I am considering adding a ductless air system on my Catalina 30.Any comments or advice would be welcomed Thanks in advance
Ductless air conditioning
- Thread starter mgraham
- Start date
Window units or thru-the-wall units are ductless. Is that what you are talking about? They are quite common on boats
Mini-split systems are ductless. But where would you put the condensing unit and refrigerant lines? And why?
Maybe you are talking about portable a/c units that have a single flexible duct to the outside? I'd say those are lousy.
An a/c unit that is totally contained indoors with no outdoor contact at all is just a silly way to heat your space.
Mini-split systems are ductless. But where would you put the condensing unit and refrigerant lines? And why?
Maybe you are talking about portable a/c units that have a single flexible duct to the outside? I'd say those are lousy.
An a/c unit that is totally contained indoors with no outdoor contact at all is just a silly way to heat your space.
Yes jwing the one that is contained indoors and has has a duct to send warm air out the hatch.I am completely out of my element but how come that won't work.Thanks for your help
I can tell you from experience with a stand up Heier 9,000 btu unit that the heat coming off the exhaust hose will roast you in the cabin! We had the hose exit out the quarter berth window and had to wrap the entire hose in foam and foil. It kept the hose stiff but did help. The stand up units will save a small fortune over a marine reverse cycle 16,000 btu unit. I strongly recommend you find the highest btu unit (11,000) or higher and you wrap the flimsy plastic exhaust hose to reduce radiated heat. Try blue foam wrap at Home Depot followed by a foil cover and duct tape. You will glad you did.
Bob
1988 mark ok
Bob
1988 mark ok
Think about this: There is a big, flexible duct that is exhausting very hot air to the outdoors. Where does all that air come from? The indoors, or in this case, your boat's cabin. Now, if air is being sucked out of the boat, that means that either your boat will become a vacuum and the a/c unit will not be able to work, or air will be pulled from the outdoors into your cabin to replace the air that the a/c unit is pushing out through the duct. That means that the unit pushes the air that it has cooled out of your boat and pulls hot, humid air into your boat.
Now lets think about all that heat - where does it come from? The a/c unit uses lots of electricity to cool hot, humid air. The heat that is pulled out of the air goes out the duct, but also all the electrical energy is converted to heat and that supposedly goes out the duct, too. Trouble is, as Bob4203 explained, some of the heat radiates and is convected out of the duct, back into your boat. Since an air conditioner actually makes more heat than it removes, the unit is always fighting itself.
Then you need to deal with all the condensate that you get by dehumidifying a constant flow of humid air passing through the boat.
All in all, those portable units are terribly inefficient and are only moderately useful if you are in the path of the cool air jet and you don't mind being in a cold draft in order to feel cool.
Window units reject heat and condensate directly outdoors and do not pull conditioned air from the indoors. They are a better choice.
Now lets think about all that heat - where does it come from? The a/c unit uses lots of electricity to cool hot, humid air. The heat that is pulled out of the air goes out the duct, but also all the electrical energy is converted to heat and that supposedly goes out the duct, too. Trouble is, as Bob4203 explained, some of the heat radiates and is convected out of the duct, back into your boat. Since an air conditioner actually makes more heat than it removes, the unit is always fighting itself.
Then you need to deal with all the condensate that you get by dehumidifying a constant flow of humid air passing through the boat.
All in all, those portable units are terribly inefficient and are only moderately useful if you are in the path of the cool air jet and you don't mind being in a cold draft in order to feel cool.
Window units reject heat and condensate directly outdoors and do not pull conditioned air from the indoors. They are a better choice.
I have to adds something Jwing might have not known and that is, these standup portable units are designed to evaporate the condensate internally. The unit I had and others we checked out did not have discharging condensate from the unit. One great feature.
With the exhaust hose going out the quarter berth port hole, which was framed in cardboard as a seal, the hot exhaust discharged out into the cockpit. The hose extended about 6 inches into the foot well of the cockpit. Nothing came back into the cabin regarding the exhaust. The system provided enough cooling and dehumidification at night to make the cabin quite comfortable.
If you are seeking only a cold cabin night's sleep, then the stand up units will do the trick, providing that the exhaust hose is insulated and discharges out the boat. If you are seeking to stay below during a hot summers day then FORGET ABOUT IT! These units just cannot keep up with the heat buildup inside. The only way to really cool down the cabin is the costly Marine AC unit. The big question for us has been: are we ready to spend over $3000 (unit, install kit and labor) to enjoy that luxury?
