Quote:
Originally Posted by warmwxrules
Ok ...think i have the basics down... Now tell me this.
Why is there such a difference in SEER values between minisplit systems? What is making the difference (given they all seem to use the same refrigerant)? I look a lot on Ebay at various systems, and i see anywhere from the low teens up into the low 20s...and again...what does this even mean!? If i buy a 15 SEER (say 12K btu) vs a 21 SEER (same btu)...what am i going to see in performance/heat and cooling cost differences? Compressors, electronics, advertising hype?
Thanks...
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In the USA, all manufacturers must get their systems certified by an authority before the industry will install or insure them in permanent fashion. The two testing authorities are ashrae and ahri. They both have their own defined testing conditions for different types of systems. Heat pumps get tested different than cooling only units, packaged systems get tested different than split systems.
With cooling units, the performance indicators are seer and eer. Seer is seasonally adjusted eer, which stands for energy efficiency ratio. Eer and seer are expressed as btu per watt. The higher the number, the more efficient the unit ran during the test. A 12k btu unit that scored 12 seer averaged 1kw of energy draw during the test, where a unit that scored 24 seer during the same test only averaged 500 watts.
With heating units, the performance indicators are hspf and COP. Hspf is in the same scale as eer/seer, COP is watts out divided by watts in. The better manufacturers test their heat pumps at a variety of outdoor temperatures, down into sub-freezing territory. The lesser manufacturers test theirs only where they have to in order to get certified. As outdoor temperature drops, so does the performance.
Way back when most units ran a capillary tube and a constant displacement compressor, you could compare units against each other in terms of seer or hspf and get a good idea of which unit performed better than which during the same conditions. Nowadays, there are units that employ advanced metering devices (such as electronic expansion valves and microcomputers) and variable speed compressors that "cheat" on the tests compared to the older systems. The lesser manufacturers design their control schemes so they perform their very best within the tests. The better manufacturers design their systems to work well throughout their design range. At a glance at some charts, it would seem that a certain el cheapo unit beat a more expensive unit by a sizable margin.
It is for this reason, now more than ever, to do some homework before purchasing a new system. Some of the less expensive units perform well when you need them the most, some don't. After a few years time, when service is needed, who will want to touch your unit? How and where will you find replacement parts? These questions are as important as efficiency ratings.
Like AC HACKER said in the previous post, many ecorenovator members have had minisplit systems installed, some have DIY installation. There are a number of users that are very happy with them, and have posted their energy usage and bills to back their data.There are so many systems available, with features and functions that vary so widely, that recommending a system that works for a certain site and purpose requires research.