[alpha1]

Originally Posted by khoj

Gentlemen, now that I have your attention please take a few minutes to help out a non member reader of team-bhp. Manik is from Ludhiana and he messaged me on another forum seeking guidance from our in house experts here on this thread. I am posting his message verbatim for your perusal and recommendations.

First thing first:
A) 1 ton load = 12000 BTU/h
BTU = unit of heat
BTU/h = unit of power

B) Average human produces about 300 BTU/h
This is almost the same amount of heat given off by an 80 W bulb!

C) Solar irradiation produces roughly 300 BTU/h per square foot of normal surface. But since the walls act like insulators, you get much less heat inside the room! Also because the sun's rays are not perpendicular to the wall exposed to sun this number reduces drastically.
http://nptel.iitm.ac.in/courses/Webc...cture%2032.pdf
Lets take about 150 Btu/h per square foot of wall exposed to direct sun.

As long as the total heat in (because of human beings and sun) is less than 12000 BTU, your AC will produce cooling.

I have found out the optimum tonnage for the room should be about 1.1 ton. However, the 1ton inverter can overwork itself upto 1.2tons initially to cool faster, hence overcoming the problem.

There is no "overworking" as such. A 1 ton AC = 1 ton AC only = can remove 12000 BTU of heat every hour.

What happens is that when you use a lower capacity AC, the time taken to reach your desired temperature will be slow. Hence, 1 ton AC will work fine, but take longer to reach your desired temperature compared to a 1.5 Ton AC.


The Inverter (VFD) AC is nothing great (contrary to what advertisement and general marketing wants you to believe). All it does it regulate the compressor duty in order to reach the desired temperature. Which means it won't run continuously at 12000 BTU/h, but regulate it down when not required.

Pshh! Doesn't the normal on-off AC does the same thing? When your AC has produced desired temperature, it shuts off the compressor.

So what advantage does the VFD offer? It offers slightly better electrical efficiency (that means less power consumed for same cooling). But I will be darned if you can see a significant difference in your elec bills!

Another advantage which this offers is the set temperature (say your friend likes 23 deg C, will be achieved more finely. Since the compressor is running all the time.

Normal AC will shut off, let the temperature raise till 23.5 or 24, and then kick in. Drop the temp to 22 or 22.5. And repeat the cycle.

Normal power consumption of a 5star 1.5ton AC is about 1600W while for the one ton is just 950 watts. Even with 50:50 ratio of on-off cycle, the average power consumption for 1.5 ton will average out to be near 800w. The 1 ton one might consume additional power at first but when temperature will stabilize, it'll end up using almost same or maybe even less power. Hence there is no justification to spending 12k extra on 1.5ton AC.

The on-off cycle for a 1 ton AC will be 60:40, but for 1.5 ton AC will be 40:60
But you are right, it won't make much difference to the elec bills.

[sai_ace]

Hello all,

In the process of finalizing an AC for a 16x11 room with one window facing west. Have been told 1.5 Ton ac would do the job. Plus this being coimbatore i dont see the AC doing duty beyond August september on a regular basis.

I am only looking at Daikin and Panasonic . Not looking at any inverter model.

The Models I have chosen are

Daikin - http://www.daikinindia.com/pdf/split...5m-50-60nr.pdf

Panasonic - http://www.panasonic.co.in/wps/porta...hire/cskc18pky


If you see the prices are similar. I would like your suggestions and probably why an one of these and why not.

The Daikin is a 3 star unit while the Panasonic is a 5 star unit.

And also a suggestion for a good voltage stabilizer as CBE sees frequesnt power cuts.

cheers!
sai

[Inquisitive]

Originally Posted by alpha1

So what advantage does the VFD offer? It offers slightly better electrical efficiency (that means less power consumed for same cooling). But I will be darned if you can see a significant difference in your elec bills!

