Aircons: To Invert Or Not, That Is The Question..

Air conditioning, fans, and anything related to keeping it cool, such as insulation. This would include any posts generally discussing how to keep it cool, such as which types of blocks are better insulators.... ideal wall thickness for keeping an A/C house cool, etc.

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Re: Aircons: To Invert Or Not, That Is The Question..

Postby otis-a » Sun Dec 04, 2011 12:00 pm

interestg report rr
the simulation indicates less than 5% power shift from optimum speed. Simulation work is a good 1st step in evaluation but is no subsitute for field trials and actual data.
I recall testing a high friction choke valve to minimize temperature drop. The selected vendor's CFD model predicted 56F outlet T. When trialed the outlet temperature measured 32F. Also the designed valve ports rapidly & irreversibly blinded off with black powder which passed thru a conventional choke without incident. Tis many a slip twixt cup and lip- is the ole saying.
where to park dog when in town? A barking lot... :-)))
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby Roger Ramjet » Sun Dec 04, 2011 1:48 pm

otis,
The report also raises a number of questions regarding the gases used, which is not expounded on. Do we take it they used R-744 or is it f-gases? Or was it the older CFC's that are supposed to be banned? I have seen air conditioners being bled of CFC's into the atmosphere here, so how do you find out the type of gas in your air compressor and if there is actually a "better" one that is more efficient?
It will be an interesting experiment.
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby otis-a » Sun Dec 04, 2011 2:35 pm

yepper rr
seems geo says he is up to the challenge
lets hope all goes well with his house sale!
where to park dog when in town? A barking lot... :-)))
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby Colorado » Sat Apr 14, 2012 11:11 pm

Have read through this thread as am soon to make an AC purchase and debating the inverter/not-inverter question.

I understand the advantages/disadvantages discussed above, but have a slight twist: is an inverter air conditioner going to do better than a non-inverter at handling under-voltage problems?

My understanding (which is not much) is that under-voltage, i.e., getting less than 200-or-so volts from one's nominally 230V power line, is hardest on things that have motors. I'm led to believe that under-voltage increases heat in an AC motor, thus reducing the motor's life. Not sure of the details.

For our build, we have been told by EGAT that, since we are at the very end of a single-phase power line, we can pretty much expect to have a lot of under-voltage time. I have not found an easy solution to that problem, but one voltage regulator type does exactly what an inverter-air conditioner does. By inverting the AC to DC and back to AC the voltage is back at spec. So would an inverter air-conditioner handle the lower voltage automatically? Or is it asking for trouble to have it do both the voltage conditioning job and its job for the air con?

I am not too worried about under voltage for the rest of the house, as am already likely to buy an inverter-fridge, and am pretty confident about Thai light-bulbs' ability to handle under voltage. That just leaves the fans, which are not too expensive to replace if they burn out early. (As compared to the 250,000b or so it would cost to bring in 3-phase and thus, presumably, steadier voltage.)

P.S. Regarding RR's question...

Roger Ramjet wrote:otis,
The report also raises a number of questions regarding the gases used, which is not expounded on. Do we take it they used R-744 or is it f-gases? Or was it the older CFC's that are supposed to be banned? I have seen air conditioners being bled of CFC's into the atmosphere here, so how do you find out the type of gas in your air compressor and if there is actually a "better" one that is more efficient?
It will be an interesting experiment.


Thailand signed the Montreal Protocol in 1989, which then allowed it as a 'developing country' until 1999 to stop using CFCs and other ozone damaging chemicals in new appliances. That list of chemicals is an ongoing research topic, but Thailand has since ratified every amendment to the protocol. So, with any luck, an AC or fridge made or imported in the last 12-years or so is relatively safe. I imagine the older ones have probably already leaked out their CFCs, or had them released. :roll: But hopefully the replacement refrigerant was a safer one. :|
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby Colorado » Sat Apr 14, 2012 11:18 pm

Colorado wrote:Thailand signed the Montreal Protocol in 1989, which then allowed it as a 'developing country' until 1999 to stop using CFCs and other ozone damaging chemicals in new appliances.


Sorry, just re-educated myself: Thailand only had to freeze increases in use of these chemicals in 1999, reduce by 50% by 2005, and eliminate altogether by January 1, 2010. This is what's required in the protocol, not sure if they have been ahead or behind the game in actual implementation. Any new AC should be ok. Older one..., I would guess it depends on the brand.
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby MRL » Mon Sep 17, 2012 2:07 pm

Hi all, I realize I'm digging up and old post here, but thought I'd pitch on with my 2c..

After spending lots of time researching current A/C options for my latest Thai house (the 4th one I've done here in LOS), I've amassed a reasonably broad overview on the current range of offerings..

