Heat Pumps - How Directional Are They?

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Oubadah

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#79193 14-Mar-2011 17:44

We've had a quote from Fonko, and they want to position the unit so it's in the lounge, on the wall opposite the hallway door. The guy appeared to think that the unit would project heated air directly down the hallway. Anyway, this particular location isn't going to be the most aesthetically pleasing.

It's got me wondering just how directional these heat pumps are - I mean, is it realistic to think that it'll project air, you know... 'line of sight' through a standard doorway and down a 10M hallway? Is there any merit to such positioning?

Any advice would be much appreciated, or even if you could direct me to a good international forum that specialises in the topic...

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#448285 14-Mar-2011 17:52

www.ecobob.co.nz is a great (and local) resource for all things like this.

hellonearthisman

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#448295 14-Mar-2011 18:36

Yes, it would pump head through the doorway. I have one that is opposite a door in my lounge (4m from door) but I can feel the heat/cooling it generates through that door (like another 3m) They do generate a fair bit of flow when they get going.

nate

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#448300 14-Mar-2011 19:08

hellonearthisman: Yes, it would pump head through the doorway. I have one that is opposite a door in my lounge (4m from door) but I can feel the heat/cooling it generates through that door (like another 3m) They do generate a fair bit of flow when they get going.

+1

When I used to sit infront of the pump in our office it was miserable (too cold in summer, too hot in winter), and I was a good 7/8m away.

richms

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#448305 14-Mar-2011 19:29

Very directional. They are not amazing devices. If you get a 5kW one, it will basically be like sitting 2 fan heaters in the location that the indoor part is. If you get a 7kW, then it will be like 3 fan heaters roughly. Some have a swing vent but its very hard pressed to get heat to travel around corners etc.

Richard rich.ms

Oubadah

676 posts

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#448308 14-Mar-2011 19:36

Yes, well from where it's going to be situated, it's 4M across the lounge then ~10M to the end of the hall (the two bedrooms that will also be relying on this unit are opening on to the hall about 6M and 8M down). The house does have a very high stud too.

My main concern is the stairwell to the second story. It's just inside the hall, and I'm concerned that a large amount of the heated air will go straight up the stairwell (there is already another unit installed for the upstairs).

The downstairs unit he quoted for is the second largest in Mitsubishi's line though (10.5KW "heating capacity"), to I guess we should be OK...

richms

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#448312 14-Mar-2011 19:48

Oubadah: Yes, well from where it's going to be situated, it's 4M across the lounge then ~10M to the end of the hall (the two bedrooms that will also be relying on this unit are opening on to the hall about 6M and 8M down). The house does have a very high stud too.

My main concern is the stairwell to the second story. It's just inside the hall, and I'm concerned that a large amount of the heated air will go straight up the stairwell (there is already another unit installed for the upstairs).

The downstairs unit he quoted for is the second largest in Mitsubishi's line though (10.5KW "heating capacity"), to I guess we should be OK...

Not if you are going to be paying to run it at full tilt only to have the heat in the wrong place.

There is no way you will have an efficient heating system trying to heat the bedrooms like that. Might have some remnant heat from the rest of the house if you leave their doors open etc, but come night time when you close them, you are back where you were without the heatpump. IME from the last place I was in with one, trying to heat one room from one in another room is a waste of time. If I get one here it will be ducted or nothing.

Richard rich.ms

Oubadah

676 posts

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#448348 14-Mar-2011 21:15

richms:
Oubadah: Yes, well from where it's going to be situated, it's 4M across the lounge then ~10M to the end of the hall (the two bedrooms that will also be relying on this unit are opening on to the hall about 6M and 8M down). The house does have a very high stud too.

My main concern is the stairwell to the second story. It's just inside the hall, and I'm concerned that a large amount of the heated air will go straight up the stairwell (there is already another unit installed for the upstairs).

The downstairs unit he quoted for is the second largest in Mitsubishi's line though (10.5KW "heating capacity"), to I guess we should be OK...

Not if you are going to be paying to run it at full tilt only to have the heat in the wrong place.

There is no way you will have an efficient heating system trying to heat the bedrooms like that. Might have some remnant heat from the rest of the house if you leave their doors open etc, but come night time when you close them, you are back where you were without the heatpump. IME from the last place I was in with one, trying to heat one room from one in another room is a waste of time. If I get one here it will be ducted or nothing.

I know about ducted heat pumps, and I asked the guy, but he laughed and said they were 20K or something ridiculous. Otherwise, I think you can get systems with more than one interior head unit (whatever they call them) running off a single external (condenser?) unit. But I suppose they cost a fortune too...

The only other thing I can think of is installing a recirculation system (you know, like DVS but I'd do it DIY) to pick up air from the rooms with the heat pump and distribute it to the bedrooms via ducting. That seems like a half arsed 'band aid' solution though.

What would you do?

Oubadah

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#448376 14-Mar-2011 21:52

http://www.trademe.co.nz/Building-renovation/Heating-cooling/Air-conditioning/auction-361435789.htm

That ducted unit is fairly pricey, but not as bad as I expected.

