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i07nyc

rewiring my house and mini spit system

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i live in a house built in 1904. half the house has been rewired and half is the original bx. i'm thinking about installing 2 mini split systems somewhere in the future. i have a 100 amp box and did a load calculation which came to 52 amps not counting the 4 window a/c's im using now. my 1st floor is about 900 sq ft so it seems like i would need a 18000 btu system there. my 2nd floor is 600 sq ft so 14000 should cover that. with those 2 sized systems and my size box and house load would i have enough amp space with my current box or would i need a larger box. 

Edited by i07nyc

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Right but putting in 2 units pushes the draw around 92 amps. Seems kinda close to the 100. I can't go to a larger box without replacing everything out to the street. I have a 4 gauge feeder and was told 100 amps max. Should I trust an 8 amp window or scrap the idea and stay with window units.

Edited by i07nyc

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Power consumption for an 18k mini split will be more like 8-10 amps installed with a 20 amp breaker.

your estimating 32k btus for 1500 sq ft sounds oversized. Want to get load calculations done before you get any equipment.

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I did a very quick calc on the btu's then added a few thousand for good measure. In not gonna be adding the system for a few years. My electric is a mess though. I have to redo a good amount of it and since I do in trying to take into account future plans.

I have one circuit that has 8 outlets and 7 lights on it. The circuit covers a fridge, stove, microwave and other kitchen stuff. The breaker next to it was added in the 70's or 80's and goes to one outlet hooked to a lamp. I'm gonna try to balance that out. This setup repeats a few times in my panel.

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On my panel, The clamp on had probably 6 amps on one side and 7 amps on other. 

I added everything as 240v and it was pretty balanced even when heavier loads kicked on.

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If you just added up the load to get to 52  amps and most of that is 120v load, don't forget you will be splitting that between 2 hot legs giving you 26 amp load on each.

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