Inverter AC for 120~145 Sq Ft Bedroom

[swapnil0545]

I would rather think that we will be buying 410a gas A.C with copper material and having inverter is better. This is future proof, technology and nature friendly.

But if you are just going to use your AC in nights and in summer then its better to buy 3 star A.C(3.10EER+) the savings will be more comparitively.

 

[prakash14]

Thank you for the straight answer.

So it seems for two identically priced Inverter & non-Inverter (5-Star) you will always opt for 5-star ACs irrespective of any usage pattern. I wonder how come between two identically priced Inverter and non-Inverter (5-Star) ACs one is going to have more long term maintenance cost over the other. After all both costs the same so their components will be of more or less of equal price. Isn't it?

Yes, if there is no requirement for inverter I will not buy inverter. inverter ACs have more moving parts / circuits and other advanced mechanism compared to a regular AC. Till everything goes smooth its good, but if any issue occurs, then the repair costs of inverter are usually more than regular AC. Companies can sell the product at any rate. Really in most markets there is a clear difference of around 6-10k or even more between a regular AC and inverter AC. At your end you are somehow getting both products at same rate not sure why such a huge difference, but just this month my friend was checking different ACs and lowest price got from Sharp for Inverter was 49k! Highest was 54k. Regular 5 star for 39k-43k. So somewhere down the line the machinery is costing extra and hence you are bound to pay extra once its up for repairs / maintenance.

 

[RishiGuru]

Don’t know much about this year, but last year people in Calcutta was having the 1.1 Ton Sharp Inverter at 31 ~ 32K with full installation kit. After comparing this price with 5 Star ACs form other renowned Japanese brands it all ended up in having similar pricing. So I believe in this scenario going the Inverter way was a wise decision for many forum members.

Of course if you start comparing the price of an Inverter AC from a Japanese manufacturer with some indigenous AC companies who basically sell rebadged 5 star Chinese ACs, then these Chinese ones are always going to come cheaper. But then again they will never able to match the product quality & engineering precision of their Japanese counterparts let alone longevity.

Finally what makes you think an Inverter AC have more moving parts than a regular non-Inverter? Can you kindly elaborate as I cannot find any?

Thanks in advance.

 

[Arjun]

Yes, if there is no requirement for inverter I will not buy inverter. inverter ACs have more moving parts / circuits and other advanced mechanism compared to a regular AC. Till everything goes smooth its good, but if any issue occurs, then the repair costs of inverter are usually more than regular AC. Companies can sell the product at any rate. Really in most markets there is a clear difference of around 6-10k or even more between a regular AC and inverter AC. At your end you are somehow getting both products at same rate not sure why such a huge difference, but just this month my friend was checking different ACs and lowest price got from Sharp for Inverter was 49k! Highest was 54k. Regular 5 star for 39k-43k. So somewhere down the line the machinery is costing extra and hence you are bound to pay extra once its up for repairs / maintenance.

I was quoted 45k for sharp 1.5 ton last week without any bargaining by vijay sales, after i bargain i will get it down to about 41k, last year i bought sharp 1.5 inverter for 39k , there is almost no price difference between inverter & 5 star acs, there is a panasonic 1.5 ton inverter with a MRP of only 41k .

 

[prakash14]

I was quoted 45k for sharp 1.5 ton last week without any bargaining by vijay sales, after i bargain i will get it down to about 41k, last year i bought sharp 1.5 inverter for 39k , there is almost no price difference between inverter & 5 star acs, there is a panasonic 1.5 ton inverter with a MRP of only 41k .

That is good. Which region? Because here Vijay Sales sells at close to 50k. The lowest I got was from a Sharp dealer who said he could go as low as 48k no less. Also for refernce the price includes the machine, transportation, installation kit, installation and powder coated stand for outdoor unit. Also the prices you have managed on Panasonic are also great because when I had checked for the 1 T the MRP was 41k and after discounts and installation the dealer quoted around 39k. Hence not sure why such a huge difference in pricing for different markets, and if that is really the case all must get together and try to have manufacturers implement an all India standard price.

