View Full Version : Horsepower and Kilowatts

21-03-2004, 02:30 AM
In Australia, domestic air conditioners are advertised with their size stated in horsepower units. A 2500 watt cooling unit will be advertised as a 1HP unit. I can see the sense in the American practice of using the ton unit, but our use of HP seems like an anachronism.

Is this something that we inherited from the UK, or did we make it up by ourselves?

21-03-2004, 06:59 AM
I think that this wil say: a compressor of 1 HP or consuming +/- 720 W (1 HP = +/- 720 W) will extract +/-2500 Watt heat at an evaporating temperature of 0C.

21-03-2004, 02:35 PM
hi baker,

the same over here, all domestic units advertised with HP.

I think it is so because most people are thick.
you come to a house and offer a machine with output of 12000 btu or 1 ton or 3500w, how can they tell what are you trying to sell them.

HP goes well. they think they know. what they dont know, is that one company gets 9000 btu out of 1HP and another gets only 8200 btu out of the same compressor.

we know that, but imposible to explain.

I belive thats why.

chemi :)

22-03-2004, 11:22 AM
Hey baker,

In NSW (possibly aus wide now?) it is against the law to advertise or sell a unit based on horsepower.

This is most likely because of the new power saving laws and false advertising taken by cheaper brands... for example 2 units both rated at 2.5 hp. one has a cooling capacity of 7.4kw, the other say 8kw. which one would you rather? if the prices were the same or a few dollars here or there... most people would not know the difference and say 2.5 horses is 2.5 horses...

the word you were looking for chemi is more ecconomical, on the old electricity bill - or just tell them better or newer technology ;)

just possibly?

23-03-2004, 09:17 AM
I'll bet that the units rated in horsepower originated in the far east, China, Japan, Korea etc. These units will probably also be rated in btu.

My understanding of the Asian preference for horsepower rating is that it originated as a measure of compressor capacity. We see it sometimes used in the UK by Japanese manufacturers as a measurement indicating an approximate capacity of unit.

Official rating conditions for small unitary end split air conditioners are laid down in international standards (ISO DIS 5151) and in Europe in EN 255 and 814. All these ratings are given in kilowatts.

My favourite unit conversion package, Calc 98, lists no less than six different horse powers to choose from; one is a boiler rating that converts to 9805 Watts, while most others hover around the 740 Watts mark.

It's fair to say that horsepower as a measure of refrigeration capacity is not a precise subject??.

KiloWatts and Celsius for me every time.
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