Mini split options under $1500?
Rocky12
| Posted in Energy Efficiency and Durability on
I’m building a small guest which is ~450 square feet. I want to put a mini split in there but do not want to spend $3000 plus.
I see Pioneer brand mini splits on Amazon for around $700. I realize these probably aren’t the quality of the more expensive units HVAC companies sell you but has anyone installed one of these before? They have amazing reviews online.
Alternatively, can anyone recommend another unit that I could get for under $1500 (including installation cost from professional)?
Thanks!
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Replies
Rocky,
You might be better off installing a simple window-mounted air conditioner for cooling, and an electric resistance heater for heat.
It would only make sense to invest in more expensive equipment if your guest house is used all of the time.
You might be able to use a PTAC unit (0.6 tons, for example). Maybe Dana will comment.
My son installed a Pioneer 12KBTU for his second floor air conditioning, and supplemental heat in the winter. Mounted on an exterior wall in the main hallway at the top of the stairwell. He is very pleased with the performance and cost. Followed instructions and did it himself. He did have to buy a vacuum pump to do the installation properly, however. The heating rating on the premium units is only rated down to -5 degrees F, so would not be a reliable source of heat for the extremes of climate zones 5 or higher but might be fine for heat in zone 3 and maybe 4. Very quiet.
For intermittent use in a guest quarters the somewhat lower efficiency of a point terminal heat pump ( PTHP ) isn't a big deal. They don't modulate like a mini-split does when running, but a mini-split that spends 95% of it's time in "OFF" mode doesn't modulate either. A pretty-good half ton to 3/4 ton PTHP can be installed DIY for about a grand, all-in, for including everything from the unit itself to the wall-sleeve, exterior grill, to the breaker in the electrical panel.
Whatever you install it's important to run the heating & cooling load calculations and right-size it to the extent possible. An oversized unit would be able to bring it up / down to temperature quickly, but it's latent load handling in cooling mode would suffer.
Guys, thanks for the input. As expected, a lot of mixed advice haha.
Martin - what are the main reasons to go with a much more expensive unit, if these cheaper ones have 5-7 year warranties?
James - That's good to hear. I have heard a lot of good things about this unit for the price. I am still unsure why many people advise to stay away. Seems to do a good job and run more efficiently than regular ac/heating. Did e get any warranty at all? On their website, it says there is a 5 year warranty as long as it is "installed correctly"
Dana- I will look into these, although they are not as efficient right? Are you saying it's important to match the BTU to the correct square footage size? So I would want to stick with 10k-12k BTU? Anything higher wouldn't add any benefit?
Rocky,
I never advised you to "go with a much more expensive unit." I was the guy who advised you to install inexpensive equipment (a window-mounted air conditioner and an electric-resistance heater).
Your original goal was to purchase a ductless minisplit for $700, and then to find an HVAC contractor who was willing to install a unit that you purchased on Amazon for a labor charge of $800. I think your goal is unreasonable, which is why I recommended a different route.
The efficiency of a PTHP isn't as good as a mini-split, but they're not terrible at 25F & higher. For an intermittent use application the simplicity of installation & maintenance is usually more important than the outright efficiency. Bear in mind that some low-end mini-splits aren't significantly more efficient than a PTHP.
Sizing is always important., but the sizing needs to be relative to the design heating/cooling loads, not the square footage of conditioned space. The load per square foot ratio varies (a LOT) by construction and location. Something with 10-12,000 BTU/hr of output is probably going to be EXTREME OVERKILL for a tight IRC 2015 code-minimum 450 square foot building or addition, and would have lousier latent cooling than something more right sized, which is why I was suggesting a half-to-three-quarter ton sizing, (6000 - 9000 BTU/hr coolikng) depending on the actual load numbers. They don't make PTHPs smaller than the half ton.
Rather than "Anything higher wouldn't add any benefit?" it's worse than that. Any thing bigger provides NEGATIVE benefit, with worse latent cooling performance, more temperature cycling (in both heating & cooling modes), and if it's big enough to short cycle (could happen, depending on your actual loads), LOWER efficiency. An oversized mini-split may have a minimum modulation level greater than your design loads if you're not careful.
So, run some semi- real heating & cooling load numbers with an online Manual-J calculator (eg: http://www.loadcalc.net/ ) using aggressive rather than conservative assumptions on air tightness, etc. It's not quite as accurate as a real Manual-J software package but it'll give you a good idea. Don'tt put your thumb on the scale with outdoor design temps any worse than the 1% & 99% temperature bins:
https://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf
As lousy as rules of thumb are, a ton of cooling per 1000 square feet would be the mid-range for smaller houses/spaces in the southeastern US, and 15 BTU/hr per square feet @ 0F outdoors would be the high end of the range for tight code-min 2x6 framed houses, 20 BTU/ft @ 0F the high end for tight 2x4/R13 type construction. If your 99% outside design temp is 25-30F make that 8-10 BTU/ft-hr for 2x6 construction, 12-15 BTU/ft-hr for 2x4 construction. If this is an addition rather than a free-standing building the numbers would be even lower.
So whether it's a half-ton vs. a 3/4 ton depends on your particulars, but it's highly likely that anything over 3/4 ton would be grossly oversized.
A typical half-ton is PTHP such as the Amana PTH073Gxxx can deliver 6800 BTU/hr of cooling (at 95F) or heating (down to +25F outdoors, below which point it turns on internal resistance heat. LG's LP073HDUC or Gree's ETAC-07HP230V15A-A are pretty comparable. There are others. So using the ton-per 1000' cooling WAG you would still have margin on cooling capacity @ +95F, and it's duty cycles would be long enough to do significant latent cooling. At the 15 BTU/ft-hr @ +25F high-end WAG for heating you'd still be covered 100% .
http://www.h-mac.com/product-catalogs/amana/Amana-PTAC-Catalog.pdf
http://www.lgptac.com/ptac-heat-pump.aspx/Download?filename=SB_PTAC_208_230_HP_11_16.pdf&id=1649
http://www.greecomfort.com/wp-content/uploads/2014/06/ETAC-230v-Heat-Pump-Submittal-V2.0.pdf
I know this is an old thread but thought I'd add that at this point I'd go for a midea u shaped inverter window AC, some kind of electric space heater, and could even throw in a midea dehumidifier and a nice HEPA filter for under $1500 with no professional install needed. This is what we've been doing for the last 9 months in a ~400 square foot space within a larger building while planning what house we may eventually buy or build. A bonus is that we'll be able to easily take it all with us wherever we go.
https://www.homedepot.com/p/Midea-8-000-BTU-U-Shaped-Inverter-Window-Air-Conditioner-WiFi-9X-Quieter-Over-35-Energy-Savings-ENERGY-STAR-MOST-EFFICIENT-MAW08V1QWT/315241074
https://www.homedepot.com/p/Midea-50-Pint-Midea-CUBE-Smart-Dehumidifier-with-Pump-3X-More-Water-Capacity-ENERGY-STAR-MOST-EFFICIENT-for-up-to-4-500-sf-MAD50PS1QGR/315869075
We have a 12k btu Pioneer Diamanté series minisplit that we bought on Amazon. It heats and cools our entire 900 square ft half basement (in a 1950s raised ranch house). It works perfectly and is very quiet. It cost less than $800 on Amazon, but I had hard time trying to find someone to install it. It seems that all minisplit installers want to sell Mitsubishis :) I eventually found a crew that did it :) We also have an expensive Mitsubishi hyper heat 18k btu minisplit as our main heating and cooling unit on the main level of the house. Honestly, I regret that we did not install another Pioneer upstairs. I do not see any difference in their performance.