Hi. I'm interested in finding out if a cooling system for refrigerators or air conditioner has been developed which runs not in electricity but directly driven off a small engine (4 cycle weed wackier?).
Here in Missouri its been hot and humid. Presently running a small window unit (8000 btu) off a 2200 watt inverter generator at about 6 hours per gallon.
Wondering if a direct drive system could work and be more efficient. Any ideas?
Thanks. Tom

Running an inverter generator and an air conditioner off it is your best option for efficiency unless you want to invest some serious coin. Just be sure to run your air con full out and turn the gennie off when it gets cold, turn it on only to cycle it. No idling on gas to maximize efficiency. The marine crowd and the trucking industry both run large air cons off of engines directly. Belt driven compressors like those found in cars but more industrial. Its custom and small market so expensive. Solar could be a good fit for it just lots of panels, tiny battery and use all the juice coming out of them to run the air conditioner keeping just a little extra for an emergency power supply. Run the gennie only after the sun fades.  Extended life on the gennie and a second system for redundancy.
Cheers,  David

Recreation Vehicles have refrigerators driven by propane and are currently made, but they are nowhere near as efficient as electric refrigerators. I looked into replacing my refrigerator in my house and the cost would have been like 3 times more expensive for propane.

I am not sure about this, but a POTENTIAL work around is using ammonia in a solution. I do not know much about it except that is what they used initially to cool the ice rinks of the early part of the 1900's.

Either way, none use a small engine to power them. I know they used to make them, probably in the 1930's or so, as my neighbor's dairy farm burned down when his gas-driven refrigerator unit for his milk tank caught fire from a gas spill. But back then, before rural power was a thing, such a device was in high demand. It was before my time, but my Grandfather spoke of it.

A propane fridge in an RV is an Ammonia loop fridge. As you correctly stated they are nowhere near as efficient as a compressor driven electric unit.

Yes, car AC compressors run direct drive via a belt that connects a pulley on the crankshaft to a pulley on the compressor shaft. Maybe you can pull the whole system from a scrapyard but to work at full whack they need airflow past the AC system's radiator

I would think for cooling down a home, using some sort of geothermal way might be a better solution.

My house is in Maine where air conditioning is not required, but heating efficiently through our long winters is.  So I have extensive geothermal heat set up, yet found in the summer that same system cools my house. I could make it more efficient if I made an ice house, insulated the ice with sawdust, then in the winter let the ice freeze, and in the summer cycled water through the ice to cool my house even more, but it really does not get that hot for so long here that going through all that trouble for what little bit of comfort I would get, would be worth it. perhaps for you though, it would be? That is another direction you could take?

Think about a middle Eastern wind tower on your house I have built one

First post!

Direct drive, or "Open-drive" compressors are abundant, but not like they used to be, and generally not on the small side.  I also think a car AC compressor would be the best option for the size of the heat load.  Specifically, a small capacity York compressor, still manufactured under a different name, could be rigged up with an appropriate belt to a gas engine.  In reality, this would be a lot of work to get it working smoothly and efficiently, unless you have a lot of experience with HVACR design.  There aren't too many examples of DIY open-drive systems, because it's noisy, and impractical.  I for one love the idea of a repairable compressor, but something like this could have a lot of maintenance issues such as leaky shaft seals.  

Ammonia absorption air conditioning systems exist, but you'd better have a good source of waste heat to run them, and a deep wallet.

Off-grid air conditioning is a tough nut to crack, especially if you're seeking any semblance of sustainability.  My suggestion would be to reduce your need for AC as much as possible.  Insulate.  Exterior window shades.  Sun blocking trees.  Night time ventilation to bring in cooler air, solar chimney for passive ventilation, and maybe dig in some Earth tubes for cooler ground air.

AC is great, but it is a luxury of the cheap energy age.  Time to learn to live without.

Travis Johnson wrote:So I have extensive geothermal heat set up, yet found in the summer that same system cools my house.

