Inverter or Non-Inverter Confusion!

P

prakash14

Disciple
Has anyone checked out the Godrej Green Range of ACs. I got a couple of calls from Godrej about their new "6 Star" ACs and I did some research. The MRP is close to 48K-50k based on model but he said final price if I decide. I see it available at around 40K at many online stores.

Based on my research I found that they claim consume less power than many inverter AC's! The EER (COP) works out to 3.7 and many inverter ACs have around 3.6-3.8 range of EER so I was surprised by that figure.

If anyone has an experience it will surely help
 
@6pack Yes if EER is over 3.5 then its a 5Star Rated AC. What they say is its much more than that closer to a 6*. Hence given that inverter AC s have more moving parts while this would have much less moving parts and simpler technology would it make sense to invest in such a AC compared to say an inverter AC?
 
But there is no six star since >3.5 = 5 star. What does number of moving parts got to do with cooling efficiency? The only good thing I can think of is it would be easier to replace parts in years to come. If you can get hold of the spare parts and its not obsolete by some new tech.
 
@6pack - Ok I give up. 5 star. Its just a marketing term 6 Star which would mean much more than 5 Star. But if it is 5 star can some one suggest how efficient it is and how well it cools if anyone has any experience?
By moving parts what I meant is that in inverter technology there are additional sensors / parts involved compared to a regular AC. Further, I am not sure if there are many technicians who have knowledge of repairing the inverter AC if anything goes wrong with it. So was just mentioning it might be easier than inverter or even the reverse may be true that inverter might be easier to repair than a regular AC.
 
Last edited:
@6pack :) Exactly I am really confused if regular ACs have higher EER than Inverter ACs what is the need for inverter ACs? Is it something that we are missing? Say if a regular 5Star AC has an EER of 3.7-3.8 or more, what is the extra benefit of having an inverter AC. Further, if thats the case why spend extra 5k-15k on inverter ACs as some charge a lot of money for the inverter versions.
 
Inverter ACs are not suggested for their EER/star rating. AC companies/BEE rating agency probably know this and hence all inverters have no star rating.

EER ratings are based on steady state conditions. The EER is 3.7 when the Godrej AC is pumping out 5kw of heat and consuming 1.35kw of electricity. You're forgetting that when the compressor starts up, it takes time to reach those steady state conditions where it is actually pumping 5kw, but it consumes 1.35kw throughout. Whats the EER during this process?
A non-inverter compressor keeps turning on and off, so each time it turns on, there's this wastage of energy as it gets up to operating conditions. An inverter avoids this by varying the compressor speed and ensuring its always 'on' and in a steady state condition. There's another side effect of dropping the compressor speed/capacity thats illustrated in singapore's EER labeling : a big compressor running at lower speeds increases the EER significantly.

The other thing I noticed from the inverter threads is that many people are not sizing their ACs to their rooms correctly. So you have a big compressor for a small room that doesn't need it and the AC turns on and off a number of times further dropping efficiency. Or you have an inverter running at a really low load increasing efficiency tremendously like above ^^.
 
@Crazy_Eddy - Yes I agree that there might be some benefits, but in real usage scenario are there any known savings? For example say if we buy a regular 5Star AC for say 35k-40k and say if we buy an inverter AC which costs anywhere from around 46k-55k or even more are the total overall savings more than the extra money we put in? Also is there any major difference in billing.
If we compare between a good inverter AC and a good 5 Star AC I think per hour the max savings in units should not be over .3 units. Now say if a user runs the ac for 10 hours, per day savings are 3 units.
I Read an argument somewhere that if someone runs AC for 100 days total extra units are 300 units. If average electric price is 7 Rs per unit then around 2100 per year. So if a person invests 10k extra it will take him roughly 5 years just to recover the extra investment. Also if 10k were kept in bank he earns 1000 per year.

If anyone understands exact calculation of power consumption and what exact savings are it would definitely help users. I think one needs to calculate between a 5Star good AC and inverter AC and if it is run for 1 hour at same temperature and similar conditions what would be the power consumption.
 
