The home / office air-conditioner thread

Thad E Ginathom · 27th March 2010, 18:28

That's a very nice explanation, and, for when I next buy, you have sold me the idea

anupmathur · 28th March 2010, 07:55

Khoj, thanks, that's nicely explained, but....now consider a situation where there are no traffic signals!

Looking around in Delhi, a city that suffers truly hostile summers, I find that in most 'commercial' places the ACs are continuously on, struggling to get to the set temperature!
This is the scenario in a lot of shops/stores and many offices.
These people will see absolutely no difference in their power bills.

In a home environment, or in well designed office premises where AC plant sizing has been generous and insulation has been applied there will, no doubt, be savings.

In short, savings will only be realized where the compressors are cycling (on-off) and the more they cycle the greater would be the savings.

An under-sized AC where the compressor is always on most of the time that the AC is in use will offer very disappointing savings, if any at all!

I wish manufacturers would explain this point clearly to customers before they shell out the money for these very expensive ACs!

Gansan · 28th March 2010, 07:58

@anupmathur
I think the concept will come in to play only at night during our summers. During the day time the compressor will be running for most of the time anyway!

khoj · 28th March 2010, 14:08

Guys,

Before you start jumping to conclusions go through the link below. Inverters have been in use for many years now and proven their credibility in areas such as Australia which sees ambient temperatures as high as North India if not higher and in the Gulf where for months together the ambient is beyond the mid 40s.

Explore the link VRV system | Product | Daikin Industries, Ltd.

Commercial establishments here face the same challenges as those in the Gulf. However there are many other components and factors in a large building which will effect the overall cooling/heating efficiency and those would be fodder for another thread all together.

Sheel · 28th March 2010, 14:19

with pretty limited options would you suggest Videocon Split 1.5T?
the only good brand available is Blue-Star and it has been advised to not buy Carrier,
Hitachi and General isn't available, wouldn't want to go for Samsung/LG though Godrej, Voltas are present
advise please

Guite · 28th March 2010, 14:23

Recently there was a discussion on the convinience of shifting a split unit vs window unit. Well, I just finished shifting a split unit and can give the cost perspective. Uninstallation cost Rs1200 last year. Re-installation cost Rs.5000 (including Rs.2500 for gas refill) and it took more than 4 hours. All the concrete and brick dust are pretty messy as well.

Sorry if this have been discussed before: does the gas have to be re-filled at every re-installation?

anupmathur · 28th March 2010, 18:05

Quote:

Originally Posted by Guite

....
Sorry if this have been discussed before: does the gas have to be re-filled at every re-installation?

Yes it has been discussed before!
There are valves on the outdoor unit pipelines. These should be shut in the correct sequence (liquid line first) with the AC running.
Most of the gas will now be trapped in the condenser.

After re-installation at new location the unit will at best need only a small top-up charge of refrigerant, if any is required at all.

kjmads · 28th March 2010, 19:26

Quote:

Originally Posted by EssYouWe

Hi,

I bought a LG 1.5 Tonne ......... for Rs.16000/-.

Any comments on whether I was ripped off or I got a good deal...?

Having bought it, just go ahead and enjoy the summer. It seems to be a good price for a 1.5TR SAC although I am not a fan of LG products.

Thad E Ginathom · 28th March 2010, 21:00

If an AC compressor is running all the time and struggling to reach even the set temperature, then it is indeed under-spec, and something of an expensive mistake. False economy at the time of purchase.

I was once told by an engineer that over-spec is not a good idea either. Something about cooling the room too fast, again causing cutting in and out too often.

Guite · 28th March 2010, 21:44

Quote:

Originally Posted by anupmathur

Yes it has been discussed before!
There are valves on the outdoor unit pipelines. These should be shut in the correct sequence (liquid line first) with the AC running.
Most of the gas will now be trapped in the condenser.

After re-installation at new location the unit will at best need only a small top-up charge of refrigerant, if any is required at all.

Thanks Anup for posting it again for me. Now I have to go back to one of your post where you identified the pipes by size and find out for myself which pipe is gas and which .....

anupmathur · 28th March 2010, 21:48

Quote:

Originally Posted by Guite

Thanks Anup for posting it again for me. Now I have to go back to one of your post where you identified the pipes by size and find out for myself which pipe is gas and which .....

Hehe, the gas pipe is the larger diameter, liquid pipe smaller dia.

anupmathur · 28th March 2010, 21:51

Quote:

Originally Posted by Thad E Ginathom

If an AC compressor is running all the time and struggling to reach even the set temperature, then it is indeed under-spec, and something of an expensive mistake. False economy at the time of purchase.
....

Thad, think about it - an undersized AC will behave exactly the same as the inverter type in terms of power consumption!!
It might leave you a tad disappointed by not quite cooling to the required degree! But you'll be all smiles seeing the electricity bill at the end of the day!

kjmads · 28th March 2010, 22:47

Quote:

Originally Posted by anupmathur

Thad, think about it - an undersized AC will behave exactly the same as the inverter type in terms of power consumption!!
It might leave you a tad disappointed by not quite cooling to the required degree! But you'll be all smiles seeing the electricity bill at the end of the day!