First off, when it comes to running costs, it's all about the EER (Energy Efficiency Rating) - not about the method used to achieve it.

In Thailand, an A/C set needs to achieve an EER of 11.6 (as of 2011 rules) in order to gain a "5 Star" energy efficiency rating, so 11.6 can be considered a decent baseline.

Some of these inverter units claiming all sorts of energy efficiency gains (Daikin and Panasonic especially) are only just scraping in '5-stars' with EER's in the 12's - these expensive units can easily be bested by some of the el-cheapo "1 Baht per BTU" non-inverter units at 1/3rd the price - some of which get into the 13's..

The best of the best A/C's - Hybrid Inverters are hitting 19.5 EER - almost 70% more energy efficient than Daikin/Panasonic/Samsung/Mistubishi top-model Inverter split-system unit.

So it definitely pays to do some research and work out what the 'total cost of ownership' is going to be based on your expected usage. When doing these figures, bear in mind that A/C's lose efficiency as they age - as a rule of thumb, factor in a 4% efficiency loss for every year of age.

Also, bear in mind that energy efficiency isn't the only consideration to make - noise levels (inside and outside) should also be considered (some are terrible on this front), as should the quality of air filtration, the warranty on offer, and the cosmetics.

Not sure if I'm allowed to post any links, so will just give you some names to Google instead:

rung-ruengair - publish the EER for most of the big name brands on offer in TH. Useful for populating your next spreadsheet ;)

tnpair - follow the 'คำนวณหาบีทียู" sidebar link for a nice table of room sizes/types and the amount of BTU's required for typical Thai houses.

gaincool - excellent prices and good service (with English). When I couldn't find an answer I needed, they were always willing to help.
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby MRL » Mon Sep 17, 2012 2:13 pm

Oh yeah for those discussing refrigerants used.. up to 2010 all Thai household split system A/C's used R22. In 2011 a few brands started switching to R410a, and all new units on sale in TH must be R410a by 2015.
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby MRL » Mon Sep 17, 2012 2:26 pm

Colorado wrote:For our build, we have been told by EGAT that, since we are at the very end of a single-phase power line, we can pretty much expect to have a lot of under-voltage time. I have not found an easy solution to that problem, but one voltage regulator type does exactly what an inverter-air conditioner does. By inverting the AC to DC and back to AC the voltage is back at spec. So would an inverter air-conditioner handle the lower voltage automatically? Or is it asking for trouble to have it do both the voltage conditioning job and its job for the air con?


It's only the compressor in an Inverter A/C that uses a DC motor - the inside and outside fans are still regular 220VAC units. However, these fans are usually pretty over-engineered to deal with extreme heat, blockages etc, so, so as long as you keep your outdoor unit and inside filters clean, you shouldn't have any issues with them running on lower than normal voltages.

I also live at the far end of a bad line, and see voltage swings from 170-230 volts, so went inverter for the A/C, fridge and washing machine. For the TV's and Hi-fi equipment I use a two 1000VA voltage regulators from a Thai company called Magnet (Google them). For 9,000 Baht they keep the output voltage at a stable 220VAC through an input range of 165V-270V, and outside of this will shut everything off so no damage can occur - so far my 100K Baht TV, and 400K Baht of Hi-Fi gear have remained trouble free thanks them... touch wood ;)
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby Colorado » Sun Oct 21, 2012 7:48 pm

Thanks, MRL, for the information on inverters and low-voltage.

Although, you didn't say directly, I think I understand you correctly that an inverter compressor will do better with low-voltage than a non-inverter. Possible problem with fans noted.

I notice some refrigerators, e.g., Hitachi, advertise both inverter compressors and DC fans.

Possibly off-topic, but regarding your voltage regulators... any idea how much they push up your electric usage?

Cheers.
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby MRL » Thu Nov 15, 2012 6:07 pm

Colorado wrote:Thanks, MRL, for the information on inverters and low-voltage.

Although, you didn't say directly, I think I understand you correctly that an inverter compressor will do better with low-voltage than a non-inverter. Possible problem with fans noted.

I notice some refrigerators, e.g., Hitachi, advertise both inverter compressors and DC fans.

Possibly off-topic, but regarding your voltage regulators... any idea how much they push up your electric usage?

Cheers.


Yes - the theory is that the digital switching power supply used to convert AC into DC in these inverter units is pretty much impervious to input voltage swings. A compressor running of low input voltage AC will run hotter (more current draw) and/or suffer an efficiency loss.

The Magnet AC voltage regulators are rated at > 96% efficiency - link: http://magnet.co.th/index.php?view=product&p=24&c=9
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Re: Aircons: To Invert Or Not, That Is The Question..

Postby Makmak456 » Thu Mar 14, 2013 7:51 pm

interesting info, bookmarked !
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