In Kolkata, the 1.5T inverter model that I have generally runs 8 hrs in the night (9PM-5AM) for a west facing 176 sq, ft. room which is reasonably warm when the AC is not turned on. I generally set the temp at 24C with ceiling fan on. The increase in my electricity bill per month has never been in excess of Rs. 700. Right now i cannot give you the exact number of units consumed per month but i suppose this is reasonable. also cannot comment on whether a non-inverter model would have done the same as this is the first and only ac in the household.

[sgiitk]

@sai_ace; Are they R410a or R22?

[Prowler]

Originally Posted by naveen.raju

Guys, I have a question. Have been using Voltas 2.5 ton AC in my bedroom for many years. Few days back, it's failing to cool. The AC mechanic cleaned the unit, replaced the capacitor and still no luck. He said that compressor needs to be changed and said it would cost around 10k. I doubt whether the compressor is at fault since the compressor fan is working. If I need to change the compressor, will a 1 ton compressor work fine with this 2.5 ton split? The room is pretty big with two laptops running throughout the night.

Expecting a quick response. Need to make a decision tomo.

What decision did you take ?
As bluevolt said compressor and the fan can fail independent of each other. If the compressor had failed, the fan may continue to work. That said, it is unlikely that compressors fail by open circuit. Usually they short out resulting in your MCB tripping. So check with another AC technician if the compressor had really failed. It could be OLP (Over Load Protector) which fails at more frequent rates than the heavy duty compressor.

You can fix a one ton compressor in a 2.5 ton unit. But the compressor will be forced to work all the time resulting in shorter life. For short term usage, it is still done.

[naveen.raju]

Originally Posted by Prowler

You can fix a one ton compressor in a 2.5 ton unit. But the compressor will be forced to work all the time resulting in shorter life. For short term usage, it is still done.

I'm planning to go for second hand 2.5ton compressor or go for a new 1ton. Have to check the prices and condition. As per the AC technician, he confirmed that the compressor has failed. He quoted around 10-12k for a 2.5ton compressor and 5-6k for 1ton. Shall check the market and a local second dealer later this week. Will update my decision here.

[Prowler]

Originally Posted by naveen.raju

I'm planning to go for second hand 2.5ton compressor or go for a new 1ton. Have to check the prices and condition. As per the AC technician, he confirmed that the compressor has failed. He quoted around 10-12k for a 2.5ton compressor and 5-6k for 1ton. Shall check the market and a local second dealer later this week. Will update my decision here.

I would suggest that you go for a new compressor. If your luck runs out, you may get a about-to-die compressor. I had a WestingHouse 2 ton ac which needed a compressor about 10 years ago. They replaced it with a secondhand unit which promptly conked off after only 3 months. I had to buy a new Kirloskar compressor.

[naveen.raju]

Originally Posted by Prowler

I would suggest that you go for a new compressor. If your luck runs out, you may get a about-to-die compressor. I had a WestingHouse 2 ton ac which needed a compressor about 10 years ago. They replaced it with a secondhand unit which promptly conked off after only 3 months. I had to buy a new Kirloskar compressor.

Thanks Prowler. Will check this as well. Also, I assume any brand would be fine. Or do we have to stick with the same brand? My split is Voltas so should I stick with the same brand or go for any brand? I actually have a spare Lloyd split AC is another room but isnt much effective. I also had in my mind to take this unit or atleast the compressor. But the problem is that my room is huge with two systems running. I have a doubt whether this 1ton Lloyd will do the trick.

[Prowler]

Originally Posted by naveen.raju

Thanks Prowler. Will check this as well. Also, I assume any brand would be fine. Or do we have to stick with the same brand? My split is Voltas so should I stick with the same brand or go for any brand? I actually have a spare Lloyd split AC is another room but isnt much effective. I also had in my mind to take this unit or atleast the compressor.

Any brand with a warranty is fine.

But the problem is that my room is huge with two systems running. I have a doubt whether this 1ton Lloyd will do the trick.

