How many mini splits do I need in a 3 bedroom ranch in Rutland VT
We are moving to Vermont from Ohio. The home we purchased in Vermont has no AC but we’d like to have AC. I understand mini-splits are used now for A/C (and apparently heating). Our home that we are purchasing is a 1700 SF ranch home with 3 bedrooms. It has a full basement (where I’ll be building an office to work on my computer software business.) The home only has 100 amp service but I’m also wanting to install a backup generator and possibly changing to 200 amp service in order to accommodate the new mini-splits. But my main question is how many mini-split heads do I need? And can I have multiple heads and only one outside unit?
Thanks,
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With a full basement I would install a ducted mini split.
Have you really assessed your electrical needs or are you just tossing out 200 amps? I'm asking because you're talking about a generator, and trying to cover large loads is going to take a large generator.
I'm pondering a new build. Trying to design around my small [but bulletproof] generator- LoL. (I'm landlocked at 100 amp service- way too expensive to bump it up as it's an underground feed, under a roadway!)
Sizing a heat pump needs far more detail than what is provided here. https://loadcalc.net/ has a good online calculator to determine heating and cooling duties. Then you need to match that calculation to an actual unit. Yes, they do make units that match a single outdoor unit to multiple indoor heads. However, as the number of indoor heads that you need to attach goes up, so does the size of the outdoor unit that you need to buy. For many houses (particularly older ones with a less "open" floor plan), you wind up in a situation where the number of indoor heads that you need to go with a ductless approach means that you will wind up with a vastly oversized outdoor unit in terms of capacity. This becomes an issue, because heat pumps/AC's take a huge efficiency (and comfort) hit if they are frequently cycling on/off. In that case, you are likely better off going with a ducted approach (or perhaps two indoor units with a smaller duct network from each one, or maybe one ducted/one ductless).
You can go here: https://neep.org/heating-electrification/ccashp-specification-product-list to get ratings on min/max heating and cooling capacities for different models of heat pumps in different configurations. When you do your load calcs, be sure to consider a spring/fall day to compare to the minimum turndown of the selected unit.
Mitsubishi and Fujitsu are fairly popular brands. Here is the download page for the Halcyon mini-split series for Fujitsu (includes ducted and non-ducted indoor unit options). https://www.fujitsu-general.com/us/support/downloads/halcyon/ctlg.html
Good luck and hope this helps!
The home page has a blog post from Allison Bailes that is related to your question. Be sure to read it: https://www.greenbuildingadvisor.com/article/can-you-oversize-a-mini-split-heat-pump.
FWIW. You need to get a Manual J from an independent engineer. For advice on that topic, see https://www.greenbuildingadvisor.com/article/who-can-perform-my-load-calculations.