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Sanity Check: Mini-Split Power Consumption
Hey all. We put in mini-splits about a year ago, and we're hoping to use the system for basically all our heating this winter in the Boston area.
We run our house on 250-300 watts typically (assuming HVAC is off), and we're seeing comparatively huge energy consumption heating kicked in. It might just be my unfamiliarity with enormous electricity bills, but it would be good to get a sense if what we're seeing is normal, or if there's something up.
On a reasonably cold day (43F high, 22F low, 30F average) last week, we used 98 kWh, contrasted with 10-13 kWh during a temperate week in September. At times on the cold night, the house was drawing over 4kW, which is just way different from what I'm used to – when I turned off the system for a moment, it went right back below 300W. Right now, it's 52F out, and the house has been hovering around 2.1-2.2kW.
It's a 1920s house (3 stories, 2300sqft) with original windows. We got things better insulated last year in the attic and blew insulation into the exterior walls, but I can't imagine anyone could use the word "tight".
System 1 –
Condenser: Mitsubishi MXZ3C24NAHZ2 (24K BTU)
Head 1: MSZFH09NA (9K BTU)
Head 2: MFZKJ12NAU1 (12K BTU)
Head 3: MSZFH06NA (6K BTU) - Currently off (guest room)
System 2 –
Condenser: Mitsubishi MXZ3C30NAHZ2 (30K BTU)
Head 1: MSZFH12NA (12K BTU)
Head 2: MSZFH06NA (6K BTU)
Head 3: MSZFH12NA (12K BTU) - Currently off (attic)
What's the best way to know if this looks roughly sane/expected? I don't necessarily need anything exact, just need to know that there's nothing terribly wrong, and that I'm getting approximately the efficiency I should expect from decent mini-split heat pumps.