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I'm considering buying a new split unit air conditioner for my home. Actually, this will be for a room that is planned as a short-term rental. I'm located in Bombay, India, now referred to as Mumbai.

One question I am facing is whether an inverter or a regular air-conditioner is a better choice. I was told by one dealer that inverter air-conditioners can be problematic choices, especially in humid climates near the sea. This pretty much describes my home, which is less than a kilometer from the shores of the Arabian Sea. I checked this out on the web a bit. While I did not find much information, I did find some supporting evidence. Notably, Daikin Inverter AC Unit Fail - Moisture / Salts Damage to PCB.

Basically, the issue is that an inverter is rather more complex electronically than a regular air-conditioner, because it is doing more. This manifests itself in more complex circuitry and more circuit boards. These are referred to here as PCBs (presumably Printed Circuit boards), Given salty damp air, these circuits corrode over time. And in an inverter, there are more of these circuits. And they apparently cost more to repair. The bottom line, then, is that if you are near the sea, don't use an inverter, because you will have more frequent breakdowns and higher maintenance costs.

What is puzzling is, if this is true, why isn't there more discussion about this on the net? And other dealers I asked disagreed about this.

I'll also mention parenthetically that I have tentatively settled on Mitsubishi Heavy Industries machines. This is not directly relevant to this question, so I'll leave out the details of that - it is specific to my specific buying environment. One dealer I talked to said the PCBs in MHI machines were silicone-coated, so it wasn't an issue. I'm sceptical.

UPDATE/ADDENDUM: I eventually bought a normal A/C for the rental mentioned above. But now I'm considering buying an A/C for my own room. The difference here is that I run the A/C in my own room most of the time, so maybe it would make sense to buy an inverter for it even if it doesn't last as long as a regular A/C. Thoughts?

  • If the board has a WR coating it would be better but inverter based units do fail more often because of the additional electronics. However it won't be long in some locations and inverter based may be required for energy savings. – Ed Beal Nov 22 '17 at 14:31
  • Hi @EdBeal, thank you for your comment. But I don't understand what you mean by "However it won't be long in some locations". Can you expand on what you mean by this? – Faheem Mitha Nov 22 '17 at 15:21
  • Some regions are mandating energy efficiency. The inverter driven units do save on operating cost. One example of this in the U.S. is water heaters they are mandated by code now, some local jurisdictions require higher rated AC units already. You may want to check local requirements just to make sure. But the weather resistant coatings is a must for me (west coast USA). Hope this cleared up the comment. – Ed Beal Nov 22 '17 at 15:42
  • Thanks @EdBeal. Would you consider writing an answer? I don't think India has any rules about what kind of A/C unit to use, and if it did, people would ignore it. Anyway, my main concern is about the tradeoffs here - more failures vs enhanced efficiency. I do currently run my A/C all the time, and that looks unlikely to change, at least in the short term. So maybe a more efficient A/C would make sense. I see I haven't mentioned that in the question - I'll add it now. – Faheem Mitha Nov 22 '17 at 20:29
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I'm in Michigan and we get harsh winters and salt our roads. Salty roads and ice get on our cars, and this combination is really harsh on our metal parts of our cars. Salty humidity is also very harsh on any metal parts, even galvanized steel. Now galvanized steel in the US has improved in the past 20 years, but it is not impervious to salt water.

That said, you will need to have all important parts coated some how to prevent corrosion as salty humidity is super corrosive. There is a service in the US that coats cell phones with a nano coating. They don't even take apart the cell phone. After the phone is processed you can drop it in a pool and it will still work. The phone is guaranteed for life vs moisture and water. Liquipel.

If the AC company has this service available they can coat their PCB boards and that should help a lot. Or they can use another coating on the PCB boards. The coating cannot conduct electricity or it will short out the boards.

  • Hi Bulrush, as I wrote in my answer, "One dealer I talked to said the PCBs in MHI machines were silicone-coated, so it wasn't an issue. I'm sceptical." He then showed me a sample circuit board coated with said silicone coating. It was visibly shiny. Would this in itself suffice to protect the machine's electronics, assuming the machine's electronics are not waterproof, which I am reasonably sure is the case? In any case, wouldn't this coating eventually wear out? It must be very thin. – Faheem Mitha Mar 27 '15 at 14:31
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Copied to an answer as requested. If the board has a WR coating it would be better but inverter based units do fail more often because of the additional electronics. However it won't be long in some locations and inverter based may be required for energy savings. Some regions are mandating energy efficiency. The inverter driven units do save on operating cost. One example of this in the U.S. is water heaters they are mandated by code now, some local jurisdictions require higher rated AC units already. You may want to check local requirements just to make sure. But the weather resistant coatings is a must for me (west coast USA). Hope this cleared up the comment.

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