No A/C when motoring? - Page 3

Brewgyver · #21 07-20-2012

Quote:

Originally Posted by deniseO30

There was a time when a 36,000 btu central air unit would draw nearly all of the 40 amps at 230 volts it was hooked up for. Now.. they run on about 9 -12 amps for the same capacity.. while they have made great strides in HP vs capacity. They still need a good share of HP to handle any kind of capacity.

This is getting a bit off topic. The current draw of any refrigeration circuit is dependent on the cooling load. The factors that determine the load include the temperature and humidity both in the area being cooled and the outside air, where the heat is being rejected. A typical 3 ton condenser (the exterior component on a typical central A/C) has a 30 amp MAXIMUM overcurrent protection requirement. Yours may be on a 40 amp breaker, but shouldn't be, and if you look in the disconnect you'll probably find 30 amp fuses. My house's 3 ton (36,000 btu/hr) condenser runs about 18-20 amps fully loaded (measured last week, with outdoor temp >100 F) , and it's 19 years old.

Brewgyver · #22 07-20-2012

Quote:

Originally Posted by night0wl

Then there's this option:

Solar Air Conditioner ***** 10,000 BTU Window Unit - YouTube

Looks pricey

It's also highly deceptive. While the base A/C unit might be rated at 10kbtu, and would deliver that while "on the grid", it's not possible to run at that load on three 180 watt solar panels. It MIGHT just be possible to run a 5 or 6kbtu unit on that supply... but even then not at full load. The 10k would require six panels, or about $3,000 for JUST the panels.

Armchair Sailor · #23 08-01-2012

Quote:

Originally Posted by NickPapagiorgio

Hi everyone,

We had my 2-year-old son with us and it was way too hot for him to take a nap down below, so he ended up being pretty miserable for most of the trip.

Anyone know why? Also, how hard would it be, or is it even possible, to rig something up to allow the A/C to run while the engine is on?

Thanks,

Kevin

Slightly offtopic. You could use towed generator also, and do "space cooling", i.e. just cool the space near the baby with a small, modern, highly energy efficient air conditioner.

deniseO30 · #24 08-01-2012

Quote:

Originally Posted by Brewgyver

This is getting a bit off topic. The current draw of any refrigeration circuit is dependent on the cooling load. The factors that determine the load include the temperature and humidity both in the area being cooled and the outside air, where the heat is being rejected. A typical 3 ton condenser (the exterior component on a typical central A/C) has a 30 amp MAXIMUM overcurrent protection requirement. Yours may be on a 40 amp breaker, but shouldn't be, and if you look in the disconnect you'll probably find 30 amp fuses. My house's 3 ton (36,000 btu/hr) condenser runs about 18-20 amps fully loaded (measured last week, with outdoor temp >100 F) , and it's 19 years old.

Eh? I'm talking in general about how much has changed since the hundreds of systems I've designed and installed, serviced, repaired, replaced, since the late 70s Not "mine" Many new machines are using 2 speed scroll comps, variable speed blowers, piston comps are slowly disappearing from air conditioning equipment.

a 19 year old machine is old from an energy use comparison even though it may be still be in good running condition. You may want to ck into a new 16 SEER 2 speed scroll comp condenser and variable speed air handler... just saying.. but it is very $$$

deniseO30 · #25 08-01-2012

NickPapagiorgio, sea frost makes a engine driven Air conditioning system BTW

travlineasy · #26 08-01-2012

Back on topic - I've spent much of the evening looking at videos on YouTube of Swamp Coolers, some of which are very ingenious. Essentially, they are all nothing more than mid-size cooler chests filled with ice with a small fan motor mounted mounted at one end on the lid, and an exhaust port at the other end. Some baffle plates inside would make them far more efficient by making the air travel over greater distances before exiting the cooler chest, but overall, they seem to work quite well and consume very little power in the process--especially those utilizing compute fans. Before heading to the sunny south for winter I intend to construct one, maybe as soon as next week. Should be fun, and if it works in Maryland's oppressive heat and humidity, it will work anywhere on the planet.

Here's one you may wish to look at:

"Cooler" Air Conditioner - YouTube

Cheers,

Gary

LinekinBayCD · #27 08-01-2012

Quote:

Originally Posted by NickPapagiorgio

Hi everyone,

I don't own a boat (yet), but we've done a fair amount of chartering on the Nothern Chesapeake Bay. Our last trip was July 6-8 during the extreme heat. The high temperature was well over 100 degrees and the wind was constantly at our back (when there was wind).

Usually, it's fairly comfortable down below when under way becuase the air temps are usually lower on the water and there's generally a pretty good breeze. On this trip however, it was just unbearable.

We had my 2-year-old son with us and it was way too hot for him to take a nap down below, so he ended up being pretty miserable for most of the trip.

Anyway, I was wondering why you can't use the engine to power the A/C like in a car. The boat we had out was a Catalina 350, but as far as I know, most, if not all, sailboats are set up so that the A/C is only operational if plugged into shore power or if you have an onboard generator. Anyone know why? Also, how hard would it be, or is it even possible, to rig something up to allow the A/C to run while the engine is on?

Thanks,

Kevin

Like you we did a lot of chartering on the Chesapeake when the kids were little. My fix wasn't the AC. I started chartering in Maine.

mikel1 · #28 08-01-2012

"Cooler" air conditioner video is interesting . . . like the concept, wonder how long the ice lasts . . .

Armchair Sailor · #29 08-02-2012

"Swamp coolers" work best in hot but arid climates. I am afraid that Maryland in the summer won't qualify...

If the humidity of the air is already 100%, the water won't evaporate in the cooler, so no cooling effect.

deniseO30 · #30 08-02-2012

Legionnaire's Disease became infamous in Phila PA in that type of equipment. "swamp cooling" coolers are essentially a "water tower" with wooden slats that water is recirculated over. as air by fan or gravity moves over them. The wood and reservoir will get nasty.. real nasty.