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Old 21-05-2018, 04:36   #1
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LP AC

I am considering AC options and want to know if anyone has explored LP? Airstream used to have LP AC units. Further I really like what I read about LP freezers with no moving parts.

Gas Refrigerators powered by only Propane Gas or Natural Gas

I have plenty of roof top space and tons of storage capacity for LP.

What I don't like or have is a big generator to run a typical AC unit.
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Old 21-05-2018, 04:47   #2
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Re: LP AC

It looks like you have a trimaran, so it might work better for you than for many. The problem with LP fridges and a/c on boats is that they are very sensitive to motion and/or being off level. They work great in homes, or on RVs where you park, level the RV, and then fire up the fridge or a/c. Not so good on boats that rock back and forth, or pitch up and down.

I definitely wouldn't put one on a monohull. With a trimaran I would say it is kind of a crapshoot. Maybe it will work, or maybe it won't. Up to you whether or not you want to spend the money to find out.
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Old 21-05-2018, 13:25   #3
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Re: LP AC

Quote:
Originally Posted by denverd0n View Post
It looks like you have a trimaran, so it might work better for you than for many. The problem with LP fridges and a/c on boats is that they are very sensitive to motion and/or being off level. They work great in homes, or on RVs where you park, level the RV, and then fire up the fridge or a/c. Not so good on boats that rock back and forth, or pitch up and down.

I definitely wouldn't put one on a monohull. With a trimaran I would say it is kind of a crapshoot. Maybe it will work, or maybe it won't. Up to you whether or not you want to spend the money to find out.
Thanks I knew there had to be a good reason I don't see them. It would indeed be an expensive experience if it doesn't work. They used to cool train cars and they certainly pitched and rolled a little too. Further the main area I will use it is in the Phuket area with quite calm waters.
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Old 21-05-2018, 14:09   #4
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Re: LP AC

A friend of mine had an LP fridge on his trimaran and loved it.
He used a small heat exchanger to use the exhaust gas to heat water as a by product.
Would think similar would work for AC but would need larger amounts of LP I think.
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Old 26-05-2018, 15:31   #5
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Re: LP AC

Thanks for all the feedback. I think I may have found the nearly perfect solution.

https://www.revisionenergy.com/solar...water-heating/

It is a solar powered hot water heater that uses a heat pump to remove heat from the ambient air.

With this single device I can:

#1 Cool my vessel
#2 Heat hot water for domestic use
#3 Dehumidify
#4 Use hot water to regenerate a refrigerate for my refridge
#5 Discharge excess heat using a heat exchanger

To run this much load I would need to add some more solar PV on the back of my vessel since I only have 900 watts on the pilot house currently.

Even if I had to ship this from the USA, the total investment would be lower than all the typical individual components. Further, I would require no fuel to run a generator, and no LP to run the regeneration for the air conditioner.

Further, this eliminates the worry of LP.

The one downfall is holding capacity to keep the boat cool on a hot night. Fortunately, the sun goes down at night when the PV are off so perhaps the boat can be overcooled late in the afternoon.

One issue I anticipate is having to close the engine room door to prevent overcooling of the engine. A cold engine would attract moisture.

Anyone see an integrated energy solution like this on a vessel?
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Old 27-05-2018, 14:55   #6
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Re: LP AC

Another reason not to use propane, it's heavier than air. Leaks settle in the bilge and wait for a spark.
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Old 27-05-2018, 16:31   #7
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Re: LP AC

I had an LP fridge in our RV, it worked, but not quite as good as one with a compressor. The level part was you couldnít leave it off level for long or it would ruin it, it was allowed to move, you didnít have to cut it off to drive for example.
These things are called absorption fridges, and worked by heating a liquid. Never have really figured out the principle, but there was a flame, and it got quite hot back there.

However an AC unit would be orders of magnitude larger than a fridge, and would I think consume an enormous amount of gas, besides the obvious safety problems, or an on demand water heater would be the ticket.
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Old 27-05-2018, 16:33   #8
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Re: LP AC

OK here you go, I had forgotten they used ammonia.
Apparently they are mostly used whenever there is significant waste heat already and you can harvest this waste heat to run a fridge, but to create heat to run one is apparently not efficient.
https://en.m.wikipedia.org/wiki/Absorption_refrigerator
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Old 02-06-2018, 03:40   #9
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Re: LP AC

Well after some more digging I concluded the solar powered hotwater heat pump would simply produce too much hot water and I would have to have an external heat exchanger on top deck to get rid of the waste heat.

I am now leaning towards adding about 5,000 watts of solar to bring my solar capacity to 5,900 watts and run one 18,000 btu/hr 48Volt air conditioner split system for the front and one 12,000 btu/hr for the back.

To solve the fridge problem I am thinking of installing a small 48volt freezer that can make about 50 lbs of ice per day. Each day I would have to transfer about 25 lbs of ice from that freezer into my current fridge box.

These three appliances combined cost less than the cost of a large new LP fridge/freezer.

Further, all the extra solar would shade the back of my vessel which is the hottest currently.
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Old 03-06-2018, 10:53   #10
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Re: LP AC

Lots of panelage for a boat.

Watch out for impact on sailing performance
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Old 03-06-2018, 10:55   #11
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Re: LP AC

A small eu2000 genny will power a decent sized regular aircon, just have to watch out for the CO exhaust issue.

Most people only need aircon while on shore.
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