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Evaporative Cooler vs Mini-split

I'm in the planning stages of a remodel and need to make a decision about cooling.

I'm in zone 5B (cold, dry Denver), but the summers can get pretty toasty with a few days of 100+ and long stretches of 90+ temperatures each year. I currently have an evaporative cooler that can keep the house in the uppers 70's on the worst days and usually cool it down pretty well at night. When the air is a little more humid, it is obviously less effective, and during forest fires when the air is bad it's not really usable. My contractor would like to swap the existing, and somewhat old unit for a new higher efficiency model like a BreezeAir. I ran a BEopt model that auto-calced a cooling capacity of 1.7 tons (garbage in/garbage out, but the model agrees within 10% of my actual heating costs, so hopefully it's not too far off).

The house is about 2000 sqft, on 2 floors with a fair amount of unobstructed southwest facing glass. As part of the remodel the walls and cathedral ceiling will be insulated and any new west facing windows will be triple-paned low SHG glazing. I have hot-water baseboard heat, so there aren't any ducts.

The new evaporative cooler is about $3500. It seems like a ductless mini-split could also deliver the same cooling and keep the humidity down on muggy days while being somewhat more expensive.

So if you have to choose, which way would you go and why?

Thanks
Eric

Asked by Eric West
Posted Mon, 07/21/2014 - 18:59

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3 Answers

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Eric,
The ductless minisplit will cost more to operate than an evaporative cooler.

It sounds like your current system works well (with low energy bills) except when there are forest fires.

I have no idea how often you have forest fires, or whether you feel that it's important to pay higher energy bills for most of the summer just to be ready for those forest-fire days. If you want to solve the problem for those forest-fire days, you should install the minisplit.

Answered by Martin Holladay, GBA Advisor
Posted Tue, 07/22/2014 - 04:31

2.
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1.7 tons seems optimistic, you will probably need more especially with older southwest facing windows. Another challenge will be distributing air throughout a 2000 sq ft house. Uncomfortable hot spots are likely. Have a good AC company look at it first.

Answered by rjp :
Posted Tue, 07/22/2014 - 12:26

3.
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If the hot water baseboards are running off a propane or heating oil boiler, it's worth the upcharge in summertime cooling costs and up-front costs to install a pretty good heating/cooling mini-split, (or two) which can offset a large chunk of the heating bill a huge discount.

If the boiler fuel is natural gas it may still be worthwhile, but it depends on your current & future all-in electricity & gas rates.

Exterior roll down shades over the SW facing windows will probably be cost-effective, and provide substantial relief from the PM solar gain that drives your peak cooling load numbers.

Answered by Dana Dorsett
Posted Tue, 07/22/2014 - 16:09

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