 2.5 kw fan heater I have! Large windows single glazed, the cathedral ceiling appears to have no insulation - going to fix both of those things before we do anything with heating.

It's faulty or it's rubbish. If a heat pump with a claimed 6kw output is beaten by a 2.4kw fan heater, it's faulty, regardless of what anyone says. In that situation I'd expect the room to be significantly warmer 10 minutes after the heat pump went on, and in half an hour the room should be up to heat.

Next step is everything in the room has to come to equilibrium with the air temp, which drags the air temp down and means it needs to be heated again.

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#1341891 13-Jul-2015 07:57

lissie: Carrier 6kw heating - the room isn't huge 5m x 5.3m - open (thru an archway to a dining room about 3.2 x 2m The log burner warms it easily - indeed so does the 2.5 kw fan heater I have! Large windows single glazed, the cathedral ceiling appears to have no insulation - going to fix both of those things before we do anything with heating.

a fire will work much more effectively because its rated at soemthing like 15+kw so it heats quickly, the problem is over heating.

the electric fan quick because its on the ground at the lowest point heating the coolest air. the hot air rises forcing cooler air down to the floor where it is heated again

The heat pump, because its high on the wall will struggle to heat the lowest air and because you have high ceilings it just ends up heating the air above head height. maybe try a ceiling fan or point the heat pumps directional vanes at the ground to try and stir the air up a little more.

E3xtc

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#1341892 13-Jul-2015 08:04

Just to add my 2 cents in. We had a Mitsubishi heat pump in our last house (age of heat pump about 10 years back), and now in a different house have a 5 year old Fujitsu Nocria (for the bottom level) and a Ducted Panasonic unit (for the upper level). In terms of noise I would rate them all pretty similar - after all it's air moving. In terms of ease of use, again I would rate them all pretty much the same - similar buttons, similar functions...it's not rocket science. Who knows about real world power usage and heating effectivness because they are all in different areas, and at different times - so meh what will be will be :P
If I was purchasing again, it would come down to some basics like the technical specifications of the units (eg Kw rating, db noise levels, etc), and if there is some specific features that you want, then look out for those...and then focus on getting the best price from the best installer...actually, in saying that, I rekon the installer part of the equation is possibly one of the biggest parts - so make sure you do your homework there and don't get some numpty muppets in :) (we had these guys do our ducted one upstairs http://www.heatpumpsauckland.co.nz/ and would recommend them as they took care and time to do the job right first time up - well impressed)

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#1341894 13-Jul-2015 08:06

Jase2985:
lissie: Carrier 6kw heating - the room isn't huge 5m x 5.3m - open (thru an archway to a dining room about 3.2 x 2m The log burner warms it easily - indeed so does the 2.5 kw fan heater I have! Large windows single glazed, the cathedral ceiling appears to have no insulation - going to fix both of those things before we do anything with heating.

a fire will work much more effectively because its rated at soemthing like 15+kw so it heats quickly, the problem is over heating.

the electric fan quick because its on the ground at the lowest point heating the coolest air. the hot air rises forcing cooler air down to the floor where it is heated again

The heat pump, because its high on the wall will struggle to heat the lowest air and because you have high ceilings it just ends up heating the air above head height. maybe try a ceiling fan or point the heat pumps directional vanes at the ground to try and stir the air up a little more.

That makes sense - not that we've had problems with over-heating with the log burner- and I totally agree it makes no sense to mount a heater high on the wall - so why are most HP installed like that? That's how they are instaled overseas - but that's for use as air conditioning! As they are marketed as heaters here Idon't understand why they are aren't installed at floor level

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#1341898 13-Jul-2015 08:14

I have an older Toshiba which works pretty well - I just added a Pebble Air wifi controller so that I can control it remotely and also have extra timers. Was a little pricey at $270 but it's Kiwi made and works very well.

As I am driving home I can check the temperature of the house and set the Heatpump up so when I get home it's toasty.

Matt.

Jase2985

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#1341900 13-Jul-2015 08:17

lissie: That makes sense - not that we've had problems with over-heating with the log burner- and I totally agree it makes no sense to mount a heater high on the wall - so why are most HP installed like that? That's how they are instaled overseas - but that's for use as air conditioning! As they are marketed as heaters here Idon't understand why they are aren't installed at floor level

Because most people dont have high ceilings as the standard ceiling height in NZ is 2.4m. It doesnt take long to heat a normal sized room.

also im pretty sure they are designed to work best from 6-10in from the ceiling height and it also means they can be mounted over a window/door and you can place furniture under them and your not wasting floor space by having them at floor level.

