Air conditioner

[mrbill]

this is CORRECT shot of from a/c from cockpit


http://i5.photobucket.com/albums/y159/f ... PopTop.jpg

[Billy]

I used my AC last month in the Bahamas. I have a 5000 BTU window unit with remote I set in the companionway and run it off the Honda 2000i generator which sits in the cockpit seat. I can step over the A/C unit when entering and exiting the cabin without too much difficulty. It drains through the cockpit. I cut a plexi-glass hatch board to fit on top of the A/C unit (makes me feel better to be able to see out) and stuff some foam rubber on each side. This stores easier than a cut-out fitted piece for the A/C.

I make the Honda gen pull double duty as I also plug in the battery charger while running the A/C. (Have to keep enough juice in the batteries for the refrigerator/freezer.)

When it's time to go the next morning, I remove the panel, roll the A/C on its back to drain an excess water, and pull the quick pins from the ladder. Roll the A/C back upright and lift it with the large sail tie wrapped around it. It goes on top of a towel and slides behind the head into the "black hole". The gen goes beside it. (I only have enough gas in the gen so it will run empty sometime during the night. Dry storage.)

These units are quiet. Two of my friends paddled their dinghy over one evening and knocked on the side of my boat. I exited the cabin and looked over the side. They wanted to know if I had tried my generator yet. Were amazed it was running while we were talking. They thought the noise they heard was coming from a larger boat about 100 yards away.

A cheap A/C, but priceless when it's hot, there's no breeze and the mosquitos have decided it's time to dine. Only used it twice during the 2 weeks there, but was glad I had it. Made for a restful night.

[Frank C]

Nicely written description, Billy. I don't need one here in NorCal, but that sure seems like a perfect application of KISS.

It's good to hear that your Honda-2k handles the load while keeping the peace. Would one assume you don't have it set for the econo-mode?

[Billy]

Correct, Frank. I tried the econo-mode, but did not like the change in the engine noise when it kicked-in. I'm a light sleeper when on the boat and any change or noise usually awakens me. (Even a battery venting bothers me.) Just left it on normal and made it work. When it shut down from running empty, I slept even better. By that time the boat was really cold and morning was not far away.

[Jack O'Brien]

Billy:

I presume when not on economy mode your generator runs at a fairly steady speed. But as the A/C compressor turns on and off doesn't the generator govenor cause it to change speed and/or sound different as it works harder?

[Jack O'Brien]

Seems to me that some nut other than me with time to fiddle could make a pretty cheap air conditioner by canabalizing a car in the junk yard. A small gas (lawnmower?) engine could drive the compressor which wouldn't need to turn as fast as it does in a car at 4000 RPM. The clutch and controls and fan are all 12 VDC. Use a hose and copper tubing coil dropped in the drink in place of the condenser radiator and fan. Should be easy to duct the output air. Return air could be optional.
Would be a lot cheaper than a quiet new generator.

[DLT]

Jack,

I doubt a lawn mower engine would be quieter than the generators we are talking about...

[Jack O'Brien]

DLT:

I never said a lawnmower engine would be quiet. I said CHEAP.

One can spend $900 for a real, portable, marine air conditioner and another $900 for a 2000 watt new technology quiet generator. More than that for an installed marine air system like the big boys have.

$90 for a 5000 BTU window unit and $700 for a 1000 watt generator and you are still stumbling over them.

The junk auto system is CHEAP and could fit in a fuel locker. Could be quiet if done right.

[DLT]

I stand corrected... I misread your post...

[Frank C]

... Use a hose and copper tubing coil dropped in the drink in place of the condenser radiator and fan. Should be easy to duct the output air.

In fact, I've wondered why one couldn't just drop a hose (about 30 feet deep) into the briny and pump that fairly cool water through a heater core mounted in the cabin. It seems the pump and the fan should be amp-miserly enough to just operate from the battery - using a generator only to replenish the batteries in daylight hours .... much quieter nights that way.

I grant that pumping salt water through a metal exchanger is surely problematic ... could a mild electrical field help to defend a metal core from salt water?

Or, when is our space program gonna spin-out a ceramic or composite heat exchanger

[DLT]

You know Frank, I may just try that!

I have noticed that the lake is much cooler about about 6-10 feet below the surface. This came up before, but I guess I didn't think that pumping 80-90 degree water would be worth it. But, it is only that warm at the surface of our lake...

I have an electric automotive radiator cooling fan mounted to a hatchboard already.

I just gotta find a pump to feed a radiator core, with garden hose draped over the side... A regular bilge pump won't work because you need inlet fittings, unless you are going to toss the pump over the side too...

The only problem is going to be finding an appropriate pump with sufficient lift and low enough current draw...

Assuming 20 foot hose straight overboard, you are actually lifting the water ~20 feet. But, since ~15 of that is below the surface, the ~15 'head' of the surrounding lake water ought to negate most of the lifting...

I wonder how well this one might work...

[Chip Hindes]

Seems to me that some nut other than me with time to fiddle could make a pretty cheap air conditioner by canabalizing a car in the junk yard. A small gas (lawnmower?) engine could drive the compressor

Probably not.

