Split Air-Con power consumtion

Hi group,

I am wondering if I leave just one unit of my 4-split air-con on, will the power consumption be the same as leaving all 4 units on?

I was thinking if there is only one compressor, then switching on just one unit, would 'take-up' the whole compressor?

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unit, would 'take-up' the

I for one do not understand what your talking about.

I have had my head in the clouds for years, so it is probably all me.

Assuming that your air conditioning compressors (actually condensors) run continuously, running only one will consume only 1/4 as much energy. This, of course, assumes that each is a totally different system.

unit, would 'take-up' the

I have no idea what your second question means.

Harry C.

Ok, LOL!

Ehh...what do u mean ' totally different system'?

Probably a stupid question coming up. Just how many condensers does a split air-con system have? I can only see one 'physical' box outside my home which all the 4 air-cons are connected to. Someone once told me that this 'box' can contain about 2 or more condensers serving different air-con units.

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Actually, it is the compressor that runs. The condensor is just the heat exchanger that rejects the heat.

It will consume less, but not necessarily 25%, since the one may see a much greater cooling load than it does when four are running, so the power into it will go up.

Ben Miller

Eh...but what if the all the 4 air-con units are in separate rooms?

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Sorry, but the box that sits on the roof or outside the home and contains the compressor is generally termed the 'condensor unit', while the 'evaporator' coil is contained within some air circulation unit inside the building.

Although somewhat true, this is a 'nit', since in a properly sized system, the compressor generally runs at full load capacity and runs nearly continuously. The humidity removal properties of the system and energy efficiency are compromised when the compressor is run intermittently, or oversized for the btu load.

I'm certainly no authority on the subject, but I have installed three different central air systems in my homes over the years, and have had the luxury of having time available to monitor the power demand of each of these systems under various load conditions. From current measurements, I've learned that the power demand by the compressor is pretty much constant regardless of temperature conditions, varying less than 2-amps with a nominal, steady-state compressor current draw of 24-amps on the systems I've owned. Monitoring system pressures with a refrigeration gauge set demonstrates that any variation on the compressor load is a result of the ambient temperature in which the condensor coil functions, and little to do with the cooling load placed on the evaporator. This justifies the need to always locate the condensor unit in a shaded location.

Based on both personal experience and reading the HVAC literature, were I to install central air on a two-story home, I'd use entirely separate systems with individual condensor units to minimize energy consumption and optimize cooling, just as is now done in many appartment complexes for a different reason.

Harry C.

Assuming all units are for the same room, which I don't believe it is the case, the one unit left on will work non-stop to keep the desired temperature down.

The net results:

25% < electrical consumption < 100% (depending on the outside temp) Premature compressor failure, that is costlier than the economy you're trying to achieve.

You are better off keeping all four running with slightly higher temp & lower fan settings when you're not home. That way the four units share the load confortably.

Tommy

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I'm not sure I would agree with that. If the continously running compressor is operating within its normal design suction/discharge pressures and temperature, it may last *longer*. Frequent motor starting is a common cause of overheating. A lot of mechanical wear happens during startup if the lubrication is self-fed. Wouldn't surprise me if it can be run continously for quite some time. As long as the condenser coils can be kept clean and it doesn't develop any refrigerant leaks.

daestrom