 

[prakash14]

Don’t know much about this year, but last year people in Calcutta was having the 1.1 Ton Sharp Inverter at 31 ~ 32K with full installation kit. After comparing this price with 5 Star ACs form other renowned Japanese brands it all ended up in having similar pricing. So I believe in this scenario going the Inverter way was a wise decision for many forum members.

Of course if you start comparing the price of an Inverter AC from a Japanese manufacturer with some indigenous AC companies who basically sell rebadged 5 star Chinese ACs, then these Chinese ones are always going to come cheaper. But then again they will never able to match the product quality & engineering precision of their Japanese counterparts let alone longevity.

Finally what makes you think an Inverter AC have more moving parts than a regular non-Inverter? Can you kindly elaborate as I cannot find any?

Thanks in advance.

Yes the prices some members seem to be getting in some markets is really great. Not sure why such a huge difference.
Further, as mentioned earlier I have compared only standard branded ACs like General, MHI, Carrier, Hitachi etc. Rebranded machine prices are so low you can install 2 for the price of 1 branded in some cases!

Inverter AC works on the principle of managing the compressor. An inverter AC has a compressor which supports varied speeds (as against single speed for regular AC). Secondly, there is a brain (circuit) which does this. If that goes down, the inverter's brains stops functioning. These two components in itself cost a lot of money. What the circuit does is that it continuously monitors the temperature and compressor speed. There are lakhs of combinations possible so it adjusts the compressor accordingly.

Inverter ACs do quite well if the usage is say 10 hours or more. Hence usually ATMs, shops, banks etc would benefit by going in for inverter. Basically if your regular AC has more start / stop cycles then you see maximum benefit. If there are limited start / stop cycles with your current regular AC the benefits are quite limited and there are some specific scenarios where after installing inverter ACs people have seen a rise in power consumption. Each machine has a sweet point at which it gives max benefits but in real usage scenario one does not experience this. Also if you study the operational COP of an inverter carefully most figures you will see are in the range of around 3.1-3.2 COP (for standard output) as against 3.6-3.8 for a 5 star Machine because inverter might initially operate at higher speeds and then varied speeds so if someone claims a standard COP of say 3.5 or 4 that is at optimum output which one would never achieve in real life.

 

[6pack]

All India standard price is not possible since most states charge different amount of taxes. Plus you need to factor in road shipment charges too.
Edit: MRP already does that I think.

 

[prakash14]

All India standard price is not possible since most states charge different amount of taxes. Plus you need to factor in road shipment charges too.
Edit: MRP already does that I think.

Yes MRP would take care of it, but I am surprised how the pricing difference is close to 10k for different markets. I would estimate based on taxes, transport etc the max difference should be in the range of 1-3k

 

[RishiGuru]

Inverter AC works on the principle of managing the compressor. An inverter AC has a compressor which supports varied speeds (as against single speed for regular AC).

Understood, but where are the additional moving parts that you claim Inverters to have over regular non-Inverter? Kindly be specific with your answer.

Secondly, there is a brain (circuit) which does this. If that goes down, the inverter's brains stops functioning. These two components in itself cost a lot of money. What the circuit does is that it continuously monitors the temperature and compressor speed.

So do you think 5-star non-Inverters do not have any circuit boards, any they will still be operational if it goes down?

Also if you study the operational COP of an inverter carefully most figures you will see are in the range of around 3.1-3.2 COP (for standard output) as against 3.6-3.8 for a 5 star Machine.

Do you think the rated COP of an Inverter AC is where it operates for most of the time in its duration of operation? Inverters have variable efficiency and as the AC reaches the targeted set temperature it goes to partial throttle mode, where the COP may rise to as high as 4.5.

 

[prakash14]

Understood, but where are the additional moving parts that you claim Inverters to have over regular non-Inverter? Kindly be specific with your answer.

Well like I mentioned earlier the difference in the type of compress and the additional circuit for running the inverter compressor

So do you think 5-star non-Inverters do not have any circuit boards, any they will still be operational if it goes down?

agreed. But do try to contact and find out for yourself because there is a huge difference in pricing if your regular AC goes bad and if the inverter AC goes bad.

