Will a Mitsubishi heat pump system be efficient for winter heating?
I have a second home in East Otis, MA 01029, and plan to install a heat pump system. The home is vacant during the winter and the heat is kept at 50 degrees and have an oil hot water system for heat.
Will the heat pump system be effective in heating the main part of the house as it will be effective in cooling during the summer months? Thank you.
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You are signing an installation contract with (your expert installer) and this person is the one to include in his contract the answer to your question. Not some unknown persons on the internet..... no?
Yes.
Albert,
在气候区，您可以使用燃油液加热系统（用油燃油锅炉）或导管的Miniplit系统来加热您的房屋。任何一个系统都可以工作;这取决于你选择哪种系统。除非您的电价极高，否则导管的Miniplit系统将比燃油系统的运营较低。
The biggest challenge with a system that uses ductless miniplits is heat distribution. This approach makes the most sense in a compact two-story house with an open floor plan. If you have a single-story house that isn't very compact, the approach is more challenging.
当然，您可以始终安装几个Minipplit单位 - 例如，在客厅里，一个在走廊里，一个或多个在卧室里。这确保每个人都会感到舒适，但它提高了导管Minipplit安装的成本。
Is this a ducted Mitsubishi, or a ductless? If ductless, is it in the Hyper Heating series, designed to handle low temp operation without icing up or breaking down?
How much oil do you normally use over the winter, and which model Mitsubishi?
IIRC the lowest setpoint setting for a Mitsubishi mini-split is 60F, not 50F, but even so even if you kept it at 60F the savings at WEMCO residential-retail electric rates (~16 cents/kwh ?) would be pretty good compared to 50F using $4/gallon oil in an 85% burner.
With a 60F interior setpoint a Hyper Heating mini-split would run an average coefficient of performance of about 2.8 or maybe as high as 3.0 in that location. In rough terms, assuming it's 3, you get about 10,000BTU per kwh, and at 16 cents/kwh that's costing you abotu $16/MMBTU.
A $4 gallon of oil in an 85% burner delivers about 117,000 BTU/gallon, or about $34/MMBTU, and there is also electric pumping & standby power to account for (but we since we can't, we won't.)
So even if you're keeping it 10F warmer with the mini-split, the heating costs will be quite a bit lower.
If the mini-splits are undersized for the heat load when it's 0F or colder outside, leaving the oil-burner active and set for 50F would be more than sufficient freeze protection.
If it's your goal to get rid of the oil burner you may need to provide some resistance heat backup, with the thermostats set to a similarly low temp. As long as the mini-split is sized big enough to carry the whole load with a 60F interior temp at 25F outdoors (the mean temp in January in East Otis, according to Weatherspark.com data) the amount of resistance-heating power use won't be egregious, and it'll still come in well under the cost of heating it with oil.