Air conditioning

[EatenByLimestone]

I’ve been running with an 11k btu unit upstairs and a 5000btu downstairs. I finally put the 6000vtu kitchen AC in. I’ve got 1 more 5000btu I can put in if needed.

11 up and 11 down. I’d love to be able to justify a mini split, but I just can’t justify the upfront money when it’s used so little. My wife likes it warm being from Houston, I work outside so I’m used to the heat, and the kid is used to playing sports in the heat and isn’t bothered by it.

Maybe when I get to the point I can’t put window units in anymore or the wife really complains about the noise.

I find it’s much easier to justify expenses for comfort than money saved. The break even point us usually too far away.

 

[kborndale]

Get one with a heat pump for the shoulder season. Makes justification easier.

 

[bogieb]

I never had AC and this house would stay coolish (low to mid 80's) prior, but summer of 2017 I had to take down the huge willow tree on the south side. I disliked that tree, but boy did it keep the sun from baking the house until the sun hit full west (no shade on that side). So in 2018 I got a 12k portable unit for the living room .

In 2020, when I started working from home, a I added a 6k window unit in my office. That 6k unit was so loud and didn't really keep up with all the heat from two computers, 3 monitors, plus other electronics (all in a 9x9 room). When it became evident I would be WFH for at least another summer, I had a mini-split installed. I now have a 15k head in the living room and a 12k head in the office. On paper they are a bit of overkill (on paper, one 12k unit would do the trick), but my experiences led me to oversizing a bit.

Anyway, once I started WFH, then comfort became king, not ROI. Although I spent a lot less in electricity with the mini-split on the hottest summer on record, I'm pretty sure there is no way I would ever save enough to "justify" the expense if I just went by that.

I didnlt realize that the mini split will heat when I bought the system (that wasn't important to me). When I figured that out, I used it whenever I could fall/winter of 2021/2022. At that time it ran about even with pellet stove use. However, late last summer they raised electric prices by 100%, so I strictly used my pellet stoves for heat and saved the electric bill with cheaper pellets. It's always nice to have options for heat anyway.

 

[EbS-P]

I’m cooling 2000sq ft up and 1000 sq ft finished walkout basement with 22k (second stage hasn’t kicked on and adds another 11k btus) when it’s 95 outside here in the hot and humid coastal south. And a 105 pint dehumidifier. Comfort is lovely. Summers will only get longer and hotter. Use the tax credit. Should get to be point of sale next year (I think). Don’t forget humidity control. If your electric rates are higher than average consider a small 2-4kw solar array. Bigger if you think you will be getting an EV. Now if you only have 100 amp service…. Everything will get more complicated.

 

[woodgeek]

I'd say buy a KillAWatt, and see what each unit pulls in a week.

I bought one of those super efficient U-shaped window units with inverter tech from Midea, after seeing the kickstarter here like 5 years ago. I was going to use it to supplement the dehumidification in my house, but never did.

10,000 BTU U-Shaped Inverter Window Air Conditioner WiFi, 9X Quieter, ENERGY STAR Most Efficient Over 35% Savings, White

I later loaned it to my GF, who cools her 1900-vintage brick rowhome with two window units, replacing the upstairs unit that does most of the effort. She saw her summer electric bill cut in half. And saved her about $500 per season, less than the cost of the unit.

This is much better savings than I would estimate if I assumed the old AC unit was SEER = 6 or 7, as is typical for older units.

Conclusion: the old unit, that was loud as heck, had shot bearings or something, and while it worked, its SEER had dropped to a very low value.

Sometimes your legacy equipment is not as efficient as it says on the label. Alternatively, you might make a case for buying a new window unit and retiring one of your current ones if its a dog.

 

[DuaeGuttae]

Woodgeek’s post above is spot on about measuring the usage of your current units to see how much they’re pulling each week.

We own three of the Midea units he referenced above. We bought two on the Kickstarter program he mentioned. I believe ours came in the spring of 2020. One arrived with significant shipping damage, though it did work out of the box. Midea nevertheless replaced it for us, but the damaged one has continued to work which is why we have three.

One we used in my husband’s work-from-home office that lacked any HVAC. Two others we used replace or supplement central air as we could in pretty brutal Texas heat.

We have now moved to less hot but more humid Virginia, and we have all three installed in a home without central air conditioning. We use the “dry” feature from time to time but find it cools more than we need, so we tend to keep them on the auto function. My Killawatt unit is packed away somewhere, so I’m afraid I can’t run any tests on them at the moment. I remember measuring in Texas and getting some decently pleasantly low numbers there, but I can’t give any specifics.

The Midea units are a lot less noisy than the standard window air conditioner in one room here.

I wish I could find that Killawatt meter to measure the usage on my mom’s old chest freezer as I’m trying to convince her the the Energy Star upright freezer we brought with us may me more efficient than the fifty year old chest. We don’t need both, but it would be interesting to have numbers to compare.

 

[gthomas785]

It's not always just about roi payback, sometimes the added comfort is worth something as well. We used to have a window shaker in the bedroom which was loud and musty. Switched to a mini split last summer and it is so quiet and the air quality so much better. You just don't realize what you are suffering through with window units until they're gone.

Also the condensers on those are usually completely clogged with dirt, the efficiency goes down the toilet within the first couple hundred hours of run time. If you flush it out with a garden hose every season then maaaybe you can get close to the label efficiency but most are nowhere close.

 

[gthomas785]

You can also save money by DIY installing a mini split which improves the payback picture a lot. I'm not talking about the MrCool ones, the gree or midea or pioneer units you can order online in the ballpark of $1000. Even with a $500 outlay on some standard HVAC tools like gauges and a vacuum pump you will still be way ahead vs. a pro install with equipment markup.

Watch some YouTube videos- the pro channels, not the diy guy doing it for the first time. If you've ever done brake lines and know how to use a flare tool it is a piece of cake. I've installed a few of my own units so if you want to go this way I can refer you some good resources just let me know.

 

[EbS-P]

We were talking about ACs today and I asked my 9 year old what he thought a new AC would cost us. He said 60$/ month he was right on. 15 years at 60$ call it $11k. Or two Starbucks drinks a week with a 1$ tip.