It depends on the heat load. If you are comfortable with the idea of Ambient temperature minus 5 degree C as a ballpark figure, then a one ton split will just about serve the need. If you are the Rohtang Pass type, you need to use the 2.5 ton unit with a new compressor - even with a one ton compressor. The cooling will not be equivalent to a true 2.5 ton, but will be better than a one ton. I was the Maintenance Engineer for a 3 star hotel long time ago. And this sort of thing was common practice in those days.

[naveen.raju]

Originally Posted by Prowler

Any brand with a warranty is fine.



It depends on the heat load. If you are comfortable with the idea of Ambient temperature minus 5 degree C as a ballpark figure, then a one ton split will just about serve the need. If you are the Rohtang Pass type, you need to use the 2.5 ton unit with a new compressor - even with a one ton compressor. .

Thanks a lot for your valuable inputs. Will check the 1ton split and see if it's sufficient else will get a new compressor.

[sai_ace]

Originally Posted by sgiitk

@sai_ace; Are they R410a or R22?

sir, the daikin is R22. The Panasonic one I am unable to find from anywhere.

cheers!
sai

[naveen.raju]

Originally Posted by Prowler

Any brand with a warranty is fine.
.

Got it checked by another local AC mechanic. He confirmed that the compressor has failed. He gave me two options.
1) 2nd hand compressor for 5k with 6 months warranty.
2) A new compressor for 13.5k with 1 year warranty (includes gas filling and labor)

Called up Voltas customer care and explained the problem. They will charge 400/- for the initial checkup and for the new compressor 10k with 5 year warranty. Total bill will be 10400/-. Much better deal when compared to the local mechanic. Got the request ID and said they would initiate the process in 24 hours. Hopefully the representative will check the unit tomo.

[Prowler]

Originally Posted by naveen.raju

Got it checked by another local AC mechanic. He confirmed that the compressor has failed. He gave me two options.
1) 2nd hand compressor for 5k with 6 months warranty.
2) A new compressor for 13.5k with 1 year warranty (includes gas filling and labor)

Called up Voltas customer care and explained the problem. They will charge 400/- for the initial checkup and for the new compressor 10k with 5 year warranty. Total bill will be 10400/-. Much better deal when compared to the local mechanic. Got the request ID and said they would initiate the process in 24 hours. Hopefully the representative will check the unit tomo.

Good call Naveen. You get a brand new compressor with 5 year warranty from the manufacturer and the price is right too. For all practical purposes it is like getting a new unit. Just make sure that they give you the written warranty for 5 years.

[naveen.raju]

Originally Posted by Prowler

Good call Naveen. You get a brand new compressor with 5 year warranty from the manufacturer and the price is right too. For all practical purposes it is like getting a new unit. Just make sure that they give you the written warranty for 5 years.

Definitely. Will look into this and keep you posted. Thanks a lot for your guidance.

[Aceman82]

My bad luck with Tata products never seems to end . My Voltas Vetris Elite's Jan 2012 make (or it elegant ?) cooling coil has failed with it having two microscopic leaks at two places.

It was weird since my other room has a Voltas AC (Vertis Gold pre 2011..i guess 2010) and it is running like it was from Day1 with no issues. On closer inspection the mechanic said that the older Voltas AC comes with Copper Coil which in general does not fail and even if it fails it can be welded but after 2011 all Voltas AC as a cost cutting measure comes with the Aluminum Coil which has a serious failure rate and being aluminium it cannot be welded also (in the past week with this AC mechanic 75 Coils of Voltas Elite/Equivalent has failed). I guess Chennai conditions does not help matters also.

Then again my Videocon and Kelvinator AC's (3 Star rated) seems to cool properly and much faster, never had issues and was pretty cheap to buy. Six month ago, i would have wagered on those to go kaput and not my Voltas which costed a lot,lot more and came with 5 Star rating.

Anyways to make a long story short the whole fiasco costed some Rs:7000 for a new coil and gas refilling. The last tata product in my home is Tata Sky HD, i hope that does not fail since it would make a perfect trio