[anupmathur]

Originally Posted by Thad E Ginathom

....
But just because Sharp turned out to be dud I am not put off inverter technology ....

And indeed you ought not to...
The point that was entirely missed in my contentious post is that inverter ACs use entirely different technology; yes, even for the fan motors. This is technology that is not time tested in India but has served well in Japan (and many other countries, I am sure) but is more than likely to frequently fail in India! The conditions here are so very different, both environmentally and in terms of the 'professionalism', or the complete absence of it, of service personnel recruited by the manufacturers.

As for the new gen refrigerants, they all work at far higher pressures than the old fashioned R22. This, in itself, is the cause for many of the failures. Add to that the 'greed' that is now omnipresent and we are looking at a technology that is not yet adapted for Indian conditions.
And copper coils? Copper is about the best material currently available. The corrosion is not on the 'pure' copper coils but on the 'joints' where copper has been gas welded (brazed) to the tubes of the compressor. Differential aeration corrosion; that's what it is called.

All in all, my stated position is to stay away from inverter ACs till they have matured as a technology well adapted for our conditions. Why should we offer ourselves as guinea pigs for free field trials?

[Thad E Ginathom]

i hope that it is going to be a few years before I have to make the decision again. Maybe things will have moved on.

I can't argue with your specific points. I don't know enough. Very likely you may have done your home work better than I have.

[sgiitk]

Originally Posted by anupmathur

And indeed you ought not to...
The point that was entirely missed in my contentious post is that inverter ACs use entirely different technology; yes, even for the fan motors. ....

As for the new gen refrigerants, they all work at far higher pressures than the old fashioned R22. This, in itself, is the cause for many of the failures. Add to that the 'greed' that is now omnipresent and we are looking at a technology that is not yet adapted for Indian conditions.

Fan motors in Inverter and high star rated window units is the same - bldc, I think. My 5* Hitachi also had a motor burn out.

Yes, R401a (and R32) works at far higher pressures, but R22 is a dying horse. I am not sure whether R22 will be available in even five years. R401 has been in use in the west for about a decade.

[Mortis]

Originally Posted by Thad E Ginathom

Lousy machines, lousy buy. Thank god I only bought one!

But just because Sharp turned out to be dud I am not put off inverter technology etc. Even alternative materials for heat exchangers is interesting and exiting. Copper corrodes! It was copper components that required repair in my Sharp. (apart from the motor bearings)

My locally repaired Sharp, by the way, is a little noisy, expecially compared to its luxury silence on auto fan speed when new, but it is nothing that can't be slept with, so 4K for last year's AMC was a money-wasting scam but 1.7k for this repair looks like money well spent.

Copper corrodes but it can be welded and repaired unlike the aluminium bits. Most of newer mostly inverter ACs have the 'superior' Aluminium microchannel condensors which, once they fail have to be replaced for a pretty penny along with the expensive R410 gas.

The reason im not too happy with the invertor Acs is the way they cool, especially when the weather is relatively pleasant. While Invertor ACs do not cut off in the traditional way and supposedly emit cooled air at the set temperature constantly, they do tend to kind of go into a low power/cooling state once the room has cooled to the set temperature. This state tends to last quite a bit longer than the normal cut off period of non inverter ACs, especially since we dont set ours at the lowest temp (16*C, we set to 22*C) so at times during summer it can get a bit uncomfortable and during monsoon/winter when we want it to be just a bit cooler than ambient temps, it goes into this mode quicker and for longer.
While this isnt terribly inconvenient we end up lowering the temps to get it cooling again.

[Thad E Ginathom]

Originally Posted by Mortis

Copper corrodes but it can be welded and repaired unlike the aluminium bits. Most of newer mostly inverter ACs have the 'superior' Aluminium microchannel condensors which, once they fail have to be replaced for a pretty penny along with the expensive R410 gas.

Nitpicking, but copper is actually brazed, rather than welded. This is soldering, albeit with a gas torch at red-hot temperatures. Pretty much the same as I did as hobby jeweller a long time back. (Wish I still had my torch!)

The rest is a whole set of complex questions and answers, and probably lots of greys rather than black and white. From what I remember, Aluminium is essentially less likely to corrode, but there are environments in which copper does fare better. I also recall reading that there are resin-based fixes for aluminium-heat exchanger parts. Don't underestimate "glue!" remember that, even with wood, a good glued joint is stronger than the wood itself.

The reason im not too happy with the invertor Acs is the way they cool, especially when the weather is relatively pleasant. While Invertor ACs do not cut off in the traditional way and supposedly emit cooled air at the set temperature constantly, they do tend to kind of go into a low power/cooling state once the room has cooled to the set temperature. This state tends to last quite a bit longer than the normal cut off period of non inverter ACs, especially since we dont set ours at the lowest temp (16*C, we set to 22*C) so at times during summer it can get a bit uncomfortable and during monsoon/winter when we want it to be just a bit cooler than ambient temps, it goes into this mode quicker and for longer.
While this isnt terribly inconvenient we end up lowering the temps to get it cooling again.

