marine air
- Thread starter TWSLPS
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It depends on the freon pressures in the system.
There are 2 guys I know that live aboard at my marina that can use their reverse cycle units all winter long (NY Harbor).
I think my units manuals state it stops when water gets down to the 40's.
There are 2 guys I know that live aboard at my marina that can use their reverse cycle units all winter long (NY Harbor).
I think my units manuals state it stops when water gets down to the 40's.
I believe it would depend on the efficiency of the unit. Any unit that would drop the water temperature by removing its heat to or below its freeze point, 32 for fresh and 28 for salt at sea level, would have difficulty circulating enough water to continue to operate. Until that point they do work.
Mine also says 40 degrees. It has been nice to have since I am now living on the boat and it is freakishly cold here in Melbourne, FL. Just my luck, I move here, and the same week the next ice age starts. Damn you Al Gore...
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I hope he has to shovel snow off of his driveway tomorrow morning! [:-eyebrows]
40 is usually the cut off .. If the boats already warm it work in alittle colder water ... If the boats ice cold and water temps close to 40 ur out of luck. U can always use a small electric heater to jump start things.
Rob
Rob
My CruiseAir units that are 3 years old the manual says 40 degrees. If you buy units with heating elements they will turn off the compressor and turn on the heat strip but your fairly limited most are small heat strips. We have small electric heaters we use one on each 30 amp AC leg to help.
Bill
Bill
Those systems have a limit to the difference in temperature they can generate between input air and output air. Generally about 40 degrees. It takes a lot more power to heat air from 30 to 70 that to cool air from 90 to 75 so they may be better at cooling to a comfortable temperature than heating.
Just because a heat pump is in a boat why should it quit working below 40 degree?
The heat pump unit on my house works down into the 20's and below when necessary. It would like for the auxillary heat strips to be turned on below 27 deg. but it is not necessary.
George
G: the way i see it is that the available heat in 40 degree water is much less than 50 degree water so the system just cant process enough water to extract heat from colder water fast enough. They dont stop working just loose the ability to raise temps as high as we would like. It is 38 degrees outside and my heat pump is going almost constantly trying to keep the house at 70.
Right now it is 25 degrees outside.
I do not have the heat strips turned on and the heat pump in on a cycle of about 25 to 33 percent. Heat pumps operating in liquid (water) are supposed to be more efficient because of the higher mass of water.
I still see no reason for a marine heat pump to be less capable than a house heat pump. Certainly either heat pump is not going to produce as much heat when the air/water temperature is below 40 deg. as it will when the air/water temperature is higher.
A marine heat pump should be just fine for all conditions in which you can inhabit your boat. If the water temperature gets below 32 degrees I doubt that you will be on your boat.
Now all of this is theoretical. In reality it may be that the marine heat pump is designed so small for the marine cooling requirement that it just does not have the reverse cycle capacity to operate very well as a heating unit.
George
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Mine always worked pretty well in the winter, but winter water temps in NC were in the mid 40's at the coldest. Even a home unit starts becoming progressively inefficient as the air temp drops below about 25deg. Right now it's 17deg and my home units are cycling into defrost mode every hour and the heat strips are coming on/off to maintain the set point. Even though water is a better conductor, the air exchange area on a home unit is much larger, that along with the fan to assist in exchanging air I would think makes the home unit work better at colder temperatures.
----UPDATE----
Water temp at the slip at noon today (1/10/2010) was 34.5 degrees. Ice around the banks and near the launch ramp. Unit had shut down due to low suction pressure. Because I only get to the boat once per week, I can't say what day this happened. I have the system powered down at the breaker and am running aux heat. I have to go to D.C. for a few days. I am going to check it again on when I get back. Cabin temp 62*F on departure. I am sure it gets very cold in there at night though.
As a side note, the stuff in the fridge froze which tells me there is not a lot of insulation in the fridge itself. Fridge is shut down as well.
ER is cold but OK thanks to the Xtreme heater. I took the goldenrod heat sticks out of the ER and put one near the AC and another in the head.
More to follow.
P.S. It is NOT supposed to get this effing cold in central VA.
Water temp at the slip at noon today (1/10/2010) was 34.5 degrees. Ice around the banks and near the launch ramp. Unit had shut down due to low suction pressure. Because I only get to the boat once per week, I can't say what day this happened. I have the system powered down at the breaker and am running aux heat. I have to go to D.C. for a few days. I am going to check it again on when I get back. Cabin temp 62*F on departure. I am sure it gets very cold in there at night though.
As a side note, the stuff in the fridge froze which tells me there is not a lot of insulation in the fridge itself. Fridge is shut down as well.
ER is cold but OK thanks to the Xtreme heater. I took the goldenrod heat sticks out of the ER and put one near the AC and another in the head.
More to follow.
P.S. It is NOT supposed to get this effing cold in central VA.