Bob
Lake Lanier, GA
With the exhaust hose going out the quarter berth port hole, which was framed in cardboard as a seal, the hot exhaust discharged out into the cockpit. The hose extended about 6 inches into the foot well of the cockpit. Nothing came back into the cabin regarding the exhaust. The system provided enough cooling and dehumidification at night to make the cabin quite comfortable.
If you are seeking only a cold cabin night's sleep, then the stand up units will do the trick, providing that the exhaust hose is insulated and discharges out the boat. If you are seeking to stay below during a hot summers day then FORGET ABOUT IT! These units just cannot keep up with the heat buildup inside. The only way to really cool down the cabin is the costly Marine AC unit. The big question for us has been: are we ready to spend over $3000 (unit, install kit and labor) to enjoy that luxury?
Bob
Lake Lanier, GA
We had a 26' with the type of Ac you are talking about and it barely made a difference (dropped temp by 10 degrees, but not on a super hot day)...worked best as a dehumidifier...if you did not want to spend the $3K go with a companionway window unit...They are a pain in the A$$ to store and haul in and out but work well (dropped temp 20+ degrees on hot days and slightly smaller to store). I just bit the bullet on the $3k marine air, I justified it to add value to the boat. good luck
I have one in my C36. Not withstanding that analysis, it works perfectly up to about 85 degrees. Still acceptable to 90. I can run it on a Honda 2000 if needed. I guess it comes down to how many on board etc and how cold you want it. It isn't as simple as creating a vacuum and displacing cold air. And I do it where it retains the water. It'd be even better if I used a drain, as it is optional. And this with no sealing of duct. I think it's a 10000 Home Depot deal. Cheap and can wedge into the aft berth entrance. On a 30 it'd freeze me out.
I saw a write up somewhere about mounting a cheap window AC unit in the bulkhead between the vee berth and chain locker, where an access door would normally be. Provided there was a good sized vent into the space from on deck and you didn't anchor out a lot, that could work. It wouldn't leave much room for the anchor rode though. I anchor a lot and carry about 600 feet of rode so I don't think it would work too well on my boat.
We have an 11,000 BTU stand up unit like the one described & it is quite powerful (over twice as many BTUS as the typical 5,000 btu window unit). For the cost of around $300. it puts out a lot of cold air. Don't believe Jwing, they work great, & for the money are hard to beat. If he hasn't actually used one then how would he know. We own one & I can testify it works. We don't have the aft berth port, so we compressed the hose & vent it straight out of the bottom of the companionway. You can still get around it during the day, & at night we put in the two upper companionway boards to improve efficiency. If we're just running it briefly during the day we fill in around the companionway with towels. We keep ours mounted to the right of the companionway steps, as there is plenty of extra space there, & a couple of bungy cords keep it from moving around.
We used to have a marine A.C. unit on our last boat that mounted to the forward hatch & was expensive & didn't work worth a damn, other then in the forward berth. It also dripped condensation onto your head at night, yuk.
The window units in the companionway are a complete PITA as stated above. They are bulky, heavy & will invariably drop at some point, either on your foot, or will scratch the crap out of your deck gelcoat. Plus once they're in the companionway, no one else is getting in or out. Not really practical. Try out one of the stand up units for a few hundred bucks, & if ya don't like it, take it back to where ya bought it. No harm to try it. My 2 c.
We used to have a marine A.C. unit on our last boat that mounted to the forward hatch & was expensive & didn't work worth a damn, other then in the forward berth. It also dripped condensation onto your head at night, yuk.
The window units in the companionway are a complete PITA as stated above. They are bulky, heavy & will invariably drop at some point, either on your foot, or will scratch the crap out of your deck gelcoat. Plus once they're in the companionway, no one else is getting in or out. Not really practical. Try out one of the stand up units for a few hundred bucks, & if ya don't like it, take it back to where ya bought it. No harm to try it. My 2 c.
I had one given to me; I do know how they work. Gave it back within three days. I'm an architectural mechanical engineer. My specialty is energy efficiency.
Except for dealing with condensate (yes, some units sling the condensate onto the condenser coil - so do some window units - but they can be overwhelmed then drip), tell me one thing about my post that was inaccurate.
By the way, how many cubic feet of space does your boat's cabin contain? My 22,000 Btuh home unit cools 13,000 cubic feet in Alabama heat and humidity. But you need 11,000 Btuh to cool your boat? See what I mean? You might feel cool, but you are wasting a lot of energy. And you need to jerry-rig an inconvenient configuration to make it work.
I do agree that you can try one though, then take it back to the store if you don't like it. That's what my friend did with the one she gave me.
Except for dealing with condensate (yes, some units sling the condensate onto the condenser coil - so do some window units - but they can be overwhelmed then drip), tell me one thing about my post that was inaccurate.