Do you think the rated COP of an Inverter AC is where it operates for most of the time in its duration of operation? Inverters have variable efficiency and as the AC reaches the targeted set temperature it goes to partial throttle mode, where the COP may rise to as high as 4.5.

Yes, like it has a COP of 4.5 at its best performance, the regular COP is around 3-3.1. When you average it out many instances I have found that regular ACs are better than inverter ACs in pure COP. Yes you definitely save incase you set the temperature too high like in your case you do at 29. But regularly 25 is the standard set to be considered a "cool" comfortable room. I am not an expert in this area but this is based on my experience using various types of ACs and its performance / maintenance.

Due to variable COP you will see inverter ACs till date do not have EER certification mainly because various factors are dependent based on which inverter ACs claim high EER but like I said earlier there is a sweet point at which this high EER occurs, if not its as good as a regular AC.

 

[RishiGuru]

Well like I mentioned earlier the difference in the type of compress and the additional circuit for running the inverter compressor

Different type of compressors in Inverters & non-Inverters does in no way proves one have additional “moving parts” than the other. And for your kind information circuit boards do not have any “moving parts”. So it altogether seems you are assuming all the way that Inverter ACs has more “moving parts” in compressors without any concrete technical proof. Request you to stop assuming henceforth as your additional “moving parts” assumptions seems baseless.

agreed. But do try to contact and find out for yourself because there is a huge difference in pricing if your regular AC goes bad and if the inverter AC goes bad.

As per Sharp (one year back when I called at their service center) they said there is no huge difference in price between their 5-Star electronic module and that of their Inverter.

Yes, like it has a COP of 4.5 at its best performance, the regular COP is around 3-3.1.

Kindly elaborate what is meant by "regular" COP? It is a new term to me.

When you average it out many instances I have found that regular ACs are better than inverter ACs in pure COP.

Kindly elaborate how you reached to this conclusion of averaging the COP of inverters?

Due to variable COP you will see inverter ACs till date do not have EER certification mainly because various factors are dependent based on which inverter ACs claim high EER but like I said earlier there is a sweet point at which this high EER occurs, if not its as good as a regular AC.

In India EER certification is only provided to non-Inverters. Inverter ACs are new to our country and it will take time to implement any certification from our government. Even first world countries like Australia have just started to implement certification for Inverters. Here is what their gov site has to say:

Why don’t ‘inverter’ type air conditioners get a higher star rating?

Ans: For standard air conditioners (which use single speed compressors) the efficiency does not vary significantly at part load – reduced load output (heating or cooling) is achieved by the unit turning on and off through the thermostat or temperature control system.

Inverter units use a variable speed drive in the motor system that drives the compressor. While these systems tend to look less efficient at full load (i.e. their star rating at rated capacity, which is the rating on the energy rating label, is not always as high as conventional air conditioners), they tend to be very efficient at part load operation, which is a more common mode in a typical household.

This is achieved by reducing the continuous compressor output which increases the efficiency of the refrigeration system (as the apparent size of the condenser and evaporator is larger). Performance does vary between models, so the actual part load performance of inverter units should be sought from manufacturers. Inverter units are now marked on the air conditioner energy rating product listing and part load efficiency data is also available for some inverter models.
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Link:http://www.energyrating.gov.au/resources/help/frequently-asked-questions/air-conditioners/

 

[prakash14]

While these systems tend to look less efficient at full load (i.e. their star rating at rated capacity, which is the rating on the energy rating label, is not always as high as conventional air conditioners), they tend to be very efficient at part load operation

There lies my answer to the query. This proves that what I have been saying is right. At full load the energy rating is not as high as conventional air conditioners. Hence, only if you run the inverter AC at say higher set temperatures or say long durations, once the room completely cools down you will start noticing significant differences. Hence only places which use AC for long durations and more months in a year can benefit from inverter AC. Otherwise it makes no sense to invest in inverter ACs. You can check 5 Star and inverter specifications of major manufacturers and you will find that 5 Star has higher COP rating while inverter in most cases has lower COP rating. I found some to be say around 3.55-3.6 for 5 Star and around 3-3.2 for inverter ACs

Kindly elaborate how you reached to this conclusion of averaging the COP of inverters?

