OT Home A/C

Well, I have no idea about these things, but I have heard that a typical house system is "2 tons" versus a car system being "10 - 20 tons".

Like I said, I am not in the know.

Where did you get a number like that? I really doubt it could be that high considering the size of the compressor, condensor, and evaporator in a car. While the compressor in a vehicle may be capable of moving much more freon than the self-contained motor - compressor assembly typically found in a 2 ton home unit, it would take one HUGE electric motor to drive it that hard and the electricity needed to power such a motor (if you could even find one) would give it a SEER rating of near zero and you would still need a huge evaporator and condenser to get 10 to 20 tons out of it.

If they can really pump that much Freon, then I guess that I'm not either :-)

Yeah, me neither. Here's a capacity curve for a typical automotive compressor. Even at peak output, it's just a little over 2 tons:

Even with a cars blower running on full the volume of air is miniscule compared to a typical homes A/C unit. The volume in a car is pretty tiny.

Try running only the front A/C in a large SUV such as a Suburban or even a mid sized such as a Durango. The back passengers will complain loudly. A house is a bit larger than an SUV in volume!

Maybe, dumbguy. Edith's talking about change play. That transgender stuff really creeps me out.

Unless you're making brownies...

mac

Please remove splinters before emailing

Mmmmmmmmmmmmmmmmmmmm Brownies!

tons:

Ok well i'm thinking the guy was probably FOS now that I discuss it with you guys, but .. "supposedly" the setup was with a Delco A-6 compressor and with R-12. He said he used a 3 horse electric motor to spin the thing... too bad he didn't have pictures to prove that this wasn't just some BS fabrication.

There's another indicator that something's not quite right with that story. Automotive AC compressors eat up a lot more than 3HP when they're engaged - somewhere in the 10-15HP neighborhood. Now, you could spin one with a 3HP motor, but it would be at a much lower RPM. As the graph showed, the lower the compressor turns, the less cooling capacity it has.

Let's assume that it takes 12HP to turn this particular compressor at

3000RPM, where it's producing right around 2 tons of cooling (24,000 BTU). That means the torque component is 21ft.lbs (12HP=3000x/5252, x=21). With a 3HP motor (that's actually capable of putting out 3HP - most electric motors are in the high-80's to low-90's efficiency rating), it would only be capable of turning that load at 750RPM (3HP=21x/5252, x=750). At 750RPM, the compressor has about 8,000BTU's of cooling capacity (reference the chart previously posted).

So, 8000BTU's is your basic bedroom air conditioner. Looking up one of the popular models, an 8000BTU window AC unit draws 7.5 amps at 115VAC, or about

860 watts. That 3HP motor above is drawing over 2200 watts (1HP=746 watts), not even factoring in motor efficiency.

Given the cost per kilowatt hour, it's much better to comsume 860 watts per hour, than 2200 watts per hour.

Jesus, Tom. You crack me up. Have you ever thought about a "rewarding" career in chemistry? You'd be good at it.

:-) Craig C.

That was chemistry?

beekeep

I was speaking of his thought process not the actual post.

Craig C.

Blahhhhhhhhhhh Random Testing!

LOL

I have no idea if the guy was telling a story or not. But, I do know when Dodge introduced the 1994 trucks with 134A systems they bragged that the A/C system was capable of cooling a 1500 square foot home, FWIW.

While it may be possible, the compressor would require serious HP to spin it fast enough to accomplish it and even if you could find a motor strong enough to do it, the power bill would be astronomical.

Great answer! :)

Thanks for the explanation, indeed.

I can picture myself in the past with a treble hook in my mouth listening to co-workers' stories..

I just got my bill for last month's electricity... $7.85

All electric home, no gas. Got a well, no water bill either :)

he's talking to you about it because you are pretty much the "expert" on that type of stuff. it creeps me out too, but for different reasons, i am certain, than you.