newbi and questions

[keachier]

Is there someone who had try automotive hvac hacking,I think parts from smashed cars some pratically new and heavy duty system that resist vibration,rust... can be good .I don,t know how much effiency can be obtained from these parts.

[Daox]

I can't say that I've seen anyone hack automotive HVAC. With the inexpensiveness of window A/C units and dehumidifiers, what would be the benefit?

[jeff5may]

Welcome to the forums! There are many differences between home and automotive Hvac systems. I'll try to shed some light on the subject, so that you can better decide how to pursue your goals.

Auto a/c systems are mostly charged with R12 or R134a. The systems operate at lower system pressures than home HVAC systems. R134a is commonly available at auto parts stores everywhere. The compressors are mechanically powered (by a belt) and are designed for constant output regardless of RPM (over a certain minimum speed), having either a discharge pressure regulator or a variable displacement mechanism built in. Most are plumbed with aluminum. As with anything automotive, the fittings and actual hard parts are all proprietary. Salvage yards charge a pretty penny for working parts, due to this proprietary nature. The designs are very forgiving, though, so if you can hack a system together without leaks and charge it correctly, it will probably work well for a long time. Overall efficiency is not stellar.

In contrast, most home systems are charged with R22 or R410. System pressures run higher than automotive systems, and the refrigerants are not readily available to the public. Luckily, some natural refrigerants are being made available for retail purchase, but ordinary barbeque grill propane is a "hobbyist" substitute for R22. The compressors are electrically powered, and most run at constant speed. The majority of home systems are plumbed with copper and use mainly universal hard parts designed for a certain capacity. In today's throwaway society, there are plenty of units being thrown away daily or sold dirt cheaply due to obsolescence. Efficiency is pretty much built in at the factory, the more efficient units demand a higher retail price when new.

[keachier]

Originally Posted by jeff5may

Welcome to the forums! There are many differences between home and automotive Hvac systems. I'll try to shed some light on the subject, so that you can better decide how to pursue your goals.

Auto a/c systems are mostly charged with R12 or R134a. The systems operate at lower system pressures than home HVAC systems. R134a is commonly available at auto parts stores everywhere. The compressors are mechanically powered (by a belt) and are designed for constant output regardless of RPM (over a certain minimum speed), having either a discharge pressure regulator or a variable displacement mechanism built in. Most are plumbed with aluminum. As with anything automotive, the fittings and actual hard parts are all proprietary. Salvage yards charge a pretty penny for working parts, due to this proprietary nature. The designs are very forgiving, though, so if you can hack a system together without leaks and charge it correctly, it will probably work well for a long time. Overall efficiency is not stellar.

In contrast, most home systems are charged with R22 or R410. System pressures run higher than automotive systems, and the refrigerants are not readily available to the public. Luckily, some natural refrigerants are being made available for retail purchase, but ordinary barbeque grill propane is a "hobbyist" substitute for R22. The compressors are electrically powered, and most run at constant speed. The majority of home systems are plumbed with copper and use mainly universal hard parts designed for a certain capacity. In today's throwaway society, there are plenty of units being thrown away daily or sold dirt cheaply due to obsolescence. Efficiency is pretty much built in at the factory, the more efficient units demand a higher retail price when new.

Many thanks for reply.
I begin to know more things, copper resist more pressure than aluminum,weight is not a concern in stationnary hvac.I know of research to put more efficiency in automotive system for fuel efficient vehicule, and more for electric cars.Hvac in a tesla vehicule must be very efficient...New developpements to come .

[jeff5may]

Auto a/c compressors are rather small in capacity, due to the small relative volume inside a vehicle. They are built as a "revolver" pistol... many small pistons inside the shell working in tandem. If you can source cheap salvaged compressors and have a free source of mechanical energy (water wheel, windmill,etc.), it would be a cheap way to cool your home. As for heating, I know it will work in theory, but haven't seen much info on the subject. Good luck.

[Xringer]

Originally Posted by Daox

I can't say that I've seen anyone hack automotive HVAC. With the inexpensiveness of window A/C units and dehumidifiers, what would be the benefit?

The last cheap window A/C unit we got from Walmart ($89) worked really well.
I was saving two of those small units for heating experiments,
but my wife has a niece that just moved into a new apartment without A/C.
It's now a very cool apartment..


Car A/C systems don't seem to be a very cost effective way to go. (Due to the mechanical power needs).
But, newer cars like the Prius C doesn't use a fan-belt off the engine..
And, I'll bet the A/C on a Prius C is pretty efficient. Find one that's been crashed.?. Might not be easy..