This is a known fact. Inverters use a lot higher power during initial stages and then gradually reduce to maintain room temperature. Hence if you calculate at start point the COP will be quite low but once you achieve the room temperature the power consumptions slowly reduces and the COP thus increases. Hence, for real usage scenario you need to average this out to get real savings.

Different type of compressors in Inverters & non-Inverters does in no way proves one have additional “moving parts” than the other. And for your kind information circuit boards do not have any “moving parts”. So it altogether seems you are assuming all the way that Inverter ACs has more “moving parts” in compressors without any concrete technical proof. Request you to stop assuming henceforth as your additional “moving parts” assumptions seems baseless.

Ok, I think you are not fully aware of inverter and non inverter technology then. I think you could discuss this with anyone and they should be able to guide you how it has more moving parts. First and basic for inverter AC is its variable speed. How is this achieved? Through an additional variable speed motor which will adjust speed accordingly and this is the first additional part. Plus there is a PCB which will specifically send commands to vary the speed. Similarly there are various differences in terms of technology between a regular and inverter AC.

 

[hotshot05]

Ok, I think you are not fully aware of inverter and non inverter technology then. I think you could discuss this with anyone and they should be able to guide you how it has more moving parts. First and basic for inverter AC is its variable speed. How is this achieved? Through an additional variable speed motor which will adjust speed accordingly and this is the first additional part. Plus there is a PCB which will specifically send commands to vary the speed. Similarly there are various differences in terms of technology between a regular and inverter AC.

There is no additional motor. Normal AC's use a different motor, inverter AC's use a different type of motor. The normal AC motors get either full voltage(ON) or no voltage(OFF).
The motor of an Inverter AC gets variable voltage which is governed by the controller. I don't know which modulation scheme is used. They can use PAM(Pulse Amplitude Modulation) or PWM(Pulse Width Modulation). PWM is easier to generate since it is a variation of ON-OFF scheme. There are other modulation schemes too.
https://en.wikipedia.org/wiki/Modulation#Pulse_modulation_methods

Since the name of the AC is Inverter AC, I assume that single phase AC is converted to DC. From that DC, it is again converted to multi phase AC(3ph or more). In power electronics, an inverter is a device which is used to convert DC to AC.
https://en.wikipedia.org/wiki/Power_inverter

EDIT: As per wikipedia, the compressor motors of inverter AC's use variable frequency drives. So instead of varying voltage, they vary the frequency of the AC generated from DC. Normal AC is supplied at 50Hz. Using power electronics, frequency above 1000Hz can be generated.
Speed of induction motor (N) = 120 * f / P [f = frequency of supply in Hz, P = no of poles of the machine]. Since poles are fixed, by varying frequency, speed of the rotor can be varied.

 

[Crazy_Eddy]

First of all you should learn to respect views of other members. The way you are speaking is too rude to even really respond.

Sorry about that, please ignore him or report his post and one of us can clean up his posts.

You can ask this to any person having technical knowledge and he will agree, that if your AC is correctly sized, do not use for longer durations then a regular 5 star AC is as good as an inverter AC.

This is very true, but this also explains why an inverter AC is useful. The way to size an AC is to calculate the heatload. But its impossible for the heatload to stay consistent for any room. The heatload doubles just by a doubling in temperature difference between the inside and outside temps. Lets say your inside temp is set at 27C and ambient is 30C (3C temp difference), and your heatload calculations say a 1T AC is appropriate. Now lets say the ambient temp rises to 33C (6C temperature difference), your heatload calculations will also double and you would need a 2T AC. You will have to size the AC to the maximum requirement so that it functions under all conditions. So how do you size *one* AC when the heatload requirements vary so much with just changing ambient temperatures?

Also if you study the operational COP of an inverter carefully most figures you will see are in the range of around 3.1-3.2 COP (for standard output) as against 3.6-3.8 for a 5 star Machine because inverter might initially operate at higher speeds and then varied speeds so if someone claims a standard COP of say 3.5 or 4 that is at optimum output which one would never achieve in real life.

