What’s the best wall height for a ductless mini split heat pump?
Hello out there,
I’ve been heating my home with a Mitsubishi Hyper Heat FE-18 heat pump for over a year now and learned a valuable lesson about which wall to place the unit on. I “hid” it on a partition wall, 90 degrees to an exterior wall, and place it up over a wide opening (8 to 9 ft. opening) from the LR to the DR. I thought the air circulation would be fine with the vanes pointing straight down supplying hot air to both the LR and the DR. I learned that the vanes do not go in a straight vertical position, they are always angled a little, understandably (now) so heat isn’t being forcing directly down a wall. However, last winter there were some problems with the vanes not returning to a down position after the unit went into its defrost cycle for which the vanes moves to a horizontal position. The end result was a DR with warm air pooled at ceiling level and not very good circulation of the heat. If I moved to the other side of the doorway into the LR, the temperature dropped dramatically just a few feet from the warm room.
So this year, I’m about to have the unit relocated to the exterior wall in the LR, near the partition wall/opening to DR. It is pretty pricey to have it done so I want to make sure I get it right this time. I feel pretty confident about the location, but not sure what to do about the HEIGHT. I rarely use the AC; it’s the heating that I’m concerned about. It seems that placing the unit only inches from the ceiling (which is what the HVAC guy says is where they should be installed), is asking for the heat to stay in the top portion of the room. An apartment I lived in had a Monitor floor model hot air space heater and it did a terrific job. I also remember an article by Marc Rosenbaum saying that he had a heat pump and had a similar problem and would recommend putting them lower on the wall. Can anyone point me to that article? Or has anyone had experience mounting these units lower on the wall?. Any info base on first hand experience would be most helpful. The relocation is coming up soon. Thank you!
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Replies
Theresa,
Here is a link to the last Q&A thread where this issue was discussed:
Minisplit blowers mounted low or high?
Martin, thank you for directing me to the thread and to Talmage's article. There doesn't seem to be much first hand information out there. I need to make a decision by this Monday and it's hard to base a decision on one article and a few theoretical comments. It would like to hear from anyone who has actually mounted a unit lower on the wall or knows of any statistics to indicate what's more advantageous for heating.
Thanks! Great to have this forum.
Theresa,
Good luck with your decision.
It's safe to say that most ductless minisplit units are mounted near the ceiling. As far as I know, that's how the manufacturers recommend that these units be installed. (This can be easily verified by telephoning one of the manufacturers and asking for someone on their technical help line.) The manufacturers have designed these units so that the air flowing out of the units gets good distribution when they are mounted high on a wall.
Talmage's approach is unusual. That doesn't mean he's wrong -- just unusual.
They should be mounted higher on the wall, as to take into account some "throw" into the conditioned space by the conditioned air/heat/cool. The other alternative is to box the unit in closet w/ a LARGE return air grill and use a fan powered ventilation system to put the conditioned air (under pressure) via duct work, to where ever you want it. This approach may also take a externally wire thermostat/heat sensor.
Martin, thanks for the quick reply and your comments. In the interim, I had a conversation with Peter and was convinced that mounting the unit low on the wall was the way to go. It makes complete sense to me, theoretically. I have also spoken to manufacturers who do recommend mounting them high - but haven't gotten a good rationale from them. Maybe I need to get that in order to decide. Is that a hold-over from when they were AC units? Is it because they are a bulkier design (i.e. bulkier than floor models) and get in the way when they're lower? Installation today was just cancelled due to weather so I have a reprieve to think about it for a few more days, If anyone has mounted the unit low on the wall and is not happy with the results, I would love to hear from you.
I have installed several of mini split systems (https://qualityhomeaircare.com/best-ductless-mini-split-air-conditioners/) They are very easy to install. If you get one get a inverter one it changes the speed of compressor to use less power. If you get at least a 16 seer the heat out put is very good. They come pre charged with freon but it is best to pull a vacuum on line before opening valve to release freon. The only bad thing is the water condensation line make sure you clean it out once in a while, if it gets plugged the water comes out inside all over wall