Why Window AC consumes more power as compare to Split AC?

Basically the efficiency of the loads (motors) especially the compressor. You might find this interesting as well as understand the cost behind high eff compressors.

Well there are a lot of factors here you leave unknown....voltage of units for one....for instance if one is 220v and the other is 110v, that would explain the discrepancy....now if we consider all things equal, then the EER rating would determine what amperage draw we would be looking for....The amps multiplied by the volts equals the watts....the BTU's divided by the watts equals the EER(energy efficiency ratio)....Which would typically be in the 10 to 16 range....this would be measured under full load, on a hot day...Now as the temperature, or load, drops, the amperage starts to drop...The first thing you have to measure is the output, to see if the unit is putting out the BTU's that it's rated at, or if there is a problem with the freon charge being low, or some other problem, such as airflow....So if the unit is drawing 14amps total(condenser and airhandler) and the voltage is 230v that would equal 3220 watts....18,000 btu divided by 3220 equals 5.59 EER, which would be too low, however if the unit is 115v, that would put it just over 11 EER which is in the ballpark....

Can't say as I can agree with you when you say, "for instance if one is 220v and the other is 110v, that would explain the discrepancy".

That just ain't so. There is little or no difference in the energy consumed at the two different voltages.

While that's true, it would explain the difference in amp draw, which was my point....While the op does mention the wattage, he doesn't make it clear how he determined that....Without the complete formula, we can't be sure of the accuracy of the data....Nor does the op mention the stated EER rating of the units or the condition, age, or circumstances under which the measurements were taken....

True. Your point is taken and we need more information from the OP.

Signode?

As SolarEagle pointed out, there are many, many things in the design of each AC unit that can add up to the difference.

The motor could be driven by a small soft starter or variable frequency drive instead of just a centrifugal switch with a capacitor for starting. The compressor design could induce less turbulence in the gas during the liquification process. Similarly, the air handler might hit the balance correct to provide enough turbulence to maximize heat transfer but still prevent icing from humid air from happening. A PID loop controller may exist in one design to better control temperatures and or humidity. Core losses in all of the motors may have been reduced. Better isolation of waste heat. Etc. Etc. Etc.

I gave an answer more geared towards a high eff ductless split didn't I? see what assuming gets you?

Some additional information about the specifics would be helpful in explaining this particular situation, but even without that, there are some advantages that split ac will have over a window unit that can lead to better efficiency, even without use of more efficient motors or controls.

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The obvious major difference between the two types of systems is the severe dimensional constraints of a window unit as compared to the relatively unrestricted dimensional constraints of a split system.

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Size, shape and orientation of the heat exchangers, the size of the blower wheel/fan blade, and the cross section and maximum curvature of the ducting are all affected negatively with respect to efficiency by the dimensional constraints of a window unit.

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Another significant factor related to dimensional constrains is the lack of separation or even much room for insulation between the handled indoor air and the heat from the compressor and condenser with a window unit layout, whereas the separation with a split unit means it would be negligible with a split unit.

TCM makes a good point about the possibility of a run capacitor being weak or bad....A quick test, if you have an infrared thermometer, is to check the operating temperature of the compressor.....unless I miss my guess, it will be running hot.....this could be due to a weak, or bad, or disconnected capacitor, or it could be due to a low refrigerant charge, or it could be due to a bad capacitor, or weak, on the condenser fan motor....so I would test the operating temperature of the motor as well....check the rotation(this can reverse in certain conditions)....In any case the amp draw I think is high, and there is a problem with the window unit....

I think TCM point isn't so much that there could be a problem with a capacitor causing the difference in current drawn, but rather that the real difference in power consumed could be much lower than the measured current would suggest.

Yes that condition would be characteristic of a failed capacitor.....sí or no...?

"....sí or no...?"

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Mu.

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A failed capacitor, if it failed in the right way, could be a sufficient condition to bring about a state similar to what is being described, but it isn't a necessary condition.

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The interesting thing that TCMs comment opened my eyes to is that no failure needs to have occurred and that the noted difference in measured current might just as easily be be indicative of differences in power factor of the original design than attributable to real differences in efficiency.

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Something tells me that yellow tooth in your grill is probably iron pyrite. ^Ba-Zing!

That would be a very poor design indeed.....can you cite any examples of window A/C's with this design, because I think they should be avoided at all costs....

I do have a nice chunk of iron pyrite.....but teeth are from Sweden....

You want me to cite examples supporting the existence of a possibility of which I have only become aware in this blog? I realize the burden of being asked to prove a negative, but you seem enthusiastic about this one, so: perhaps as an alternative you can be encouraged to cite evidence that no window units likely to still be in service were shipped with power factors sufficiently below the highest found in split units to account for the noted discrepancy beyond typical differences in efficiency accountable to the shape size.

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BTW, being from Sweden is neither necessary nor sufficient to establish something is not iron pyrite.

Very well. I claim this statement as truth...

"No window units, likely to still be in service, were shipped with power factors sufficiently below the highest found in split units to account for the noted discrepancy."

Now. claim the statement false if you can.....or admit defeat....

Defeat? I'll admit learning something new; specifically that Solar Eagle claims as truth:

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"No window units, likely to still be in service, were shipped with power factors sufficiently below the highest found in split units to account for the noted discrepancy."

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Give me a little time and I'll give you my verdict on the claim itself, and if I cannot substantiate it is false then I will abandon my original position and proclaim it defeated.

The two units being compared probably use different refrigerants, since window-type AC units are likely to be old.

But low refrigerant quantity has a dramatic effect on efficiency. See the chart here:

http://www.proctoreng.com/utilities/Charge.html

Your posting leaves to many unanswered items . . .

Please provide FULL NAMEPLATE INFORMATION on the units you are discussing, otherwise this discussion will lead NOWHERE!