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#1341904 13-Jul-2015 08:23

lissie: That makes sense - not that we've had problems with over-heating with the log burner- and I totally agree it makes no sense to mount a heater high on the wall - so why are most HP installed like that? That's how they are instaled overseas - but that's for use as air conditioning! As they are marketed as heaters here Idon't understand why they are aren't installed at floor level

I guess they're mounted high on the wall so they don't get in the way, as they're typically retrofitted. New homes should have central heating, either ducted or radiators.

The high wall ones do point the heated air down towards the floor, and in air condition mode they air higher.

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#1341906 13-Jul-2015 08:24

When a wall mounted heat pump is on heat it has the vents set up to push air towards the ground. I would wonder if floor vs wall mount really makes a whole lot of difference.

lissie

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#1341907 13-Jul-2015 08:27

Jase2985:
lissie: That makes sense - not that we've had problems with over-heating with the log burner- and I totally agree it makes no sense to mount a heater high on the wall - so why are most HP installed like that? That's how they are instaled overseas - but that's for use as air conditioning! As they are marketed as heaters here Idon't understand why they are aren't installed at floor level

Because most people dont have high ceilings as the standard ceiling height in NZ is 2.4m. It doesnt take long to heat a normal sized room.

also im pretty sure they are designed to work best from 6-10in from the ceiling height and it also means they can be mounted over a window/door and you can place furniture under them and your not wasting floor space by having them at floor level.

That makes less sense - even if the windows were double glazed - and most NZ houses aren't - the heat is going straight out the window! Anyway you can just as easily place a heater below a window (see any UK house with radiators)

The rest of the house is 2.4m - just not this room! We are retrofitting insulation (on the inside) and installing a ceiling fan (to help the log burner) - which may help the HP - but at this point it's very close call as to whether we regain the wall space by removing it and installing a gas bayonet for gas.

Yeah I hear you about wall space though - I'm getting rid of the wall lights to regain that!

I help authors publish their books - DIYPublishing.co.nz

lissie

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#1341909 13-Jul-2015 08:30

timmmay:
lissie: That makes sense - not that we've had problems with over-heating with the log burner- and I totally agree it makes no sense to mount a heater high on the wall - so why are most HP installed like that? That's how they are instaled overseas - but that's for use as air conditioning! As they are marketed as heaters here Idon't understand why they are aren't installed at floor level

I guess they're mounted high on the wall so they don't get in the way, as they're typically retrofitted. New homes should have central heating, either ducted or radiators.

The high wall ones do point the heated air down towards the floor, and in air condition mode they air higher.

Well I guess if you can afford to build a new house - you can afford the bills to run central heating! We live near an area of high spec builds houses (Aotea, Porirua) - and I've been to a few stealing design ideas - they generally just have a couple of high-wall mounted heat pumps- I've not seen central heating.

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Jase2985

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#1341913 13-Jul-2015 08:41

what do you mean "afford the bills to run central heating"?

its cheap compared to other sources to run

http://www.mitsubishi-electric.co.nz/heatpump/group.aspx?cat=7972
it all lives in the roof or under the floor and has a single indoor and outdoor unit and its ducted to each room.

very efficent

lissie

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#1341924 13-Jul-2015 09:00

Jase2985: what do you mean "afford the bills to run central heating"?

its cheap compared to other sources to run

http://www.mitsubishi-electric.co.nz/heatpump/group.aspx?cat=7972
it all lives in the roof or under the floor and has a single indoor and outdoor unit and its ducted to each room.

very efficent

Compared to heating the hold house withplug in electric heaters yes it's cheaper - which doesn't mean that you are going to have bills under about $700/month in winter! You'll have a warmer house sure - but that doesn't mean you can afford to run it.

If I was building a house it would have passive solar gain slabs and the correct orientation to minimize the power billl - not central heating

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#1341939 13-Jul-2015 09:16

well my parents bill was less than $300 a month in winter when they were in chch. that was 2 heat pumps and a DVS running 24/7. Single glazing in a ~10 year old house.

must be doing something really wrong if your getting a $700 a month bill.

I think your making a lot of assumptions on things.

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#1341944 13-Jul-2015 09:23

Consumer NZ has a 4.5kw heat pump costing $.43 per hour at maximum heat, 24 hours = $10.32 per day. thats running at maximum heat output which would be the first hour of turning it on then it would be cheaper.

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#1341973 13-Jul-2015 09:59

The feedback I've heard with the pellet fires is they are good and all, but require an electric motor to deliver the pellets, so don't work if the power is out?
It's mechanical too, so reliability might be an issue, and you're locked into the one type of fuel, at whatever cost that may be at.

Heat pumps are just fan heaters, there's nothing more to them on the inside.
The clever bit is the efficiency of the heat source, which is much more efficient than a standard electric fan heater.
That efficiency does drop off though as the difference between the outside temp and the desired indoor temp increases.
So when it's really cold outside, you won't be able to heat at the 300% efficiency the sales material has slapped all over it.

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