@prakash14 Inverter AC's show their efficiency after a few hours of operation. In the 1st hour, they need to start up the compressor and cool the room. Something which is also done by non-Inverter AC's and inverter one's are no better in this regard.
Only after a few hours of operation, when non-inverter AC's shutdown and after sometime start up again to keep the room cool, will the inverter AC show its capability. Inverter AC will not shutdown. It will go into low power compressor mode to maintain the temperature of the room.
 
@hotshot05 - Yes I would expect that but even if say a person has the AC on for say 5 hours a day how much real power savings can one expect?
If the 0.3 units per hour saving is correct and if as you say the first hour is similar consumption then say for 4 hours it works out to 1.2-1.5 units extra savings.
If you are aware of exact power consumption say first hour then next hour then it can help calculate exact savings.
 
I think the inverter AC's go as low as 800w usage, whereas for a 5 star AC it would be around 1.2Kw. If you ran both ac's for 4 hr's a day you save a unit every day. That's 30 units s month. This is just generalized. In reality normal sc will shut off after it reaches a certain temperature. Then after 15mins or so it will start at full speed again. So in reality probably in 4 hr's you might save around 2-2.5 units with an inverter AC compared to normal AC. People who have used both ac's, correct me if I'm wrong.
 
@6pack - Yes so what I suspect is right. If a user uses the AC for 4-5 hours a day the additional investment in inverter is total waste. Also the savings are all just based on the specifications and as they write "subject to test conditions" Actual may vary :) so if the calculations are right then it makes more sense to invest in a regular 5 Star AC compared to an inverter AC.
 
It depends massively on your heat load and room size, as well as actual usage. Remember that when a regular ac turns off, it turns off. In this state the power consumption is very low, just the IDU idling and fan power. It would be lower than an inverter AC at this point. Of course, when it turns on again it will be pulling a lot more power than an inverter AC, before it stops the next time. Knowing how often the AC turns on and off is the key to extracting maximum savings on TCO.

If you use the ac in short bursts and have a massive heat load, or right size the ac, you can match the savings of an inverter model. Or maybe more. The trick is to oversize. There is a long discussion from a few years ago when inverters had just been introduced.

For those who use an ac for 8 hours a day or so, in burst of 4 hours or more each, an inverter will always work out cheaper to run, and you can get away with a slightly smaller unit than you need, so the initial cooling takes a hit but in the long run it evens out.

There is a balance for each user that is different, though as the laws of marketing go, companies will tend to lavish attention and features on the technology they want to push. This means innovations in rotary ACs will tend to drop over time, and they will be migrated to lower and lower price segments.
 
prakash14 said:
If we compare between a good inverter AC and a good 5 Star AC I think per hour the max savings in units should not be over .3 units. Now say if a user runs the ac for 10 hours, per day savings are 3 units.
Click to expand...
Yes a 30% saving is an accepted average. And yes, whether you can recover your upfront investment in an inverter all depends on how long you run your AC.

I Read an argument somewhere that if someone runs AC for 100 days total extra units are 300 units. If average electric price is 7 Rs per unit then around 2100 per year. So if a person invests 10k extra it will take him roughly 5 years just to recover the extra investment. Also if 10k were kept in bank he earns 1000 per year.
Click to expand...
I'm not sure what the actual prices for 5 star ACs currently are, since even the Godrej seems to be available online for 43k. So assuming a 10k difference is a bit incorrect, I'd say somewhere around 5k. When I did my calcs a year or two back, I found the difference in most cases were recovered in 1~2 yrs because 5 star ACs were too close in price to the Inverter ACs. To keep things as consistent as possible I compared 5 star ACs and Inverter ACs from the same brand. Godrej ACs do not supply inverter ACs so its a bit difficult to make that comparison.

There are a number of side benefits with an inverter compressor continuously running : humidity can still be reduced even under low loads, and temperatures remain a lot more consistent.

Anyway I've seen enough threads to recognise when the OP isn't looking for advice but looking for approval. In your case, I'm guessing you have your heart set on the Godrej, so do let us know how the Godrej works out :)
Just a side note : the Godrej is using Propane as a refrigerant.
 