The supply voltage, refrigerants and like common aspects being the same, it looks like the power consumption should be lesser for window units . Most window units have common motor for both the heat exchangers (condenser and evaporator), where as, in split units, there are two individual blowers/motors.

Those are some weird voltages you have,or a miscalculation of power.

2700 watts divided by 14 amps=192.8 volts,

and 1800 watts divided by 9 amps =200 volts.

Calculation errors aside,look at the EER of each unit,and there in may be your answer.

Every couple of years they increase the EER, so a couple of years difference in age could be the difference.

Of course,there are many other factors to consider,such as the space constraints of

the evaporator and condenser coils on the window unit,the type of compressors,scroll

or standard type,the type of refrigerant,etc..

HTRN, Not all of those Amps are "real", some are reactive and therefore don't make the meter spin. Your calculations ignore power factor which on these units can be significant, hence the "weird voltages".

As others have pointed out, the newer split units have much higher EER, some nearly double that of a window unit. Split units also have larger condenser and evaporator surface area which requires lower compressor pressures/flow rates and slower fans which contribute to lower energy consumption and higher efficiencies.

Those features are monitored with smart controllers which adjust the inlet and outlet flows/temperatures of refrigerant of both coils plus both airflows by using inverter technology to adjust the motors' speeds to meet the heat load.

These are not the window units we grew up with.

Yes it would seem the op is using a watt meter instead of a formula....Typically he should have 220v....

Here is a formula that can be used to determine capacitor size....

http://www.allaboutcircuits.com/vol_2/chpt_11/4.html

voltage of both ACs are same, 220V

I dont know about refrigerent used in both ACs.

To calculate the input voltage, you must consider the power factor as the formula of power in AC supply is

P = V X I X Cos

Both are used in the area where outside temperature is raised up to 45C.

Standard procedure, but you made no mention of PF in your OP,or how the measurement was made,with KVA meter,KVAR meter,

DVOM,amp meter,analog,digital,True RMS ,or whether the data was from data plates on the units.

So I was just taking a stab in the dark,based on limited info provided.

So exactly how was your measurement made?

Please specifiy.

Regardless,the factors I stated are still true.The EER of the system,the limited size of the Evap and Condenser coils of the window unit vs the split system,the distance separation between the evap and condenser coils,the distance of evap coil from outside ambient temperature,and compressor heat,the type of refrigerant,cleanliness of coils,etc.

Split systems are usually more efficient that even pad mounted external systems,due to distribution losses in duct work,and radiant heat etc.

An Addendum to my previous post,to the OP:

As an exercise,Google Pad mount systems, split systems,and window units and see if there is a window unit that is as efficient as a pad mount or split system.

I could not find one,you make have better luck.

Split systems are the most efficient, with pad mount second,and window units 3rd.

Even though pad mounts are not as restricted in size like a window unit,they must push the air through long duct work from the unit to a trunk line, and then through distribution duct lines,and then through the return ducting on the outside pad unit.

A split system,however, only has to carry refrigerant from the outside unit to the evaporator coil,and back to the condenser.

The evaporator coil is only exposed to the inside ambient temperature,and the evaporator coil is a long distance away from the condenser,so no radiant heat transferred from the condenser to the evaporator.

There is less static air pressure required to push the air through the shorter supply and return ducting.

I think that more or less proves the difference is in the physical,dimensional variables of the systems, and the distribution of the air.

Window AC may be inefficient, consumes more power and outdated. But it has fresh air and exhaust settings which help in improving air quality whereas in split stale air is recirculated.

Much ado about the energy draw but little about which is better, not in terms of energy savings but performance. Some designs are "efficient" others work better?

This discussion could easily equate to internal combustion engines on many levels. Gas, LPG or Diesel? Manual or automatic? 4 cyl or 12? Etc.

Then there's your location, tropical, equatorial, temperate, desert or polar? Humidity? Would the same results be true if the unit was in another climate zone? Do AC designs consider the region they will be operating in? I would assume so. Which would be harder, thereby causing the system to work more?

Cheers

Actually it's an apples to oranges comparison, the two types have entirely different design criteria. A window unit has to, duh, fit in a window, be light enough to handled in a store, not require any additional wiring, be installable by a consumer with no technical skill, and for certain markets cheap and affordable.

A split unit; has minimal space and weight constraints, is best installed with a refrigeration technician and a helper, requires installation of refrigerant lines, at least two wiring runs, control wiring, and is meant for markets where the benefits off paying up for efficiency are understood by the consumer.

The lack of size constraints means heavier, larger, and therefore more efficient motors can be used. The refrigerant lines can be larger for less resistance to flow, the condenser and evaporators can be heavier, larger, and therefore have greater surface area. The fan sizes can be bigger, slower, and therefore quieter and more efficient, plus there's room for smart controllers that manage the whole system. to maximize both cooling capacity and efficiency. With inverter technology the motors can all be variable speed AC or DC, managed to match the load, and the input power factor can be controlleded by the smart inverter thereby eliminating the need for pfcs.

I'm surprised, why no one discusses about the minimum 'number of motors' required for these two comparisons! Is not more motors mean less efficient?

I disagree on the idea that multiple motors necessitates inefficiency. On a generic basis, by breaking up multiple mechanical tasks to discrete individual processes for independent motors to handle, it makes it easier for a designer [engineer] to optimize the motor selection to the mechanical task at hand. In contrast having one electric motor handling multiple mechanical loads necessitates this motor to run sub-optimally for each and every process.

More to my point here, driving multiple loads with multiple motors offers a designer the capability to independently optimize each process. Lumping all mechanical processes to just one motor induces a compromise somewhere.

Yes, a single motor may well be oversized for one thing and undersized for the other, thats inefficiency.