It not fair price comparing something you've thrown together from salvaged junkyard parts to a top of the line $900 marine A/C and a top of the line $900 inverter generator. If you want a more realistic comparison, compare your junkyard system to an off the shelf WalMart A/C for under $100 and an off the shelf no name 2KW generator for under $400. Plug the two together and you have a fully functional (though noisy) system for under $500.

The system you've proposed is pretty much a nightmare. First, you need to find a late model A/C system in a junk yard that hasn't been totalled in an accident (an early system using R12 won't work cause you can't buy freon for it). That will not be free, it will take several hours to remove it from the car without damage, and there's usually no guarantee it worked when the car was junked. Then find a similar (and rather rare) horizontal shaft lawnmower motor. Cobble up some way to mount both and hook them together. The auto A/C is a split system of compressor/ evaporator/ condenser/ dryer which will have to be piped and hosed together. The auto system is fully integrated into the auto heating system with a series of ducts, and manual, vacuum and electric powered, dampers, doors and mixers designed to work by mixing cold conditioned air with heated air from a functional hot water heating system. Whoops! No heating system, no vacuum; how's that going to work?

A leak prone open shaft compressor which will have to be professionally serviced and recharged on a regular basis; The 12V evaporator fan will draw something like 10 amps and therefore can't be run for more than a few hours without killing your boat battery. You'll need some means of thermostatically controlling the whole mess (without the auto heater) so you get cool air without freezing yourself out. The condenser won't work without air being fan forced over it. "Throw it over the side" so it operates under water, and immersed in salt water it won't last a month.

After many, many hours of effort, even if labor is free you'll almost certainly end up with something which costs almost as much as the cheap system I described above, takes up a lot of space, but with the slight added negative that it will be highly unlikely that it will work at all.

At that point you might be tempted to run the lawnmower engine exhaust directly into the cabin and thereby put yourself out of your misery. Don't do it.

[Frank C]

... I just gotta find a pump to feed a radiator core, with garden hose draped over the side... A regular bilge pump won't work because you need inlet fittings, unless you are going to toss the pump over the side too...

Yep, I think water below some depth, maybe 20 feet, remains at a pretty cool 60 degrees or so. And that bilge pump is a great idea. You don't actually need much volume for this application since the heat transfer is relatively inefficient. Just be sure the bilge pump has a good strainer surrounding the pickup and toss it over. That keeps the pumping noise off the boat!

I wonder how long that bilge pump will survive - pretty well sealed electrics??

And, I STILL wonder how I could get it done in salt water!

[Chip Hindes]

In fact, I've wondered why one couldn't just drop a hose (about 30 feet deep) into the briny and pump that fairly cool water through a heater core mounted in the cabin.

You guys are wasting your time. In order to get sufficient cooling to get serious BTU out of a tube heat exchanger, you need a temperature difference between the ambient air and the the exchanger of at least 60-80 degrees. Even if the water you're pumping through is 50 degrees, you'll get too little cooling to make it a worthwhile exercise.

If what you're proposing had a chance of working, Coleman et al would be offering the whole system for $60.

[Jack O'Brien]

Gosh darn it Chip. Now you've gone and thrown cold water (pun intended) on our daydreams again. You wouldn't be the guy that killed my idol - Rube Goldberg - would you? Remind me not to invite you along for the ride the next time we do "The Flight of the Phoenix".

Re: The Junk Auto System

I said it would have to be a nut with time to fiddle. The fun is in the fiddling, the challenge is to do it for a lot less than your suggested $500 system, and the reward is to actually get cold air.

It would not have to be nearly as complicated as you suggest - e.g. we Floridians don't need the heater part, the vacuum and the air mixing doors. Maybe some cars have "A leak prone open shaft compressor which will have to be professionally serviced and recharged on a regular basis" but I've had good AC in cars for years without needing service.

I wrote: "Use a hose and copper tubing coil dropped in the drink in place of the condenser radiator and fan." You wrote: "The condenser won't work without air being fan forced over it. "Throw it over the side" so it operates under water, and immersed in salt water it won't last a month." Hey, it isn't a mooring weight. It isn't going to stay immersed very often or for very long. It's a coil of fairly heavy copper tubing - not a major expense if it ever did need to be replaced.

Re: The Cold Water Below System

Hey DLT - GO FOR IT. Of course it will work - it is only a question of how well. You don't need it to shrivel your cojones, only to help a bit. You might also consider a cheap submersible pump for a fountain. Some of these are 120 VAC but have an adapter, outputting 12 VDC, which you can by-pass. You are right - the "lift" needed is only the height ABOVE the water.

When I was sent to Manila in 1965 I took a 15,000 BTU air conditioner which I installed in our living/dining room. This was a 648 sq. ft. room (18 x 36) with 10-foot ceiling and louver windows on three sides. None of "The Old Hands" air conditioned anything but their bedrooms - which is where they lived unless they had company over to sweat in their soop. "They" all said I was foolish as my AC wouldn't do the job. WELL, it kept our room 10 degrees below ambient AND DEHUMIDIFIED it; and it was comfortable. And "They" were happy as hull to play bridge at our house.