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Inverted aircon


THAIPHUKET

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2 hours ago, mogandave said:

 


Generally speaking, if your unit is sized correctly, you should use 5-10% less electricity with a high quality inverter unit, over a high quality conventional unit. If you buying new unit, you should certainly consider getting a high quality inverter unit.

In any event, buy a brand that is popular, and a model that is well represented in your area and by your contractor.

I like the the cassette type that mounts in the ceiling. These are getting more popular, and are being offered by more and more manufacturers. Mounted in the center of the room, they cool in four directions, and draw the return air from the center of the ceiling. No cold or hot spots.
 

 

I don't see where you named the company that you work and wonder if you could clarify why the energy savings you state are so much lower than, for example Daikin who claims at least 30% lower energy cost?  Everyone that I know with new vs. old type of experience has it closer to my result of near 50%.  I suspect most folks don't have the equipment to test, but I do - so while not clinical testing, I'm pretty sure of my results.  So, why does your company have such a relatively small delta?

 

Oh - and if you could comment on whether the longer "pipe" runs to a center ceiling unit would have issues for such placement.  Thanks.

Edited by bankruatsteve
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Must confess when I have stayed at other places the constant click of turning on and off drove me up the wall...My Daikin inverter is now ten years old, no clicking on and off, yes you can hear the fan but l have it on high, on low it is very quiet...You are never going to get a totally quiet fan, any type of fan....

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I don't see where you named the company that you work and wonder if you could clarify why the energy savings you state are so much lower than, for example Daikin who claims at least 30% lower energy cost?  Everyone that I know with new vs. old type of experience has it closer to my result of near 50%.  I suspect most folks don't have the equipment to test, but I do - so while not clinical testing, I'm pretty sure of my results.  So, why does your company have such a relatively small delta?
 
Oh - and if you could comment on whether the longer "pipe" runs to a center ceiling unit would have issues for such placement.  Thanks.


I didn't say where I work, neither did I comment on your findings, but to be clear, if inverter air conditioners routinely saved 30% of energy costs, every commercial building in the US would be converted in the next six months, and conventional units would be outlawed inside of 5 years.

Aside from cleaning the filter, no issues with the ceiling mount in the 4-5 years it's been installed.

The height of the unit makes changing the filter a little more difficult, but it is well worth it IMO. Nice and cool, without the wind, and without having to lay the room out around the AC placement.

Daiken builds a nice cassette unit.


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How high should the ceiling be? Can the stream be modified so it blows more in one direction? The reason for my question is, we have a fireplace which makes the positioning difficult.

Sent from my HTC One using Tapatalk




They only protrude about 20-50mm, so the ceiling height is not critical, but it is critical that you have space between the ceiling and the next floor or roof. Different models and brands take more or less space.

Some brands or models can be set to 1, 2, 3 or 4 sides.
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2 hours ago, mogandave said:

but to be clear, if inverter air conditioners routinely saved 30% of energy costs,

then the blatant lies spread by marketing people would be plain truth.  :laugh:

 

the emphasis is of course on "routinely" because under certain conditions an inverter unit can indeed save 30% energy. but only technical ignorants believe that these conditions are constant and apply to each and every installation and individual usage.

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the disavantage of cassette/ceiling units is that low capacity units are not available. lowest capacity is (to the best of my knowledge) 18,000 btu/h. this makes it mandatory to select an inverter model for rooms smaller than 28-30m² assuming the desired room temperature is not lower than 25ºC. a conventional unit would cycle too often thus dehumidification would be insufficient.

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I have heard that inverters are more expensive to fix...say after a lighting strike,red ant invasion or gecko electrocution.


General service should be about the same, but some replacement parts will be higher, and may be harder to source. That why it is a good idea to get a brand/model that is popular in your area.
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2 hours ago, mogandave said:

Also, they pump the water out so proper draining is less of an issue.

that's in my view a risk issue in case of a pump failure. gypsum ceilings don't like water. aesthetically they are of course unbeatable especially if one has lived many years with central airconditioning and ceiling outlets.

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that's in my view a risk issue in case of a pump failure. gypsum ceilings don't like water. aesthetically they are of course unbeatable especially if one has lived many years with central airconditioning and ceiling outlets.


In the event of a clogged drain, water dried out through the grill, not into the surrounding ceiling.

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2 hours ago, mogandave said:


In the event of a clogged drain, water dried out through the grill, not into the surrounding ceiling.
 

that depends on the indoor humidity level. i had the problem only a years ago in my pool area when the pump failed. fortunately that's the only part of the home which has a different ceiling (cement-wood boards). condensate was not dripping but running (48,000 btu/h, dehumidification at 95% rel. humidity = 12-14 l/h)! the same high level of humidity could occur in a normal room too after airing during rains.

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One overlooked benefit of an inverter air con system is that there is no huge starting surge, This is very important if someone has a solar system.

