Education needed on boat heat
- Thread starter ALKA2710
- Start date
Just the same...... But different!
Actually, the system works just like a home heat pump but uses water as a source vs. air.
When in heat mode, the unit extracts heat from the cold water. Don't know how.....but it works.
Actually, the system works just like a home heat pump but uses water as a source vs. air.
When in heat mode, the unit extracts heat from the cold water. Don't know how.....but it works.
It's a reaction with the compressed Freon gas as long as the water is near 55 or above like 35 heat will work well. My boat is in Lake Erie,I have a heat pump and it works great. I'm also an Engineer and understand the gas cycle to really understand how it works is more than I want to type, but it does, think about it like an AC running backwards.
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AC pumps heat to the cooling water, warming the discharge, from the cabin air. Reverse cycle pumps heat to the cabin by removing heat from the cooling water by chilling the discharge water. Below 40 degrees F the cycle is less efficient than resistance heat and you run the risk of freezing the cooling water coil.
There is a long time RO on this site that uses marine AC in his home to heat his pool and cool his house with one energy cost.
There is a long time RO on this site that uses marine AC in his home to heat his pool and cool his house with one energy cost.
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Heat from 0°F air because it won't freeze. Just not from water which will. Resistance heating still gets more cost effective below something like 45°F.
Using your air conditioner to heat the pool works but not everywhere. In Key West when you really need the air conditioning, the pool is already warm enough. You can't run very long before you can boil up the spiny lobsters. In NJ there were only a few days when the pool heat requirement was too unbalanced with the house cool requirements.
Using your air conditioner to heat the pool works but not everywhere. In Key West when you really need the air conditioning, the pool is already warm enough. You can't run very long before you can boil up the spiny lobsters. In NJ there were only a few days when the pool heat requirement was too unbalanced with the house cool requirements.
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The basic description is pretty simple. When cooling air, the compressor takes the freon and pressurizes it and then delivers it to the evaporator which is where the cold air comes out. At the evaporator, the compressed gas is fed through a small orifice that allows it to expand. Expansion of this compressed gas is what allows it to cool dramatically. PV = RT is the old thermodynamic equation, which is pressure x volume = a constant x temperature. So you can see that if you drop the pressure and volume by allowing it to expand, the temperature will drop. This is where the AC unit converts this pressure drop to cold air through the fans by the coils. Ok?
So now, reverse cycle comes along, and what they did was add valves that reverse the flow of the pressurized gas through the coils.
The gas is compressed and gives off heat where the air handler is and it take on more heat from the compressor prior to the air handler because it was compressed and heated by the water.
That is the nickle tour, hopefully it helps.
So now, reverse cycle comes along, and what they did was add valves that reverse the flow of the pressurized gas through the coils.
The gas is compressed and gives off heat where the air handler is and it take on more heat from the compressor prior to the air handler because it was compressed and heated by the water.
That is the nickle tour, hopefully it helps.
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Chris - the refrigeration cycle involves change of phase, so the gas law doesn't apply throughout the cycle.
easttnboater
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"otherwise it would be violation of Physics, and you don't want to do that"
LOL
My brother - the nuclear engineer - talks about how the management where he works keeps asking him to violate the laws of physics and how that would be a big problem.
LOL
My brother - the nuclear engineer - talks about how the management where he works keeps asking him to violate the laws of physics and how that would be a big problem.
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The non-engineer description. When you release compressed air, it cools - or better yet, when you have a gas compressed into a liquid, and releasing it from compression turns it into a gas, it cools. Did you ever feel one of those whipped cream cartridges, or an air gun cartridge, or the valve on a propane tank as it's being used - nice and cold. That's basically how A/C works. A compressed liquid refrigerant is released into coils where it expands into a gas ( evaporates). This causes the coils to get cold. Air is blown past the cold coils, and you have nice cool air coming out. The refrigerant is then compressed again into a liquid in the condenser coils, which gives off heat. Move the warmth from compression out of the room, via sea water through the condenser, and keep the cold from expansion in the room, you have an air conditioner.
Now if you reverse the system, and compress the air in the coils that you were expanding into when operating in cooling mode, the coils are going to get hot. Blow some air past them now, and you have reverse cycle heat. The other coils, that were getting hot when you were compressing into them are now getting cold because you are expanding into them. So you have to pump water through to heat them up.
Now if you reverse the system, and compress the air in the coils that you were expanding into when operating in cooling mode, the coils are going to get hot. Blow some air past them now, and you have reverse cycle heat. The other coils, that were getting hot when you were compressing into them are now getting cold because you are expanding into them. So you have to pump water through to heat them up.
That may be how it works on land but this is a BOAT!
On a boat you buy cold air by the ton and store it in a compressor, it costs a couple of thousand buck per ton that why you see A/C systems with a higher price for more tons. When you use the cold air your money evaporates so your A/C needs an evaporator. Sometime you get excess money and the system recognizes that you have money and it will shut down and you will need to buy a new evaporator to help evaporate your money. Usually when they sell you a new evaporator they want to sell you a couple of tons of new compressed cold air in a new compressor.
On a boat you buy cold air by the ton and store it in a compressor, it costs a couple of thousand buck per ton that why you see A/C systems with a higher price for more tons. When you use the cold air your money evaporates so your A/C needs an evaporator. Sometime you get excess money and the system recognizes that you have money and it will shut down and you will need to buy a new evaporator to help evaporate your money. Usually when they sell you a new evaporator they want to sell you a couple of tons of new compressed cold air in a new compressor.
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Since the thread's been stolen already - -
True, the gas law applies to the gas side of the refrigeration cycle, unfortunately it does not apply to the liquid side - nor the change of phase (Latent heat transfer).