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Daikin ASHP Installation Critique and upgrade suggestions

Air Source Heat Pumps (ASHPs)

Last Post by Nick G 5 years ago

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Nick G

(@nick-g)

New Member Member

Joined: 5 years ago

Posts: 3

Topic starter 11/12/2021 1:39 pm [#221]

Hi All,

Looking for the community to comment on my ashp installation that came with the house. It is certainly unconventional in these parts in central Europe but I need to make the most of it and be comfortable in the winters.

The house is a 2 story concrete block construction with some level of insulation, about 170sqm. The last energy audit rated it as E/F on a scale of A to I. Newer triple pane windows/doors throughtout.

The professional installation is a Daikin mini split system with 2 External units (5MXS90E), ~9Kwh each, connected to 5 internal floor and ceiling mounted units each. The heated refrigerant is brought in via insulated copper tubes that wrap around the facade of the house. The whole setup is about 10 years old and has been maintained. The only issue I see is that the external unit facing the constantly windy side of the house produces about 7 liters of water condensation on humid days.

We like that in addition to heating we have cooling, fan functions, air filtration as well as individual room controls and that we are not burning any gas/oil.

I understand the house previously had electric radiators so there is no possibility of in wall water pipes etc. We also have cold floors because there is no cellar, only a 1 meter crawl space above bare ground.

The system can certainly get individual rooms comfortably up to 20c but we are not quite able to get a comfortable 20c throughout the house, specially the hallways. At the moment with temps around 2-3c the Daikin system alone is using 40-50 KWH per day at a rate of 18 euro cents per KWH. And this is with 30% of the rooms closed off / unheated.

We should test with different settings but I feel that this will take us towards 70kwh per day without still being properly comfortable.

In the short term I am focusing on hunting down air leaks and keeping the heat settings more constant (based on what I read on this forum) and keeping the pump working at a steady pace vs. up and down. I plan to get a thermal imager to find cold spots.

In the long term I plan to redo the roof and insulate it much better as well as install solar panels to take the pressure of the heating costs. Insulating the house further on the facade with hard foam insulation could also be an option. Another idea if necessary is a pellet oven to supplement the heating.

So what do you suggest for improvements? Is it time for new more efficient or larger units outside, should I replace/re-insulate the external copper tubes or do something else. Would welcome any ideas!

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Derek M

(@derek-m)

Illustrious Member Member

Joined: 5 years ago

Posts: 4425

11/12/2021 1:57 pm

Hi Nick,

I would suggest that you initially concentrate on insulation and draft proofing, since if you don't need the energy in the first place, it is a win for both you and the environment.

👍

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Kev M

(@kev-m)

Noble Member Member

Joined: 5 years ago

Posts: 1276

11/12/2021 2:22 pm

Hi Nick and welcome to the forum. Most people here have wet central heating systems but I think one or two have similar to you. Have you done a heat loss calculation on your house and compared it to the output of your heating system? It would be useful to know how well the system matches the house.

What sort of floor do you have? From what you describe it's some sort of suspended concrete? Could you stick some insulation on the underside? I have a block and beam concrete floor and I have a layer of insulation on top. So it's ground/800mm gap/concrete block/insulation/chipboard/wood or tile. You can lose a lot of heat through an uninsulated floor.

A lot of folks on here have wood burners to help the ASHP when it's really cold.

How do you heat your water? Electricity?

Kev

👍

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Nick G

(@nick-g)

New Member Member

Joined: 5 years ago

Posts: 3

Topic starter 11/12/2021 3:15 pm

Thanks Derek and Kev.

I will lookup the documents I have on heat efficiency calculations. I believe I can also contact the energy assessor or perhaps the installer for more information. In any case I will read up on heat loss calculations.

The ground floor is suspended concrete spanning the footings of the house. On top of the concrete we have a few cm's of screed and then tile and wood floors. We found some insulation when changing tiles however it did not look too intact and of insulation value. The cold floors confirm that. The idea for insulation from the underside sounds good. I can look for someone up to the job.

For hot water we have a 100 liter electric water heater with a C energy rating and annual usage of 2600KW per the label. Left on the eco 50c setting full time. We have thought about switching our baths and kitchen to instant heaters as we found this arrangement fairly efficient cost and space wise in our previous place. Showers aside, by the time the warm water arrives we are finished with the tap!

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