Heating a house with reversible aircon system

We’ve put in an offer on a property that has a reversible aircon system installed. It has vents you can open or close depending on whether or not you want a room heated. It has a Mitsubishi aircon unit and lots of big flexible pipes running from the attic to the different rooms, and thermostats in the bedrooms plus a main temperature control (if I remember correctly!)

Has anyone experienced this type of central heating/cooling? Is it efficient? Is it expensive to run? Thanks!

We use reversible aircon for heating. We have two units outside, each with two compressors, which drive units in the bedrooms, salon and kitchen. It works fine. When we lived in Dubai we had a centralised aircon system as you describe (no heating required :blush:) The difference I guess is that with your system the heat pump is working whether you are heating one room or the whole house. With my current system one, two three or four compressors can be working depending on the load. I suspect that’s a more economical approach.

Do the thermostats control the vents or the main unit?

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We have that system and have been pleased with it but I have bought some heavy duty curtains to mask a veranda with an ever open door for the dogs, from the rest of the house to keep the air to air systems from working all the time.
Cheaper than heating the house with the previous wood burner.

Really good in summer heat as well.

I would also pay close attention to how much and how well insulation has been installed as that point holds the answer to your question.

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We’ve got four units, but seldom use them for heating since we’ve installed a poelle that feeds warm air throughout the house (we do use the dehumifier function in summer as it’s more comfortable than a/c). My only reservation about their heating effectiveness is that it diminishes once the outside temp falls below 0°C and if it gets down to -10° they’re no longer much use.


That depends on the units designed working temperature, yes it is reducing as temp reduces but I was in Sweden and their units were still working well because they were for a cold climate.

be interested in the Swedish units… often -15c or worse… so we’ve not considered the system.

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Wish I had taken photos but the web will probably provide. Daikin make excellent units and have a range for many different environments.

Thanks John. It sounds like it would make sense to have 2 heat pumps, 1 for bedrooms, one for living areas. We’ll have to investigate what’s possible once we’ve bought the house. I’m pleased to hear that you’re happy with your system though. I wasn’t sure how effective or expensive it might be to run.

Thanks David, it’s good to know that you’re happy with your system. It’s something new to us and we weren’t sure how efficient or expensive it might be. At least we won’t have radiators taking up wall space like we do now!

I believe they control the individual vents - so you can have a cooler bedroom and a warmer living room. Don’t know the details yet till we meet the owner.

Yes, but it is important to avoid them trying to heat areas beyond their design or capability, otherwise they blast away your money. That was a mistake we made with the first one and so we bought a 2nd unit this year for the kitchen. This means that the door between that and the living room can be left open as between them they equalise the 2 rooms. They are completely separate units though, each with its own outside fan in different places and own controls. High up on the wall, directing heat downwards, then to rise naturally, they are not in the way at all.

Ours is a very small house with no upper story. Bathroom and one bedroom are off the kitchen and, with both doors open that unit warms them both. The other bedroom is off the living room but, as it is desired to keep that cool (and flyless :slightly_smiling_face:) its door is always closed. The veranda at the back which is connected to both main rooms has a patio door always open enough for the dogs and a heavy curtain acting as a dogflap. Nevertheless this is a weak point in the system so we keep the doors connecting it to the living room closed and the doorless opening between it and the kitchen is today to be fitted with its own heavy curtain. Thus the dogs have access to all areas but the heaters are only heating what they are supposed to. :slightly_smiling_face:

We have a Daiken system that sounds very like yours, heating and cooling a 150 sq m flat in the Pyrenees Orientale. There is a exchange unit outside, and a further one in the attic, from which the big pipes go to the separate rooms (living room, and three bedrooms) I believe the thermostats control the hot air to the individual pipes, ie work on the exchange unit in the attic. Works fine, no noise, costs about 1000 euro per year, though I get the impression it costs more to cool than to heat. Our temperature range is -5 to 30, average about 15.

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Easy to forget about level of insulation.

I would like to ask here - the replies have all been supposing that the system the OP describes is, in fact, based on an air-source heat pump. Is it not possible that it is a straighforward electric heating/cooling system (depending on its age?) I am (obviously) not an expert in this but I was bothered that an assumption was being made by all thehelpful people replying and it was possible that the assumption wasn’t correct?

The size and look of the units should give it away and std electric heating wouldn’t require an external unit where the compressor usually hides.

may I ask what form of Poelle and how the warm air is distributed? I am trying to pin down how best to do something similar…

There wasn’t any mention that I noticed of an external unit, so that was why I was asking the question!

Fair point.