Interesting... Have you got a thread or a post about this? Im looking to set up a simple geothermal cooling system along the lines of a copper coil in the ground with water pumped thru it, so i can cool a subsurface shallow dew pond. We have zero precipitation for about 360 days of the year but we have humid sea air and most nights we are tantalisingly only a couple of degrees over the dew point. If i can lose those couple of degrees underground then i should be able to condense a fair bit of water from the air...

Steve Farmer wrote:

Travis Johnson wrote:So I have extensive geothermal heat set up, yet found in the summer that same system cools my house.

Interesting... Have you got a thread or a post about this? Im looking to set up a simple geothermal cooling system along the lines of a copper coil in the ground with water pumped thru it, so i can cool a subsurface shallow dew pond. We have zero precipitation for about 360 days of the year but we have humid sea air and most nights we are tantalisingly only a couple of degrees over the dew point. If i can lose those couple of degrees underground then i should be able to condense a fair bit of water from the air...

No, I do not have a thread about it per se, I have quite a few regarding my heating system which is tied into it, but how to find them over the years of posting on here I am not sure.

I think for what you would want, I might just go with PEX since it is so much cheaper then copper tubing though, and comes in long, long lengths.

I often thought instead of using electricity though, a person could use wind power. It need not be an extensive system, just a horizontal windmill with a mechanical plunger that ran a simple diaphram pump to circulate the water in the closed loop system. Just writing that last sentence makes it seem 10 times harder then it really would be. In your case it should work, but I am not sure about the orginal posters case however. I know here, house cooling typically needs to take place when there is no breeze. I mean if there was a breeze, a person would just open the windows and cool their home that way.

Travis Johnson wrote:
I think for what you would want, I might just go with PEX since it is so much cheaper then copper tubing though, and comes in long, long lengths....

… I often thought instead of using electricity though, a person could use wind power. It need not be an extensive system, just a horizontal windmill ...

I'll consider PEX or PVC etc because as you say very cheap. I was thinking copper due to conductive properties but I guess even if I lose out ay fivefold on the conductivy I will probably gain 20 fold on cost. So using say ten times the amount that I was planning for copper I would be better off in both cost and effectiveness.


I'm going to use solar power as I'll only need at most 20W ad quite possibly get away with a 1W solar fountain. The water is circulating so it doesn't have to fight a head of water, and there isn't really an advantage in circulating at speed as faster circulation is offset by less time to exchange heat. I'm planning building it at the edge of a terrace facing the prevailing wind so the airflow doesn't need to be driven mechanically. The terrace is maybe 2 metres high with soft sand/soil so I can excavate to bedrock by hand in an hour then power drill a metre or two for the heat exchange. It's all early planning and vague, but I'm thinking simple quick start, measure results and take it from there.... I'll start a thread when I get somewhere with it.

You bet bro, bigger deal on the copper in the ground is corrosion from the underground environment.

Thanks MeTube, DC vid.
[youtube]https://youtu.be/qJyLn_8OQ0s[/youtube]

Most ground and water immersed geothermal loops are made of black poly pipe as far as ive seen.
Inexpensive and impervious.  

Yeah, those ancient egyptians didn't know shit.

Corrosion of buried copper

If the pipes they used 5000 years ago are still intact, I would wager that even modern plumbing copper would outlast PEX or PVC, especially in successive freeze/thaw cycles, except in the very specific cases mentioned in the link.

Accordingly, if you are building a more compact system, or have the money and expect the system you're building to have to last a long time, then copper's probably the way to go.

-CK

The copper pipes might still exist, but I doubt they still hold water.

My house still has much of it's original copper plumbing, but I got tired or constantly patching pin hole leaks so I replumbed with PEX.

Every house in my neighborhood started developing pin hole leaks within 10 years after they were built.  Maybe it was a bad batch of copper, maybe it's something in the water, maybe in was poor installation, who knows.

Copper is generally good stuff, some houses that are 70-80 years old still have their original copper plumbing, but this is not always the case.
Pex, that is properly installed, will probably last as long if not longer than copper.