HP Required for AC

[beyonder]

Does anyone know how many HP is required to run AC as well a min rpm for it to function properly?

 

[86freebie]

i had an old b210 that had 64 hp. and cooled off at idle. got really cold while driving

 

[beyonder]

Thx, but I meant minimum HP requirement, e.g. if you dissconnected the AC from the engine and hooked it upto an electric motor....what would the sizing be?

 

[holyford86]

It would depend on the size and rpm required for the specific system. there isn't really a blanket rating for ac systems.

 

[beyonder]

Ok...I have a stock compressor from a 90 4L ranger (Auto ). I am coupling this to a PM DC motor ( NOT in a ranger...lol ). I am having trouble sizing the motor to the compressor, I have not attempted to hook it up yet because I only have 1 shot at this and then its some time to get more parts. So I don't want to screw it up...lol. Since I'm building the motor myself I just need a size to make it and my books are at home...a lil ways away...lol.

 

[MAKG]

Why would you want to do this? So you can have A/C with the engine off? You'll need a whole bunch of batteries to do that...one will drain VERY FAST.

The usual rule of thumb is less than 5 HP, but it really depends on how hot it is. Head pressures are FAR higher on a hot day than a cool day.

And it won't be very effective without a big-ass fan pulling air through the condenser.

This is an enormous can of worms. You ARE going to get it wrong the first time, just because of all the variables.

 

[Will]

I think an engine mounted AC has more power than a roof mounted RV AC. Those use about 1500 watts, which is 2hp, while running.

As ro running RPM, I would estimate 3,000rpm would be about right--if the AC pulley is 2/3 the diameter of the engine pulley and the drivetrain is designed to cruise at 2,000rpm.

I think a 5hp Briggs running 3600rpm would be perfect. If you are trying to do it electrically, as MAKG said, it will take a big, big battery bank to run it for long and prevent damage to the batteries. If you are using an AC motor and an inverter you may not find an inverter large enough to start such an electric motor--which would require a fairly long surge load around 7X the amp draw of the motor.

 

[superdave1984]

Are you trying to put A/C on a golf cart or something? Like MAKG said, it's gonna kill your battery. And it may be more the torque of the motor than the HP. A good compressor is difficult to turn.

 

[beyonder]

Why would you want to do this? So you can have A/C with the engine off? You'll need a whole bunch of batteries to do that...one will drain VERY FAST.

The usual rule of thumb is less than 5 HP, but it really depends on how hot it is. Head pressures are FAR higher on a hot day than a cool day.

And it won't be very effective without a big-ass fan pulling air through the condenser.

This is an enormous can of worms. You ARE going to get it wrong the first time, just because of all the variables.

Why, because I need to cool a small room. And I dont have access to more common wall units here.

Battery bank is no big deal, I have 100KW continuous AC with a 50KW DC output w/100KW DC reserve. So power is no problem

Big ass fan I can do. I'm in a pinch, need to cool the room without off the shelf components...like a wall mount AC ( Which I'd prefer to use )

5HP, is this as in peak like an ICE or continuous as with an EM?

Can of worms? I dont follow...plz explain.

 

[Dishtowel]

Why, because I need to cool a small room. And I dont have access to more common wall units here.

Battery bank is no big deal, I have 100KW continuous AC with a 50KW DC output w/100KW DC reserve. So power is no problem

Big ass fan I can do. I'm in a pinch, need to cool the room without off the shelf components...like a wall mount AC ( Which I'd prefer to use )

5HP, is this as in peak like an ICE or continuous as with an EM?

Information like this ^ can prevent over the top reactions like this, lol

Why would you want to do this? So you can have A/C with the engine off? You'll need a whole bunch of batteries to do that...one will drain VERY FAST.

The usual rule of thumb is less than 5 HP, but it really depends on how hot it is. Head pressures are FAR higher on a hot day than a cool day.

And it won't be very effective without a big-ass fan pulling air through the condenser.

This is an enormous can of worms. You ARE going to get it wrong the first time, just because of all the variables.

 

[beyonder]

True, but the original question was how many HP to run an AC compressor from a ranger. Why and where I'm doing it is irrelevant. But they answered my questions so thx guys.


The only one I have left was whether or not the 5HP was Peak ( as with an ICE ) or continuous ( as with an EM )?

 

[MAKG]

Depending on humidity, you may have a substantially easier time making an evaporative cooler. At least until you can get that wall unit shipped. These are A LOT simpler, needing no pressure regulation, among other things. A good one will have a heat exchanger, though you can do quite a lot just by blowing a fan through a soggy sheet of linen or even just misting water into the air.

First rule of thumb -- never engineer what you can buy. It is NEVER as reliable. R-134a is an irritant, and you don't really want to blast it into a room because your electric motor was out of alignment with the compressor and killed it (for instance), especially if there is the possibility of sparks or flames (then, it becomes toxic). And keep in mind that mistakes in your installation can, in the worst case, make it a bomb. There are a lot of ways to screw up.

I doubt using a mobile A/C in a fixed location is legal in Canada, though I suppose it might be.

And I'll say it again. The power you need is a function of the outside temperature (and humidity). If you can say what the "peak" temperature is, then you might be able to guess at the peak power.

RBV air conditioners do not run continuously. They are pressure-cycled fixed orifice tube systems. It is VERY important for you to understand how this works before building something with it.

 

[ForOffRoadDriving]

see if it werent for rangers, people wouldnt come up with such creative ways to live cool on the cheap or kill themselves for next to nothing. but i think if you have put enough thought into converting your ranger ac into home ac, you must know what youre doing, more so than most. when you figure out how to heat your garage with 2.9l water pumps and single core raditors send me a PM.

 

[LearjetMinako]

I'm going with MAKG on this. Why build something that can be bought already made. Have you ever consider a portable A/C unit?