By the way, how many cubic feet of space does your boat's cabin contain? My 22,000 Btuh home unit cools 13,000 cubic feet in Alabama heat and humidity. But you need 11,000 Btuh to cool your boat? See what I mean? You might feel cool, but you are wasting a lot of energy. And you need to jerry-rig an inconvenient configuration to make it work.
I do agree that you can try one though, then take it back to the store if you don't like it. That's what my friend did with the one she gave me.
I'm not a mechanical architectural engineer. Mine works perfectly for $300. I can remove it easily in the winter. Freezes me out at night and helps in the middle of the day. On a C36 and not the 30. But again... I'm not an architectural electrical engineer.
This may not be the perfect setup but it works well enough and the price was right. I installed a small window unit in the plywood panel that separates the the galley from the port lazarrete locker. A lot of people have microwaves mounted in this location preventing this type of install. It does a decent job dropping the temperature by 10-15 degrees and removing humidity. Obviously the locker has to be left open when the AC is in use for ventilation, but it save us having to move a heavy and cumbersome AC unit around when not in use.
Thanks for the backup guys, even if I'm not a mechanical engineer,
I am a licensed building inspector with a master's degree.
If I'm not paying for the electricity & the marina is, then I say go for it.
For $300 bucks, the cooling capacity can't be beat. Cheers.
I am a licensed building inspector with a master's degree.
If I'm not paying for the electricity & the marina is, then I say go for it.
For $300 bucks, the cooling capacity can't be beat. Cheers.
I placed a $ 100 window unit in the companionway off to one side. Then I bought a piece of half inch plywood and cut a square out of the bottom so it would slide over the a.c. and replace the hatch boards when the a.c. was in use. I put a carry handle on the top of it.There was plenty of room to step around it, it was cheap and easy to stow. This was in an ODay 25. The a.c. had a thermostat and kept an even temp even in the hottest weather.
Jwing, I'm on Guntersville as well. Brown's Creek.
Jwing, I'm on Guntersville as well. Brown's Creek.
It is my intention to install the same type unit in my forward hatch with some foam board ducting on my Catalina 22. The hatch is on the sloping section forward of the hatch slider, so the hatch lid would be open just slightly over horizontal. Should be easy and out of the way.
Let me jump back into the pot here about the free standing AC units. In my earlier posts I did mention that they will cool and dehumidify and that on hot summer nights onboard here in Georgia the Heier unit we had did the job. That was because we insulated the exhaust flex hose. That for us was the secret in keeping the cabin cooler at night. The problem we encountered was that the unit was not powerful enough to keep the cabin cool as the day heated up. Lets face it, Catalina 30's are not well insulated either. We had to be out of the cabin early!
We have considered going for a stand up unit again but with the highest BTU value we can find and I believe that is 11-12K. They are affordable and easy to stow. As for daytime use in summer heat? This is where the marine built in AC units excel, but at a higher cost. We shall see what the higher BTU's do during the day. We want to be comfortable onboard during hot and humid nights while at the marina. For the money, they are worth it :dance:
Bob
1988 Mark II
We have considered going for a stand up unit again but with the highest BTU value we can find and I believe that is 11-12K. They are affordable and easy to stow. As for daytime use in summer heat? This is where the marine built in AC units excel, but at a higher cost. We shall see what the higher BTU's do during the day. We want to be comfortable onboard during hot and humid nights while at the marina. For the money, they are worth it :dance:
Bob
1988 Mark II
I wonder why the free standing units don't have 2 vent hoses one to pull outside air in and another to exhaust it. Then it wouldn't have to pull your cooled air out of the space that is being cooled. That would make it nearly as efficient as a window unit.
Edit... They do have two hose units. That may explain the difference in perception of these units.
Edit... They do have two hose units. That may explain the difference in perception of these units.
This topic comes up all the time. These portable units have been bashed here more than once. I have a single hose portable unit and does fine. It won't freeze me out on a sunny 95 degree day but does lower the humidity and make it comfortable down below. If I were to get another one I would get the 2 hose units. That way it isn't sucking cool room air to re-cool. That cool room air needs replaced so it sucks hot outside air through the nooks and crannies and mixes with the cooled air.....not very efficient. I basically made a 2 hose unit from my one hose though. I enclosed my unit in the hanging locker and cut a hole in the bulkhead for cold air to enter the salon. I have my wrapped exhaust hose exiting a portlight. I rigged up another hose to the portlight for intake air that goes into my sealed hanging locker. It's not perfect but seems to pull most of the air from the outside instead of using the cooled inside air. I paid $300 for mine. It cooled my boat from 98 degree humid air to 82 degree drier air with in a half hour.