More heatpump placement confusion

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Gemini

429 posts

Ultimate Geek

#243523 16-Dec-2018 10:00

I've had two installers around, neither gave a firm recommendation or clear advice on where to place indoor or outdoor units.
The ceilings are angled and the high point is in the middle of the house so connecting an outdoor unit to a high wall indoor unit at the highest point is not easy. We want cooling so a floor unit is out.
For the bedroom, which is in the middle of the house, high wall indoor would mean interior visible piping to a roof mounted outdoor unit attached to a wood wall. The roof is a split design. Apart from the asthetics, I'm concerned about tradespeople walking on my decramastic tile roof and vibrations from the outdoor unit.
The installers didn't seem too fussed where things went so I'm wondering how important optimal placement is now?

RunningMan

8961 posts

Uber Geek

#2146013 16-Dec-2018 10:10

Have had installers want to roof mount external units before on a decramastic tile roof in a valley. Like you, was concerned about noise and vibration transmission, so went with a quote that installed the external unit at ground level on a concrete slab. Easier for maintenance, and less exposed to the elements too. Particularly with a bedroom, noise is probably more of an issue as well.

The two factors as I understand it are the length of the refrigerant lines between the units, and the vertical height difference - you should be able to get specs for the units you are considering, and see if you can get a creative way to get the lines from one unit to the other.

Gemini

429 posts

Ultimate Geek

#2146062 16-Dec-2018 11:25

Thanks, I've checked those and they will not be a problem for the units I'm looking at
Depending on kw
20m-30m max pipe distance
15-20m max height difference
So optimal placement of units is possible, it's just the installers don't seem too fussed about that ...

timmmay

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#2146087 16-Dec-2018 12:31

I was in a house with the outdoor units bolted to the outside once. The whole house vibrated, it was awful.

Why is a floor unit out? Yes cooler air falls, but they must be able to direct the air upwards?

If I was putting in air conditioning now I'd put in a multi room unit, summers seem to be getting hotter.

Batman

Mad Scientist
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#2146096 16-Dec-2018 12:51

How much heat./efficiency do you lose per metre pipe length?
Maybe run the pipe longer for best placement of both bits?

Aredwood

3885 posts

Uber Geek

#2146101 16-Dec-2018 13:00

Can you run the pipework through a wardrobe, cupboard, kitchen pantry etc? Definitely try to have the outdoor unit on the ground outside if you can.

Also with height differences, often there is a strict restriction on placing the outdoor unit higher than the indoor unit.

Aredwood

3885 posts

Uber Geek

#2146113 16-Dec-2018 14:00

Gemini: So I noticed the super efficient 7 energy star Daiken US7 has 50% shorter max pipe length and level distance than other models
Does this imply pipe length has a big impact on efficiency?

Since that system uses R32, which is a mildly flammable refrigerant. There is a restriction on room size Vs amount of refrigerant in the unit. So that if the indoor unit starts leaking, the refrigerant mixed with air in the room won't be enough for it to be able to catch on fire or explode.

Or maybe Daikin are simply worried about oil return to the compressor.

You could always add more insulation to the pipes if you are worried about heat gain or loss from them. Also depends partly on where the pipes are installed. As pipes running inside the house would simply indirectly heat or cool the house from their losses.

Gemini

429 posts

Ultimate Geek

#2146114 16-Dec-2018 14:06

If indoor placement at the highest point of an angled ceiling is not so important I can run two indoor units off a single outdoor with shorter and more discret piping than the better indoor location would allow
Trying to decide which is better

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Kickinbac

427 posts

Ultimate Geek

#2149605 23-Dec-2018 13:21

Aredwood:
Gemini: So I noticed the super efficient 7 energy star Daiken US7 has 50% shorter max pipe length and level distance than other models
Does this imply pipe length has a big impact on efficiency?

Since that system uses R32, which is a mildly flammable refrigerant. There is a restriction on room size Vs amount of refrigerant in the unit. So that if the indoor unit starts leaking, the refrigerant mixed with air in the room won't be enough for it to be able to catch on fire or explode.

Or maybe Daikin are simply worried about oil return to the compressor.

You could always add more insulation to the pipes if you are worried about heat gain or loss from them. Also depends partly on where the pipes are installed. As pipes running inside the house would simply indirectly heat or cool the house from their losses.

The US7 has a additonal pipe for air that is limited to 10 metres. It’s 50mm diameter and linked to a fan on the top of the outdoor unit that provides outside air to the indoor unit. Suspect they limit the refrigerant pipe run to cover that. Plus longer refrigerant pipe runs reduce efficiency. In the heat pump engineering data manuals, which is not usually available to the public, there are tables to calculate the efficiency at the various pipe lengths.

MadEngineer

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#2149642 23-Dec-2018 15:19

We have a floor console and it cools perfectly well. Better than a wall unit imho purely based on the fan size and ultra low speed it rotates at once the room is at the desired temperature.

You're not on Atlantis anymore, Duncan Idaho.

Gemini

429 posts

Ultimate Geek

#2150606 26-Dec-2018 06:43

I'm going to get another installer around to help decide where the indoor unit should ideally go. Heatpumpguys.co.nz. Anyone used them?

Gemini

429 posts

Ultimate Geek

#2159618 12-Jan-2019 11:31

Had a third installer in. He seemed keen on a close to optimal placement for airflow for the indoor unit. The optimal placement uses the same outdoor unit location and pipe length but the pipe routing would be a bit more complicated.
It's not the best indoor placement aesthectically either but now most houses have heatpumps it prolly doesn't matter?
Unlike the previous installer, he wasn't keen on mounting the outdoor unit on brackets near the top of the exterior wall but not for the reason of vibrations, instead he was concerned about exposing the outdoor unit to salt spray.