You can check 5 Star and inverter specifications of major manufacturers and you will find that 5 Star has higher COP rating while inverter in most cases has lower COP rating. I found some to be say around 3.55-3.6 for 5 Star and around 3-3.2 for inverter ACs

While I agree with your campaign that Inverter ACs have their appropriate place, I suggest you to stick to consistent figures to prove your point.
The 5 star rating update this year requires a minimum of 3.5 COP. While hopefully this will pressure inverter AC brands to step up their game, I'm pretty sure most of brands haven't yet gotten in line with current 5 star requirements. Unfortunately I've not been able to access the BEElabel site for days to see who all are making the cut. Only the Godrej you linked to has aced the 5 star rating. The Vestas you mentioned is 3.3. If you are aware of any other models, feel free to include.
Also AFAIK, apart from Sharp, no other Inverter manufacturers are using weighted COPs to boost their spec sheet.

 

[prakash14]

@Crazy_Eddy : Most companies now have 5 Star as per new site. Verstar site does not mention it but they have already started marketing their new range of 5 Star as per 2014 which has a COP of over 3.5 even for their 2 T AC!. Other than Godrej, even Midea, Carrier, Mitsubishi Heavy, General have all launched new range of 5 Star ACs.

I have nothing against Inverter ACs and I am myself using one but the purpose rather than power savings was longer duration of use at a constant temperature. People simply jump into new "terms" and shopkeepers sell what company asks them to sell without even considering your requirements. But there are some genuine shopkeepers who explain the entire thing in detail. And the above data I presented was based on interaction with a few sellers who took the pain to explain that inverter was not required and why. (And actually I had gone to book a new inverter AC!) But when I was presented with all the details, I found out that in some cases a regular 5 Star costing + running works out cheaper than an inverter. Inverter will only start its magic once a set temperature is attained. Like I have my Sharp inverter and when I set a temperature of 25, it takes close to 2 hours to attain the temperature and during that time the display shows 1.6 - 1.8 in the display which means its running at its peak for those 2 hours. Once it does that it fluctuates at around .6-.9 and of and on goes above that too. So savings if any are hardly noticed because I shifted from a 3 Star (2.7 COP) to the sharp and I hardly notice any change in my electric bills even though the old AC used to run for more hours than this!

Also like your rightly pointed some manufacturers like Sharp are using Singapore based EER method. So in regular COP though they mention a high EER if you check it out at highest point the EER works to around 3.15 which is close to a 3 Star AC! But when the calculated the weighted average, the figure looks a magical 4. something.

 

[Crazy_Eddy]

And the above data I presented was based on interaction with a few sellers who took the pain to explain that inverter was not required and why.

Most likely these sellers did not have an Inverter AC in stock.

I found out that in some cases a regular 5 Star costing + running works out cheaper than an inverter.

Yes with 2 hour per day running you won't see a difference. I think this is sort of obvious, and I sympathise with you, but you should've done the calculations before heading out to the shop
If I buy a hugely efficient diesel car and drive 2km a day and say I'm not seeing any savings - is the product at fault or is it me? Your savings multiply based on usage. An AC cannot save money while it is turned off!

it takes close to 2 hours to attain the temperature and during that time the display shows 1.6 - 1.8 in the display which means its running at its peak for those 2 hours

Sounds like something is wrong with your AC if its running over-spec for 2 hours and/or you have undersized the AC for your room. Please check ASAP.

So in regular COP though they mention a high EER if you check it out at highest point the EER works to around 3.15 which is close to a 3 Star AC

As mentioned above, this highest point is when the AC runs over-spec and its supposed to do so for a few mins at the most. If you want to compare a 1.5T ac with another 1.5T ac, it makes sense to compare EER ratings at 1.5T, not at over-spec.

 

[prakash14]

Most likely these sellers did not have an Inverter AC in stock.

