Start up an AC unit

[NoJosh]

The AC unit is dimensioned according to some specific design load. But what about in the start up phase how does the unit compensate for the high start up cooling load in the room. For example if the design load is about 20 deg C under the real temp in the room under start up.

NoJosh

[The Viking]

Hmm,
Apples and pears my friend, apples and pears...

20ºC is a temperature, not a load.

The load is the heat gain in to the room you are looking at, the total capacity of your system should be the load + the duty needed to reduce the temperature of the room from XºC to YºC. When your system reach temperature Y it will either cycle ON/OFF or reduce it's speed to match the duty needed.

:cool:

[NoJosh]

oh sorry seems like i mixed to completely different things. So will there not be a point in a system where the TD on the evaporator side will be higher than what you designed it for, and thereby creating too much superheat. With capillary tube where there is a fixed amount of liquid flowing.

[NoJosh]

Or is it a self balancing system that adopts to the sorroundings?

[Jeremy Martin]

If it's a fixed orifice (i.e. piston, cap tube) system the superheat will be high when room temp is high. You can't do a proper startup on a piston system until the room is close to design temp.