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Thread: LG Mini-Split Heatpump system - Operating temp?

  1. #1
    DIY Junior Member yds's Avatar
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    Default LG Mini-Split Heatpump system - Operating temp?

    I have an LG minisplit ductless system installed in my new third floor addition here in Toronto (outdoor unit model LMO240H; indoor units LMI090HP). The contractor who installed it said it should operate up to about -15C outside temp. We're currently at about -5C, and I'm not getting a lot of heat out of either head-unit (there are two). Should I be? What the the typical operating ranges for this (or similar) ductless heatpumps??

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    Plumber jimbo's Avatar
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    You need to look at the specs for the unit. -5C is reasonable, -15C is surely pushing the limit. When you use a heat pump in such a cold climate, it is common to have secondary electric strip heat, to "jump start" the heat in the room. The mini-splits do not have that. Under the best of circumstances, a heat pump does hot produce hot air, it produces air just several degrees warmer than the current room air. Left on long enough, it will raise room temp, but it may take a while.


    I looked at the website, did not see your model number exactly, but the newer inverter heat pumps do reference a range down to 5F, which is your
    -15C. At these low temps, you will feel just a slightly warmish breeze coming from the air handler!
    Last edited by jimbo; 12-07-2010 at 07:10 AM.

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    DIY Junior Member yds's Avatar
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    Quote Originally Posted by jimbo View Post
    You need to look at the specs for the unit.
    This is the Cdn webpage for the unit I have. Could not find the specs re: outside temps.

    http://www.lg.com/ca_en/air-conditio...it-LMO240H.jsp

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    Retired Defense Industry Engineer jadnashua's Avatar
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    My father had a heatpump system in upstate NY - the town where he lived had a local electrical co-op, and the rates were cheap by comparison. I wouldn't put that system in my home, but I guess they got used to it (would consider it if the winter temps weren't so cold, though, or the rates here were more conducive to it). I never really liked it since the air temp out of the vents was barely warm. His system did not have an easily changed fan speed, so you also had the wind chill effect since the fan was optimized for a/c, not heat. As the outside air temp drops, there's less and less heat easily available, and the output temp drops even more. Without backup heaters, there will be times during the winter in Toronto where they may not produce much of any heat.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member yds's Avatar
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    Quote Originally Posted by jadnashua View Post
    Without backup heaters, there will be times during the winter in Toronto where they may not produce much of any heat.
    We do have baseboard electrics as a backup - I knew I wasn't going to get away with going the entire winter with just the heatpump. But we're only barely below the freezing mark at this point in the season and I was hoping to get nice warm air out of the LG for a bit yet.

    As a side note, the LG wall units have a "chaos" air feature which alternates the fan speed as well as oscillating the vent direction vertically and horizontally. Works pretty well in evenly distributing the heating/cooling around each room (the two rooms we have the head units in are each only about 175sqft).

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    DIY Junior Member yds's Avatar
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    I had sent a note off to LG customer care about he operating temps. Here is their response:

    Hello, thank you for contacting LG Customer service.

    The minimum temperature the heat pump can be used is -5C using the unit any colder than this temperature can damage the unit.

    Thanks
    Dave H.
    LG Customer Service
    LG Canada


    HMMMM. Not exactly what my contractor told me, but consistent with what seemed to be happening. Just curious - how would use below the recommended temp cause damage? Would/could it burn out the compressor?

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    Retired Defense Industry Engineer jadnashua's Avatar
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    The internal logic (should) prevent it from operating when it gets that cold. Compressors are designed to compress gas to fluid...if it is really cold, the fluid may not evaporate, and it would be liquid coming back in. Can't compress liquid, and the high pressure cutout may trip. Note, I'm not a pro on this... Ideally, there should be a temperature sensor that would prevent the compressor from turning on before the point damage could occur.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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