Actually it was reverse. Inverter was available off shelf at these sellers. But I had to wait for a week for regular AC to arrive

Yes with 2 hour per day running you won't see a difference. I think this is sort of obvious, and I sympathise with you, but you should've done the calculations before heading out to the shop
If I buy a hugely efficient diesel car and drive 2km a day and say I'm not seeing any savings - is the product at fault or is it me? Your savings multiply based on usage. An AC cannot save money while it is turned off!

Yes, I agree some calculations change with change in usage pattern. But like some members say only inverter is good and that too only from a specific brand is totally wrong. Based on each individuals requirements, the product also changes. There is no set product for everyone. I have been using inverter and quite happy with it. Like I am with my regular AC.

Sounds like something is wrong with your AC if its running over-spec for 2 hours and/or you have undersized the AC for your room. Please check ASAP.

Well the AC was suggested by the dealer itself. They have come in for 3 services and mentioned this and they say that if I want to reduce my bills then after an hour or so shift to L1 or L2 mode then power consumption will drop. In auto mode I hardly see any difference.

As mentioned above, this highest point is when the AC runs over-spec and its supposed to do so for a few mins at the most. If you want to compare a 1.5T ac with another 1.5T ac, it makes sense to compare EER ratings at 1.5T, not at over-spec.

Yes, provided both run at same rate. Like when you say that each time regular AC starts up it consumes additional power, in the same way if an inverter AC is running at higher load, its not our lookout as its consuming more power, so it means poor performance for that duration, like it is for a regular AC when it starts up.

 

[RishiGuru]

And the above data I presented was based on interaction with a few sellers who took the pain to explain that inverter was not required and why.

So it seems all you observations are based on the interaction with sales representatives. Those are the last persons in the world I trust. Most probably they have high incentive to push sale some non-Inverter AC of some specific brand.

Like I have my Sharp inverter and when I set a temperature of 25, it takes close to 2 hours to attain the temperature

There is something seriously wrong here. Oversized room or some gas leak. Check it out. My Sharps takes max 15 mins to attain 25 degrees. What is the model no of your Sharp Inverter?

There is a reason why Inverter ACs operates at maximum capacity during initial startup when their COP goes lower than their rated COP. It is because to cool the room faster so that it can reach the set temperature faster and start operating at the sweet sport which is under partial throttle mode. During the 1st hour of operation with an inverter AC set to say 26 degrees, the full throttle mode will be applied first few minutes after which it will operate at its rated capacity for the next few minutes. Then say for the rest 50 mins it will be under partial throttle where the COP will rise substantially.

Ok, I think you are not fully aware of inverter and non inverter technology then. I think you could discuss this with anyone and they should be able to guide you how it has more moving parts. First and basic for inverter AC is its variable speed. How is this achieved? Through an additional variable speed motor which will adjust speed accordingly and this is the first additional part. Plus there is a PCB which will specifically send commands to vary the speed. Similarly there are various differences in terms of technology between a regular and inverter AC.

Holy cow!!! Where did you gather this info. Can you kindly elaborate?

 

[Crazy_Eddy]

Like when you say that each time regular AC starts up it consumes additional power, in the same way if an inverter AC is running at higher load, its not our lookout as its consuming more power, so it means poor performance for that duration, like it is for a regular AC when it starts up.

When a regular AC starts up, it doesn't cool at rated capacity till the heat pump reaches steady state; during this process the EER starts at close to 0 and then reaches rated EER. As per your logic, can we define a 5 star ACs EER as close to 0 or do we use the steady state EER as companies do?

So it seems all you observations are based on the interaction with sales representatives. Those are the last persons in the world I trust.

Yeah but when a sales guy said Sharp uses MHI compressors, you were quick to embrace it

 

[Arjun]

When a regular AC starts up, it doesn't cool at rated capacity till the heat pump reaches steady state; during this process the EER starts at close to 0 and then reaches rated EER. As per your logic, can we define a 5 star ACs EER as close to 0 or do we use the steady state EER as companies do?


Yeah but when a sales guy said Sharp uses MHI compressors, you were quick to embrace it

He didnt say sharp uses MHI,[DOUBLEPOST=1399314258][/DOUBLEPOST]http://www.techenclave.com/communit...-more-pics-on-pg-3.164540/page-2#post-1942361