[AWD]

Originally Posted by khoj

Well inverter would be the more economical Daikin inverter range be careful with what model you go for. There is one where the minimum rating is 230W and then yet another where the minimum rating is 750W. IDU which is less than 30" and will replace my decade+ old Hitachi Atom also with an IDU of < 30

Thanks, I had also narrowed down to an Inverter AC untill a local dealer persuaded me against one. The reason he mentioned was that the DC Inverter motor costs around 18-20k. Now I dont know how right/wrong he was, would like to confirm this here from the experts. He was also pushing me towards a 5* instead of an Inverter, maybe it was a stock issue, I dont know.

In Door Unit(IDU) < 30", you need a small IDU ? I dont have any space constraints as such.

Also enlighten me a bit more on 230/750W thing. I have a mitsubishi Split(5*) installed at flat but Im not happy with its cooling. It does have some great air throw but outright cooling aint there, eg. an LG installed in other room cools much faster & better. Have shown the machine many times to service personnel but they say this is normal for the AC.

Another dealer was going gaga over LLoyd & Onida, I dont have any experience with both the brands. These are leser brands than Diakin, Mitsu for sure.

[sweetvar26]

Originally Posted by AWD

Thanks, I had also narrowed down to an Inverter AC untill a local dealer persuaded me against one. The reason he mentioned was that the DC Inverter motor costs around 18-20k. Now I dont know how right/wrong he was, would like to confirm this here from the experts. He was also pushing me towards a 5* instead of an Inverter, maybe it was a stock issue, I dont know.

In Door Unit(IDU) < 30", you need a small IDU ? I dont have any space constraints as such.

Also enlighten me a bit more on 230/750W thing. I have a mitsubishi Split(5*) installed at flat but Im not happy with its cooling. It does have some great air throw but outright cooling aint there, eg. an LG installed in other room cools much faster & better. Have shown the machine many times to service personnel but they say this is normal for the AC.

Another dealer was going gaga over LLoyd & Onida, I dont have any experience with both the brands. These are leser brands than Diakin, Mitsu for sure.

I might not be entire right about this but of what I've read, Inverter AC's are effective as long as the outside temperature is less than 46 degrees. If it's higher than that, the traditional AC's are supposedly better.

I'm in the market for an Inverter AC as well, been doing some research on it. Go with the higher EER, usually the cost goes up too but so are the power savings.

[alpha1]

So, yesterday I uncovered one of the great scam making rounds in our country:
SIR, you need X.X tonnage A/C for your house/shop/building!

To confound the matters more, we have the "inverter" AC (idiots should have simply called it variable frequency drive - VFD - a term actually used in the industry).

To cut the matters, short: all of you (one this thread) could've done with a smaller AC running more efficiently, consuming less power, and handling the humidity much better, but have been conned by the entire industry of folks passing themselves as HVAC engineers. Would you believe if I told you that industrially (where money matters a lot) the rule of thumb globally used by DIY builders is: 1 ton per 600 sqft of floor? (And even then it may be over rated, hence specific thermal load calculations are required).


Edit: And now I looks back, my parents had purchased 1.5T a/c a few years back. The a/c compressor works not even 20% of the times! What a waste!!!

[fine69]

Originally Posted by alpha1

Would you believe if I told you that industrially (where money matters a lot) the rule of thumb globally used by DIY builders is: 1 ton per 600 sqft of floor? (And even then it may be over rated, hence specific thermal load calculations are required).

But then what about the other factors such as Ambient temperature?

Are you really saying that in a place like Delhi with a weather that we've encountered in the last week, a 1 ton AC would be able to maintain a 20-22 degree temperature in a 25' x 24' hall?

[sgiitk]

Originally Posted by fine69

Are you really saying that in a place like Delhi with a weather that we've encountered in the last week, a 1 ton AC would be able to maintain a 20-22 degree temperature in a 25' x 24' hall?

I do not think even a 2TR will be adequate. A couple of days ago while driving from Kanpur to the NCR I even felt a power drop in my Civic due to the heat, after midday. Normally, the IVTEC cm does not come on, but this time it was cutting in frequently.

[alpha1]

Originally Posted by fine69

But then what about the other factors such as Ambient temperature?

Are you really saying that in a place like Delhi with a weather that we've encountered in the last week, a 1 ton AC would be able to maintain a 20-22 degree temperature in a 25' x 24' hall?

