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Old 01-28-18, 11:54 PM   #43
MN Renovator
Less usage=Cheaper bills
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Join Date: Nov 2010
Location: Minneapolis, MN
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wait, how much is LP for you? I thought LP has been sky high, did it take a major dip? I remember the HVAC forums recently saying that in most areas going with electric baseboards would be cheaper to run than LP, especially when you use the baseboards in separate zones and heat the occupied areas.

Personally that's what I love about the idea of using mini-split units. If I want to chill in the bedroom/office area of the house for most of the day I could just heat or cool that room and leave the rest of the house at a warmer or cooler temperature within reason, obviously not going to drop it to freezing or not run the AC enough to remove moisture to prevent mold in the basement.

The reality is in my area we have natural gas that is super cheap compared to our electricity costs and we have winters where we usually get more than 10 days that touch with a temperature under -10. BTU for BTU, the cost for electricity is 4.5 times more than from a condensing natural gas furnace. So a conventional split-system heat pump as the only heat method is considered foolish because of the defrost cycles and heat strip usage would be excessive, especially since we don't usually need a huge pile of cooling in our climate but heating BTU needs are higher in the Twin Cities, Minnesota area. My house is 2100 sq ft and needs 20,000 BTU at design conditions -13f and needs to remove 15,000 BTU at 83 degrees. A 2 ton central heat pump would probably manage at around 15f degrees here if it didn't need to defrost, but it will need to. The economic balance point here would probably be between 30 and 40f, which means that it won't be used often enough to justify the extra cost, especially with the way a natural gas or propane furnace handles defrost cycles. When a heat pump goes into defrost, the furnace will take over until the entire cycle is satisfied and then the system shuts down and the heat pump will take over for the next defrost cycle, which basically means most of the heat ends up being fossil fuel heating below 20f even if I decided to run it below the economic balance point here.

Mini-splits are better than conventional systems by a ton, but when they start to ramp up below freezing and also start needing defrost cycles, they really don't seem to compete with the cheap natural gas costs in most places. I think localized heating would be the exception and in the summer the super SEER ratings would be the true benefit.

Of course if natural gas wasn't an option here, I'd probably put mini-splits in nearly every room and plan for backup heat coming from cheap electric baseboards or something. I can't think of any other option that would be cheaper and I don't think coal or wood are good options because they generally can't be unattended and require physical work to operate.
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