Heat Pumps

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networkn

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Topic # 242669 8-Nov-2018 16:12

After much looking around at ventilation systems and ways to cool my daughters very small bedroom over summer and keep it warm in winter and ideally my wifes office which is even smaller and shares a wall, ventilation systems etc, we just don't think we can do what we want and have decided a heat pump in her room doesn't solve all the issues but will resolve the most pressing.

Because it's such a small room we really want something exceptionally cost effective. We have Mitsubishi and Panasonic in the house currently but I saw a website offering $1699 incl installations 1.7/2.0kw Mitsubishi Heavy Industries and also GREE which are around $1500 installed.

Anyone have experience with either or comments etc?

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Reply # 2122267 8-Nov-2018 16:24

That's an extremely small heat pump. Could you have one pointed at both doors? We find heat and cooling travels around corners and through doors, slowly. It won't cool a room that gets direct sun though, and isn't helpful if you want doors closed.

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networkn

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Reply # 2122317 8-Nov-2018 17:46

Unfortunately whilst they share a wall, there isn't really a way to put a heatpump in the hallway.

It's a small heatpump, but it's a small room. 4m x 5M I think from memory.

timmmay

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Reply # 2122354 8-Nov-2018 18:16

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4x5m isn't that small a room. Is the room well insulated, double glazed? Does it get any direct sun at any time of the day? 2kw is probably ok, turn it on in advance and it'll be warm / cool by the time you need it. Undersizing heat pumps can increase power usage though.

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Fred99

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Reply # 2122528 9-Nov-2018 08:34

For a bedroom, you could get one of these:

https://www.daikin.co.nz/our-product-range/split-system-heat-pumps/nexura

The "radiant" mode, they're working (partly) like a convection/radiant heater, the front panel gets warm - not hot (perhaps 50 deg). The fan is still running - but at a very very low setting - so they're not completely silent but close. This on heating mode - on cooling mode I expect it's the same noise as any other heat pump.

I have one of these in a hallway - works well as timmmay suggests to heat bedrooms etc off the hallway - if you leave the door open. Cooling - probably not.

They can be set back into the wall a bit, either by cutting the gib out (which is only going to give 10-12mm) or by cutting back a stud by 50mm or so - only in the case of a non-structural wall.

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Reply # 2122535 9-Nov-2018 08:42

Approx cost?

Fred99

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Reply # 2122538 9-Nov-2018 08:52

I think I paid $3k for the 4.8kw unit, including installation. That was without haggling or shopping around and was on an internal wall - so not "back to back". Not sure how much less expensive the 2.5kw unit would be.

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Reply # 2123578 11-Nov-2018 15:42

Are the heat pumps you are looking at inverters? Variable speed compressors (inverter) are more efficient and have better capacity control.
A rough rule of thumb for cooling is 100 watts per square metre. If you size for cooling you will have plenty of heating capacity.
If getting and inverter try to find the capacity range... for example 0.9 kw to 2.5kw. The lower rating is where the compressor switches on and off.
In a bedroom choose the indoor unit location where it doesn’t blow directly on the person sleeping.

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Reply # 2123975 12-Nov-2018 10:40

Is it possible to buy a heat pump which isn't an inverter model these days? Even the cheapest ones seem to be inverter.

Some models (high wall mount) have passive IR sensors which are supposed to avoid blowing air at you when they're set to "swing". One of ours has this feature, I've no comment on how effective it is, it seems to be effective enough at air circulation at low fan setting which is pretty quiet (not sure if I'd think the same if it was in a bedroom though), so I just set the louvres manually to direct air away from where people sit when it was installed and haven't touched it since.

We have one of the Dyson air-multiplier fans in our bedroom, the new extra quiet model introduced last year, apparently. Couldn't hear it in the shop, very impressive - hence I emptied my wallet. Sounds like the whoosh inside a jet plane cabin when set above 1 (minimum out of 10) in the dead of night. OK - it's probably better than a standard fan - but it's certainly no miracle - and a stupid price. Would I recommend or buy again? Probably not.

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Reply # 2123977 12-Nov-2018 10:45

The room layout is such that there is nowhere I could put it that it won't be blowing air. The two "long" walls are the ones that the dresser and bed are on. If I put it on one wall it would be right above her blowing at the dresser, and if I put it on the other wall, it would be blowing right over the bed.

Window at one short end with no room above the top to sit one, and the other end would still blow onto her.

It's not great.

Kickinbac

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Reply # 2124344 12-Nov-2018 18:19

Fred99:
Is it possible to buy a heat pump which isn't an inverter model these days? Even the cheapest ones seem to be inverter.

Some models (high wall mount) have passive IR sensors which are supposed to avoid blowing air at you when they're set to "swing". One of ours has this feature, I've no comment on how effective it is, it seems to be effective enough at air circulation at low fan setting which is pretty quiet (not sure if I'd think the same if it was in a bedroom though), so I just set the louvres manually to direct air away from where people sit when it was installed and haven't touched it since.

We have one of the Dyson air-multiplier fans in our bedroom, the new extra quiet model introduced last year, apparently. Couldn't hear it in the shop, very impressive - hence I emptied my wallet. Sounds like the whoosh inside a jet plane cabin when set above 1 (minimum out of 10) in the dead of night. OK - it's probably better than a standard fan - but it's certainly no miracle - and a stupid price. Would I recommend or buy again? Probably not.

Fixed speed still available but not common. Generally the cheaper units. MEPS has caused most to disappear.

Kickinbac

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Reply # 2124346 12-Nov-2018 18:26

networkn:
The room layout is such that there is nowhere I could put it that it won't be blowing air. The two "long" walls are the ones that the dresser and bed are on. If I put it on one wall it would be right above her blowing at the dresser, and if I put it on the other wall, it would be blowing right over the bed.

Window at one short end with no room above the top to sit one, and the other end would still blow onto her.

It's not great.

Tricky room. Hot air rises and cool air drops. Generally heat pumps will automatically adjust the vanes to direct air down in heating and horizontally in cooling to mix the conditioned air with the room. Where practical we try to avoid blowing this air directly onto people to minimise discomfort.

blakamin

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Reply # 2124402 12-Nov-2018 19:11

Newer Panasonics have a "shower" mode... blows the cold air across the ceiling instead of straight at you (but will do that if you want too).

bfginger

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Reply # 2132326 23-Nov-2018 03:58

Cheap brand heat pumps may not be very quiet which is going to be a problem in a bedroom.

Cheapest to install doesn't mean cheapest to run. Efficiency varies so the cost in electricity may mount up with an inefficient unit.

Don't place the outdoors unit too close to the bed as it'll be disruptive. Units can support long pipe runs so there is no need to but pipes do cost money.

networkn

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Reply # 2132418 23-Nov-2018 09:30

The issue we have is that none of the walls except the one with the Window, is external, so we are facing ducting, no matter what. Noise is a factor, it's on the second floor, which is a factor, and having it placed so it doesn't blow right on her, or the head unit isn't on top of her, isn't really possible.

I did wonder about the effective possibility of having ducting between two rooms is? Her room backs onto our master bedroom which has a heat pump. I did wonder about "sucking" the hot air out of her room via the room, and pumping it into our room and whether that might help or not?

I suspect given that none of the consultants we have talked to over the years, has suggested it, that it's not an effective solution?

We don't mind spending the money on a heatpump, but it feels like it isn't ideal, but leaving the situation the way it is, isn't fair either.

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Reply # 2132421 23-Nov-2018 09:33

How about floor mounted?

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