The 1.5T example I was giving was for Delhi only! Peak summer of 43-45 deg C - room size 12'x12' + 10'+12' (roughly) The rooms are little staggered.

The outdoor wall is on the west side. So it does experience direct sun, and there is a long window also on this wall.

I have seen that when I set temperature of about 25 deg C (I somehow feel extremely uncomfortable with 16-21 range that most people prefer), the compressor works straight for 1-1.5 hour or so, and once the desired temperature is reached it follows the cutoff cycle mentioned.

Come to think of it, what exactly is tonnage of an AC?
I am not asking for a number, I am asking what does the tonnage describe (ability to ____)

Originally Posted by sgiitk

I do not think even a 2TR will be adequate. A couple of days ago while driving from Kanpur to the NCR I even felt a power drop in my Civic due to the heat, after midday. Normally, the IVTEC cm does not come on, but this time it was cutting in frequently.

Cars are greenhouses. Homes are usually not.
100T AC can chill the desired parcel of air to frost in a matter of seconds.
1T AC may take 1000 seconds to achieve the same.
Impatience determines the tonnage (of course the heat influx also does).

[fine69]

Originally Posted by alpha1

I have seen that when I set temperature of about 25 deg C (I somehow feel extremely uncomfortable with 16-21 range that most people prefer), the compressor works straight for 1-1.5 hour or so, and once the desired temperature is reached it follows the cutoff cycle mentioned.

My previous rented house was open from all sides. Even I don't prefer anything less than 24 degrees and usually sleep at a temp. of 26-27.

However, if an AC takes 1.5 hours to reach the temperature of 25 degrees then that's not really what most consumers want. Not to mention, what about those times when I want a 22-23 degree temp?

I mean one would want the room temperature to start going down within the first 3-5 mins and at max 10-15 mins for it to reach the desired level. Otherwise the fun of having an AC just isn't there, at least for me.

Originally Posted by alpha1

Come to think of it, what exactly is tonnage of an AC?
I am not asking for a number, I am asking what does the tonnage describe (ability to ____)

Ability to draw that kind of electricity and get the meter running really fast.

In all honesty, 1.5 ton for me is simply an equipment that draws ~1500 watts of power and cools my room in a reasonable time. It should be the ability of an equipment to draw certain power and cool certain volume of air in a certain time.

If the ice melts uniformly over the 24 hours, it absorbs heat at the rate of 286,000 / 24 hrs = 11,917 BTU/hr. Rounding that number up makes it a nice, round 12,000 BTU/hr. In air conditioning jargon, then, a ton of AC capacity is equal to 12,000 BTU/hr. There it is.

Source - Google

[sgiitk]

Let me add, in our old home at IITK our 1TR AC barely managed our bedroom, all of 11x14 in the afternoon. So a 20x24 will need 3 Tonnes plus. Also, cars are glasshouses, but then they have always been. This is the first time I have seen the engine output drop in the summer!

[alpha1]

Originally Posted by fine69

I mean one would want the room temperature to start going down within the first 3-5 mins and at max 10-15 mins for it to reach the desired level. Otherwise the fun of having an AC just isn't there, at least for me.

I agree, and that's what I have said in my previous post.
But lets see the thing about tonnage = ability to remove heat.

So, in a house:
1. the AC's ability to remove heat (let's measure in BTU/h)should be greater than the house's ability to add heat (via electrical equipment, living beings and insolation), otherwise the temperature will never start coming down.
2. the speed of heat removal (and thus the temperature drop) should be within tolerable limits

This is where we encounter the human tendency:
Impatience = lack of ability to wait for an event/outcome

Now the funny thing is this, impatience (like most other human sensory perceptions) is logarithmic. If certain AC takes 1 hour to cool to desired, and another takes 1 hour 10 minutes, you would hardly care. But if the third one takes 30 minutes, you will notice it (but not really impressed).

To reach from 1 hour cooling effort to 30 minutes, you will require double the tonnage. To reach from 1 hour cooling effort to 10 minutes (impressive!) will require 6 times the tonnage.

It is the matter of where (time limit wise) you start getting impressed.


Since we all deal with the realities and limitations of life we choose to use curtains, awnings etc-to never allow the inside temperature to ever reach the 45 deg C that outside world is experiencing.

Also since we know that we are highly impatient, we start our AC well in advance (say by 11 am instead of waiting till 2 pm). In this case, the question of waiting for the desired temperature will never arise!