I guess one could use it in multi room applications, but there would be no control over the individual rooms.

richms

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#448377 14-Mar-2011 21:54

Friend tried the heat transfer kit from the massive one that the govt subsidized to be installed in the main living area, and it was useless. It transfered the heat from the fireplace fine, but that was really really hot at cieling height where it sucked it in, but the heatpump is blowing down, and the air from it is at best tepid once that room had settled at 24? so the air coming out in the bedroom was barely above what you wanted the bedroom to be.

Depending on where you are and how cold it is, if the bedrooms are well insulated and not large, you will probably never have a payback on heatpumps in them, but you do gain cooling in summer which is always nice to have.

The lack of payback in bedrooms is why they guy said they wouldn't subsidize them to be installed there. Considering I am only ever in my workspace or bedroom in winter, I would get zero benifit from one in the lounge/dining area.

When I priced up the multiple inside units off one outdoor one, they were no cheaper than 2 small systems, and had a problem that you could not heat in one and cool in the other, and when cooling if one wanted to defrost the cooling stopped in the other one while it did it etc.

Richard rich.ms

timmmay

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#448449 15-Mar-2011 09:23

Yes, it'll blow air down the hall fine. I have a heat pump on a wall that blows through a really wide doorway, then goes left down the 5m hallway. From there the heat turns another corner and goes into my room. It doesn't do the 180 degree turn quickly, but it does effectively warm that whole end of the house - big lounge, big hall, and three big bedrooms.

I have an 8kw unit, I love it. I know that in theory it puts out about as much heat as 4 fan heaters (which I measured at 2kw with a power meter), but it feels a lot more effective. If I turn the heat pump on, within 15 minutes the whole end of the house is whatever temperature I want it. It does more in 10 minutes than a fan heater does in an hour, perhaps because they have good fans in them.

I like my Daikin unit. I don't like my friends Mitsubishi unit, the indoor unit doesn't seem quite as easy to control, or easy to direct the warm air.

If I was doing it again i'd get a ducted unit.

Oubadah

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#448457 15-Mar-2011 09:40

I don't understand why the ducted unit's generally cost more than the multi head systems

minimoke

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#448458 15-Mar-2011 09:42

OP - your situation sounds similar to ours. The first question I'd want answering is "Will the one heat pump realistically heat both the lounge AND the hall and bedrooms.

We have a big Mitsubishi in our lounge. Its quiet and you don't feel the air movement. But we keep the lounge door closed so the heat doesn't escape down the hall. We also leave the heat pump on all the time. During the day it cycles infrequently because of the solar gain in this area. During the night it cycles only to keep the temperature constant - not too hard to do with the double glazing and thick insulation we have.

Down the hall we have a seperate heat pump which blows directly down the hall with the aim of heating the bedrooms. This only get turning on in the evening and gets turned off in the morning. The bedrooms closest to the pump are toasty warm - the ones furthest away (some 10m + away) get the chill taken off them. The pump doesn't cause a draft and its quiet enough not to disturb sleep.

(we're in Christchurch - so it get s a bit nippy in winter!)

timmmay

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#448462 15-Mar-2011 09:57

Leaving a heat pump 24/7 is a great way to really jack your power bill. With good insulation I don't need it, though I might consider it if I had a wee baby. I make use of the timer, and i'd really like a better weekly timer for my heat pump. I think you can get them now, mine's a couple of years old.

Heat pumps will heat quite a large area if you get a big enough one, just don't expect it to be really really fast.

I guess ducted units have a lot more labour, plus they're probably bigger, and sell in lower volumes.

Jaxson

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#448501 15-Mar-2011 11:32

minimoke: "Will the one heat pump realistically heat both the lounge AND the hall and bedrooms.

We have a big Mitsubishi in our lounge. Its quiet and you don't feel the air movement. But we keep the lounge door closed so the heat doesn't escape down the hall. We also leave the heat pump on all the time. During the day it cycles infrequently because of the solar gain in this area. During the night it cycles only to keep the temperature constant - not too hard to do with the double glazing and thick insulation we have.

Down the hall we have a seperate heat pump which blows directly down the hall with the aim of heating the bedrooms. This only get turning on in the evening and gets turned off in the morning. The bedrooms closest to the pump are toasty warm - the ones furthest away (some 10m + away) get the chill taken off them. The pump doesn't cause a draft and its quiet enough not to disturb sleep.

+1 to the above.

A heat pump is just a fan heater, only it gets it's cooling/heating from a source outside instead of an electric element. They are fan heaters of different capacities for sure but it's not going to magically travel throughout a house.

We found the same with heat transfer systems. They only really work well if the supply heat is very hot. They work fine for air ciruculation, but you'd really want to insulate the ducts a lot better if you wanted to make this work with a heatpump/fan heater source instead of an wood fire.

vexxxboy

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#448506 15-Mar-2011 11:46

my heat pump has modes for every direction of air flow you want, it has settings for fan speed, Vane, Wide vane, Swing and long mode and then if you want to get serious it has a powerfull button which really cranks the airflow up but i tend to set everything to auto and dont touch it

Common sense is not as common as you think.

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