It depends on how much undersized the AC is. To match the power consumption of an inverter type, the normal rotary type has to be very much under sized. In which case, the cooling effect will be disappointing. And it is not a great idea to keep the normal RAC running continuously, as it is not built for that kind of an operation.
To match the opex of inverter RACs with normal rotary RACs is not possible. It is an application based and capex decision whether one has to go for Inverters.
The cost of Inv. type AC is about 50% more than a equivalent capacity premium normal rotary split.

Thad E Ginathom · 28th March 2010, 23:30

I suspect that the greatest running-cost economy is that of a correctly-sized unit.

(And I am used to being a Thad disappointed

)

anupmathur · 29th March 2010, 07:30

Quote:

Originally Posted by kjmads

It is an application based and capex decision whether one has to go for Inverters.
....

I agree!

Quote:

Originally Posted by kjmads

..... And it is not a great idea to keep the normal RAC running continuously, as it is not built for that kind of an operation.

I don't agree.
Is there a duty cycle specified anywhere?

Quote:

Originally Posted by Thad E Ginathom

....
(And I am used to being a Thad disappointed

)

Honest, I did not have pun in mind when I wrote that!

27th March 2010, 18:28	#841
Thad E Ginathom Distinguished - BHPian Join Date: Jun 2007 Location: Chennai Posts: 11,004 Thanked: 26,435 Times	That's a very nice explanation, and, for when I next buy, you have sold me the idea
	() Thanks

28th March 2010, 07:55	#842
anupmathur Senior - BHPian Join Date: Sep 2007 Location: New Delhi Posts: 3,095 Thanked: 307 Times	Khoj, thanks, that's nicely explained, but....now consider a situation where there are no traffic signals! Looking around in Delhi, a city that suffers truly hostile summers, I find that in most 'commercial' places the ACs are continuously on, struggling to get to the set temperature! This is the scenario in a lot of shops/stores and many offices. These people will see absolutely no difference in their power bills. In a home environment, or in well designed office premises where AC plant sizing has been generous and insulation has been applied there will, no doubt, be savings. In short, savings will only be realized where the compressors are cycling (on-off) and the more they cycle the greater would be the savings. An under-sized AC where the compressor is always on most of the time that the AC is in use will offer very disappointing savings, if any at all! I wish manufacturers would explain this point clearly to customers before they shell out the money for these very expensive ACs!
	() Thanks

28th March 2010, 07:58	#843
Gansan Senior - BHPian Join Date: May 2009 Location: Chennai Posts: 4,535 Thanked: 5,552 Times	@anupmathur I think the concept will come in to play only at night during our summers. During the day time the compressor will be running for most of the time anyway!
	() Thanks

28th March 2010, 14:08	#844
khoj Senior - BHPian Join Date: Sep 2008 Location: Dilli Posts: 2,718 Thanked: 1,287 Times View My Garage	Inverters continued VRV Guys, Before you start jumping to conclusions go through the link below. Inverters have been in use for many years now and proven their credibility in areas such as Australia which sees ambient temperatures as high as North India if not higher and in the Gulf where for months together the ambient is beyond the mid 40s. Explore the link VRV system \| Product \| Daikin Industries, Ltd. Commercial establishments here face the same challenges as those in the Gulf. However there are many other components and factors in a large building which will effect the overall cooling/heating efficiency and those would be fodder for another thread all together.
	() Thanks

28th March 2010, 14:19	#845
Sheel Team-BHP Support Join Date: Jul 2006 Location: Purnea (Bihar) Posts: 9,584 Thanked: 14,402 Times View My Garage	with pretty limited options would you suggest Videocon Split 1.5T? the only good brand available is Blue-Star and it has been advised to not buy Carrier, Hitachi and General isn't available, wouldn't want to go for Samsung/LG though Godrej, Voltas are present advise please
	() Thanks

28th March 2010, 14:23	#846
Guite BHPian Join Date: Jul 2008 Location: Noida, NCR Posts: 733 Thanked: 630 Times	Recently there was a discussion on the convinience of shifting a split unit vs window unit. Well, I just finished shifting a split unit and can give the cost perspective. Uninstallation cost Rs1200 last year. Re-installation cost Rs.5000 (including Rs.2500 for gas refill) and it took more than 4 hours. All the concrete and brick dust are pretty messy as well. Sorry if this have been discussed before: does the gas have to be re-filled at every re-installation?
	() Thanks

28th March 2010, 21:00	#849
Thad E Ginathom Distinguished - BHPian Join Date: Jun 2007 Location: Chennai Posts: 11,004 Thanked: 26,435 Times	If an AC compressor is running all the time and struggling to reach even the set temperature, then it is indeed under-spec, and something of an expensive mistake. False economy at the time of purchase. I was once told by an engineer that over-spec is not a good idea either. Something about cooling the room too fast, again causing cutting in and out too often.
	() Thanks

28th March 2010, 23:30	#854
Thad E Ginathom Distinguished - BHPian Join Date: Jun 2007 Location: Chennai Posts: 11,004 Thanked: 26,435 Times	I suspect that the greatest running-cost economy is that of a correctly-sized unit. (And I am used to being a Thad disappointed )
	() Thanks