This must be a matter of personal taste. Maybe you just like those temperature dips that non-inverter ACs give. No right or wrong: if that is what you like, it is what you like... and what you should buy!

My standpoint is the exact opposite, and my reason for being an inverter fanboy is even temperature and humidity levels. No humidity peaks, no temperature peaks and lows. That what suits me. Our bedroom inverter AC is set to 25 or 26.

[Guite]

Originally Posted by Thad E Ginathom

My standpoint is the exact opposite, and my reason for being an inverter fanboy is even temperature and humidity levels. No humidity peaks, no temperature peaks and lows. That what suits me. Our bedroom inverter AC is set to 25 or 26.

That's the thing I like about inverter AC. Previously I used to wake up in the middle of the night cold but damp with old sweat. Not anymore ever since I used inverter AC. Whether it last long or not, time will tell. I don't worry about that right now. I will cross the bridge when I get there.

[anupmathur]

Originally Posted by Thad E Ginathom

...(Wish I still had my torch!)
....

Ha ha, a bit OT here, but do look at AliExpress. Torches for as little as Rs. 400/-! I got myself one just recently.

[Thad E Ginathom]

Originally Posted by anupmathur

Ha ha, a bit OT here ...

I had a Sievert torch something like this one, with heads for three different flame sizes.

So useful for all sorts of stuff even away from the jewellery bench. I even used it to light the open coal fire in my living room!

At a glance only, I think our AC engineers are using gas/oxygen: two cylinders, two taps on the torch.

[anupmathur]

Originally Posted by Thad E Ginathom

....
At a glance only, I think our AC engineers are using gas/oxygen: two cylinders, two taps on the torch.

My AC technician uses a butane can/bottle with a simple torch that works very well for brazing the compressor liquid and gas tubes.
https://www.aliexpress.com/item/920-...999.280.B8SQbm

[sgiitk]

@anupmathur; Yes, my chaps used an LPG cylinder with no oxygen bottle. I have a pencil torch which runs on Lighter Gas (ie same as LPG) and they claim a flame temperature of 1300C. Now copper melts at 1085C and brazing is done around 700C so LPG alone should suffice.

[Thad E Ginathom]

Could melt gold, silver, copper with my torch ---all too easily, and sometimes accidentally .

Started out with the lighter-gas-can type of torch. Using the Sievert was a real upgrade of experience, in heat delivery, controllability and, when wanted, shear power. I wonder now if it was propane or butane. But, you can see from the price in the example I posted, it is not a tool that one would buy in the first week or two of a hobby!

I never mastered the knack of using a traditional mouth blow pipe. It's like the learning to play an endless note on a wind instrument!

[anupmathur]

Originally Posted by Thad E Ginathom

Could melt gold, silver, copper with my torch ---all too easily, and sometimes accidentally .
...

Honest?! Gold and silver?
I have yet to try this. But I do suspect that gold and silver cannot be managed so easily. Copper, yes. Alloyed gold or silver, yes.

[Thad E Ginathom]

Yes, honest. And it is very depressing when something you've worked on for several hours turns into a blob!

Silver melts at a relatively low temperature. When you have several joints to make on the same piece, you use solders of different melting points. The highest is also needed for anything that goes for enamelling: the melting point of glass is above the "lower-" temperature silver solders. Remember: even the lowest-temperature silver solder means red-hot metal. It's going to go really shiny red, almost orange/yellow in an enamelling kiln, and melting is not much beyond that. The melting point of "enamelling-grade" silver solder is very close to that of sterling (.925) silver itself.

One is very attentive to the colour of the metal while heating it up. I used to keep a dim bulb and low light in the workshop, with an anglepoise brighter light close to the work, turning that off to solder. It is great fun. And a real pro told me, one day, she'd never lost the feeling of magic as she sees the solder melt and flow into the join.

Useful melting-point information.

We haven't really strayed that far from the topic. Now I come to think of it, I'm not sure: are these copper AC components brazed (at red heat) or soldered like British copper plumbing, with lead [-free these days?] solders?

[Mortis]

Hehe at work we use LPG + oxygen for casting Nickel Chrome alloys for our Dental crowns and bridges. we also have the smaller lighter fluid torches for wax work. I bought one for the house to make creme brulee and for whatever else, added to my tool kit.

[Thad E Ginathom]

Sadly, I never thought of making creme brule back then.
Oh dear, now we really have strayed from AC machines! But the lighter-fuel torches around when I was doing this stuff were spluttery and probably not as good as the ones now sold for chefs.

But... I guess what I really liked about the Sievert was that it made me feel like a pro . That, and being attached to a gas cylinder that didn't run out every week.