###
By the way, in Delhi's peak heat air's relative humidity is well below 20%. At this, one starts feeling comfortable even if the dry bulb temperature drops to 30-32 deg C. So it is not that I am sitting uncomfortable for the first 1.5 hours!! In fact within the 15-30 mins I can start feeling the "cold".

[Lord Lucan]

Originally Posted by sweetvar26

I might not be entire right about this but of what I've read, Inverter AC's are effective as long as the outside temperature is less than 46 degrees. If it's higher than that, the traditional AC's are supposedly better.

I'm in the market for an Inverter AC as well, been doing some research on it. Go with the higher EER, usually the cost goes up too but so are the power savings.

I am in the market for ~1 ton inverter AC as well. Sharp operates upto 48 degrees, general upto 46 degrees & latest whirlpool upto 52 degrees.

[fine69]

I purchased a Daikin 1.5 ton split last year from snapdeal. When I called them to request for a wet service I was told that if I've bought it off any of the ecommerce websites the warranty is void and there are no free services. So now I'll be paying 1200 plus service tax, thought I'll share with you all.

[diyguy]

Originally Posted by fine69

I purchased a Daikin 1.5 ton split last year from snapdeal.

That's a crazy situation. Did you speak to Snapdeal support? You should have got a dealer invoice along with the product. Call that person. Also I don't think free service is that big a loss but the warranty is an issue. The free services are a joke and they just clean the filter and a little more. I turned away the samsung guy when he refused to clean the outdoor unit for me under free service. Decided not to waste time with them.
With the 1200 are they restoring the warranty as well?

[lapis_lazuli]

Originally Posted by alpha1

we have the "inverter" AC (idiots should have simply called it variable frequency drive - VFD - a term actually used in the industry).

The more modern inverter AC does not have a VFD imho. It is called an inverter AC because, it has a BLDC motor compressor inside, and it needs a 3 phase trapezoidal current drive to run it provided by a "inverter" circuit essentially a chopped DC to AC converter. (Though similar topology like a 3 phase VFD drive. The driving scheme is NOT variable frequency.) A BLDC provides smoother control, high electrical efficiency and more silent operation in contrast to reciprocating compressors.

BLDC: BrushLessDC
VFD: Variable frequency drive

Please see, as an example,

http://sg.renesas.com/media/india/so...onditioner.pdf

[alpha1]

Originally Posted by lapis_lazuli

The more modern inverter AC does not have a VFD imho. It is called an inverter AC because, it has a BLDC motor compressor inside, and it needs a 3 phase trapezoidal current drive to run it provided by a "inverter" circuit essentially a chopped DC to AC converter. (Though similar topology like a 3 phase VFD drive. The driving scheme is NOT variable frequency.) A BLDC provides smoother control, high electrical efficiency and more silent operation in contrast to reciprocating compressors.

BLDC: BrushLessDC
VFD: Variable frequency drive

Please see, as an example,

http://sg.renesas.com/media/india/so...onditioner.pdf

You may be right, and perhaps I have to eat the humble pie about my comment.

But, VFD also is basically an inverter circuit.
Where we differ is that I am saying that DC is converted (inverted) back to AC with varying frequency to drive 3ph AC motor.
You are saying that DC is converted to pulse width modulated signal to drive a brushless DC motor (which is essentially is a synchronous AC motor).

Does trapezoidal wave control results in better performance compared to sinusoidal? (I am not an electrical engineer, so pardon me if this sounds very basic).

In my view an squirrel cage motor should work out to be cheaper than a BLDC (essentially a synchronous). The power electronic circuitry for waveform should be similar priced for sinusoidal vs trapezoidal.

[alpha1]

Originally Posted by fine69

I purchased a Daikin 1.5 ton split last year from snapdeal. When I called them to request for a wet service I was told that if I've bought it off any of the ecommerce websites the warranty is void and there are no free services. So now I'll be paying 1200 plus service tax, thought I'll share with you all.

How can Diakin claim/prove that you bought the product online?
The seller invoice/receipt/bill will remain the same, whether you bought the product from brick and mortar store or off e-commerce website.

Flipkart/Amazon/Snapdeal/eBay doesn't sell anything on their own, they are marketplace.

So the entire argument of Daikin (and others like Nikon) simple must be flushed down the toilet whenever they make such excuses.