 

The big difference in your electric bill is that for some reason, air con installation companies like to oversize the systems. It is the too big of a compressor starting and stopping way too often. It doesn't run long enough to dehumidify the area it is cooling so you have a damp cool in addition to a high electric bill. It is difficult to size a unit to exactly your needs because of the constantly changing outside temperature. In the long run you are way better off to deliberately under size your unit. If the compressor runs nearly constantly, it will be as or more efficient than an inverter unit because there is an efficiency loss converting the AC to DC for the inverter compressor.

 

A couple of examples is my bedroom in the condo had a 14,000 BTU unit. I had fungus and mold on the wood inside the bedroom. The new unit is a 10,200 conventional and that problem has disappeared. The bedroom in my home has an old 9,000 BTU conventional unit and that bedroom has never had a dampness problem.

 

Granted that the inverter units will control the humidity much better because they pretty much run constantly at a lower speed. I did buy an inverter for my computer room at home and I can't say that I am overly impressed. It is a 12,200 BTU and if I had it to do over again, I would have bought a 9,000 BTU conventional unit. My computer room air con normally runs only during the day so that pretty much cancels the efficiency gain.

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19 minutes ago, THAIPHUKET said:

So increasing the temperature won't do the
Same as lowering the BTU, correct?

Sent from my HTC One using Tapatalk
 

Since there is no correlation between the temp setting and the BTU size, that would be correct.

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3 hours ago, Gary A said:

In the long run you are way better off to deliberately under size your unit. If the compressor runs nearly constantly, it will be as or more efficient than an inverter unit because there is an efficiency loss converting the AC to DC for the inverter compressor.

:thumbsup:

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15 hours ago, johng said:

I have heard that inverters are more expensive to fix...say after a lighting strike,red ant invasion or gecko electrocution.

not only more expensive but also much more difficult to diagnose a failure and repair. another problem is that a "normal" aircon chang has no idea about the different technical setup of an inverter unit.  

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that depends on the indoor humidity level. i had the problem only a years ago in my pool area when the pump failed. fortunately that's the only part of the home which has a different ceiling (cement-wood boards). condensate was not dripping but running (48,000 btu/h, dehumidification at 95% rel. humidity = 12-14 l/h)! the same high level of humidity could occur in a normal room too after airing during rains.


Not sure what you are saying.
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Since there is no correlation between the temp setting and the BTU size, that would be correct.


But to be clear, when sizing a unit, the difference between the ambient temperature and the desired room temperature is important.

If you want to keep your room at 23 you need a bigger unit that if you are happy with 26.
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25 minutes ago, mogandave said:

 


But to be clear, when sizing a unit, the difference between the ambient temperature and the desired room temperature is important.

If you want to keep your room at 23 you need a bigger unit that if you are happy with 26.

 

Depends on the size of the room and the output temp the unit is capable.  I could put my 9K BTU in a closet and set the temp to 18 and it would happily accommodate.  I could also put it in a large room but it would probably take hours to come to temp.

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27 minutes ago, bankruatsteve said:

Depends on the size of the room and the output temp the unit is capable.  I could put my 9K BTU in a closet and set the temp to 18 and it would happily accommodate.  I could also put it in a large room but it would probably take hours to come to temp.

 

If you are really only happy with a constant cold temperature, then you should have an oversized inverter. As for myself, I am happy to be relatively cool on the hottest days. The beauty of the inverter is that the compressor happily runs at a low speed when it is not that hot outside.

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1 hour ago, mogandave said:

Not sure what you are saying.

translation:

at certain high humidity levels overflowing condense water will not be dried by flowing onto the evaporator fins (as you claimed). when the pump in my Daikin ceiling unit failed water was dripping down at one side of the unit.    

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translation:
at certain high humidity levels overflowing condense water will not be dried by flowing onto the evaporator fins (as you claimed). when the pump in my Daikin ceiling unit failed water was dripping down at one side of the unit.    


I did not claim it would evaporate, I said if the pump quits working, when the drip-pan overflows, the water will drip from the grill.

The evaluators are nice in locations that have no drain, but that is no what I am talking about.
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Depends on the size of the room and the output temp the unit is capable.  I could put my 9K BTU in a closet and set the temp to 18 and it would happily accommodate.  I could also put it in a large room but it would probably take hours to come to temp.


I guess it would depend on what you consider a large room, and what the ambient temperature is.
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14 hours ago, mogandave said:

I did not claim it would evaporate, I said if the pump quits working, when the drip-pan overflows, the water will drip from the grill.

The evaluators are nice in locations that have no drain, but that is no what I am talking about.

 

misunderstanding typo

Quote

mogandave said

water dried out through the grill

 

Edited by Naam
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My old units need to be replaced ( 150 SQM area). Currently set up as : living/dining,  2 old Mitsubishi 18,000 each, covering 75 SQM, 2 bedrooms ( same 18000, one in each). 

Some direct morning sun but not heat of the day. Floor to ceiling on 33% of living, 25% bedrooms.

If I change to inverters, would I need same BTUs? Home pro is saying 24,000 for each unit ( nothwithstanding the fact that they supplied/installed the current ones) ?

I need to make the change before the next hot.

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