@Crazy_Eddy -
I'm guessing you have your heart set on the Godrej, so do let us know how the Godrej works out :)
Click to expand...
Not atall. Actually I am not even planning to buy it. Its just that I was told made me wonder if really spending more money on inverter is worth it. I had one Godrej but replaced that with a Sharp Inverter and quite happy with that. Also use OGeneral which again is quite good. But when the Godrej guy told me that regular 5* ACs have better EERs as well as easier to maintain, made me wonder if really it was worth spending 5-10K extra on inverter. (Dont go by online rates - local rates are quite different from what you find online - thats why I have mentioned a range of 5k to even 15k) depending on which brand you choose.
 
prakash14 said:
But when the Godrej guy told me that regular 5* ACs have better EERs as well as easier to maintain
Click to expand...
Its called a good sales pitch. When Godrej releases Inverter ACs, call the guy again and watch his tune change ;)
EERs are only one spec in the whole story. The only thing I can concede is that non-inverters are indeed less complex and have much fewer electronics, so are perhaps easier to repair. But on the flip side, the current inverter ACs look to be a lot better engineered than their non-inverter counterparts.

made me wonder if really it was worth spending 5-10K extra on inverter. (Dont go by online rates - local rates are quite different from what you find online - thats why I have mentioned a range of 5k to even 15k) depending on which brand you choose.
Click to expand...
How much did the Sharp Inverter AC you bought cost you, and what would a similar Sharp 5 star non-inverter cost? Comparing across brands is a bit like comparing apples and oranges.

On a side note maybe you could pitch in with the savings you're seeing with your Sharp Inverter AC. You must be the first Sharp owner on the forum questioning the value in buying an inverter AC, so I feel your electricity bills might be a little more realistic.
 
Damn. Should have bought an Inverter 2 years ago when I bought my Samsung 3 Star. It runs for around 20 hrs a day for nearly 4-5 months. The other AC in the house also runs close to 16 hrs and is due for a change. Will definitely get an Inverter for that room. Both rooms face direct sunlight on walls and roof throughout the day. Will it be a good idea to sell off my 2 year Samsung and get a new Inverter. May get a good deal if I buy 2 ACs together. We are really screwed in the summer months due to the electricity bills. Easily cross 6k a month during those days.
 
@Crazy_Eddy - I think I paid close to 46 or 47k for the sharp with installation. The non inverter 5 Star was quoted at around 37-38 range. Hence the difference in price was close 8-9k. Though I have not seen any major change in my bills overall I think the inverter AC is saving close to say around 20% in power. This is compared to the old 3 Star AC that we had. A 3 star AC for that matter is around 25-30k range! So compared to that the price difference is roughly 20K for a saving of around 20-30% power. If we go by current statistics of say even 3 units saved per day and say if a person uses ac for 100 days a year then 300 units saved. So it would take ages to recover. I think the savings are only for people running their AC 24 / 7 for say 200-300 days a year then yes recovery of investment is quite fast. But if its around 4-5 hours a day and say 100 days a year, I am not really sure of investing in an inverter AC.
 
prakash14 said:
@Crazy_Eddy - I think I paid close to 46 or 47k for the sharp with installation. The non inverter 5 Star was quoted at around 37-38 range. Hence the difference in price was close 8-9k. Though I have not seen any major change in my bills overall I think the inverter AC is saving close to say around 20% in power. This is compared to the old 3 Star AC that we had. A 3 star AC for that matter is around 25-30k range! So compared to that the price difference is roughly 20K for a saving of around 20-30% power. If we go by current statistics of say even 3 units saved per day and say if a person uses ac for 100 days a year then 300 units saved. So it would take ages to recover. I think the savings are only for people running their AC 24 / 7 for say 200-300 days a year then yes recovery of investment is quite fast. But if its around 4-5 hours a day and say 100 days a year, I am not really sure of investing in an inverter AC.
Click to expand...

Let me put a different perspective to the inverter vs non-inverter war.
An inverter AC consumes less current after it has cooled the room. So you are placing less load on the electricity grid. You may think that it is better for the electricity supply company if your AC consumes more power but it is not. There is an electricity shortfall all over India. If your AC consumes less power, someone else in the grid may be able to enjoy the fan/light/TV in his room instead of a blackout.
I don't know what the power situation is in your area but in west Bengal, during the peak hours there are power cuts sometimes. The frequency has greatly reduced over the years but it is there sometimes. But WB is an electricity surplus state because of low level of industries here. In industrialized areas, the problem will be a lot more.
 
Back
Top