Air Conditioner BTU recommendations, please

R

Rotzy

New Member
Sep 14, 2020
22
RI
Boat Info
260 Sundancer, 2002
Engines
MerCruiser 5.0MPI, Bravo III
Hello everyone.

I'm looking to install AC on my '02 260DA this winter and was wondering what size unit I should go with. The optional factory unit was 7000 BTUs, but most units these days are either 6000 or 9000 and I'm torn about what size to go with.

I boat in the Northeast but despise heat and humidity when trying to sleep. My goals are the following:

- #1: It has to be effective at cooling the boat in a reasonable time frame
- I'd like to add as little weight to the boat as possible
- I want it to take up as little room as possible (I will be installing it in the starboard wall of the mid cabin)
- I want to be able to run it off my 2kW generator (please don't start a conversation about portable generator use).
- I don't want to worry about it freezing up or cycling on/off frequently because it's too big for the boat.

Suggestions?
 
Talk to the manufacturer of the unit. They can help size it. But my gut says go a bit smaller so you don't have it cycling on/off too much.
 
Golfman25 said:
Talk to the manufacturer of the unit. They can help size it. But my gut says go a bit smaller so you don't have it cycling on/off too much.
Click to expand...

I tried. They were absolutely NO help. After determining that this was not a replacement unit but a clean install, they wanted dimensions of the cabin, furnishings, appliances, etc. to even give a guess at a unit size. I asked if they could simply tell me what size most people were purchasing for the same boat, they said no and suggested I have a marine HVAC specialist come out and give a recommendation. I was speechless at their utter lack of assistance.
 
Rotzy said:
I tried. They were absolutely NO help. After determining that this was not a replacement unit but a clean install, they wanted dimensions of the cabin, furnishings, appliances, etc. to even give a guess at a unit size. I asked if they could simply tell me what size most people were purchasing for the same boat, they said no and suggested I have a marine HVAC specialist come out and give a recommendation. I was speechless at their utter lack of assistance.
Click to expand...
I can see where they are coming from ...imagine all the variables. Searay already told you the size...keep in mind how you are going to vent it....if you can’t easily distribute the cold air Fore and aft you will be cold up front and warm in the back..... and a bigger unit won’t help that
 
Blueone said:
I can see where they are coming from ...imagine all the variables. Searay already told you the size...keep in mind how you are going to vent it....if you can’t easily distribute the cold air Fore and aft you will be cold up front and warm in the back..... and a bigger unit won’t help that
Click to expand...

Ideally, I would install a 7k unit, but they are not as readily available as the 6k and 9k units.

They were truly less than helpful. I suspect a marine AC manufacturer has some idea of what size unit works best for many of the popular boats on the market. I'm not trying to cool a house or a larger cruiser with challenging dimensions!

True, distribution is important, and I intend to install the ducts/return in the factory locations. However, since a supply and the return are both located in the very cramped mid cabin, I do expect that area to be colder. Not much I can do about it without sacrificing the very limited space in the v berth for the AC unit, which I'm not willing to do.
 
I installed a 5000 BTU unit in my 260DA. It was plenty of cooling on the great lakes even on the 90'F+ days. If I were in FL I would have gone to a larger unit. If you go to large it will not remove the humidity from the cabin.
 
Rotzy said:
Hello everyone.

I'm looking to install AC on my '02 260DA this winter and was wondering what size unit I should go with. The optional factory unit was 7000 BTUs, but most units these days are either 6000 or 9000 and I'm torn about what size to go with.

I boat in the Northeast but despise heat and humidity when trying to sleep. My goals are the following:

- #1: It has to be effective at cooling the boat in a reasonable time frame
- I'd like to add as little weight to the boat as possible
- I want it to take up as little room as possible (I will be installing it in the starboard wall of the mid cabin)
- I want to be able to run it off my 2kW generator (please don't start a conversation about portable generator use).
- I don't want to worry about it freezing up or cycling on/off frequently because it's too big for the boat.

Suggestions?
Click to expand...
If the Factory spect out 7000Btu i would try to stay as close to that number as possible and not to exceed the 7000. You may want to lean towards the 6000 BTU unit so you don't quick Cool down the boat. BY undersizing the unit a little bit will not only give you cooling, but will pull down the Humidity which is the key! As far as the size and weight of the units will be minimal.
 
The calculator pushes you to the smaller one. That's what I used to have on my boat years ago.
 
I have a Sea Ray Sundancer 330. My CruiseAir 12K BTU unit died two years ago. I replaced it with a MarinAire 9K unit from that company in Miami. This was the second year. I live in Southern Ontario, and this summer we had a period with 90 plus temps every day and high humidity. My cabin stayed nice and cool. I am very happy so far with the MarineAire unit and works as well for me as the 12K it replaced. They make a 6K unit. https://www.marinaire.com/Marine-air-conditioner-6000-btu-110V-p/msba6k2.htm

Mermaid has a 6,500K unit.
https://www.mmair.com/marine-division/marine-air-conditioning/6500-btu-system/
 
If you do not have a generator you can only use it on shore power. If you have a generator it will use 1 GPH. Our master cabin is 13.5 by 10 feet the AC is 7,000 BTU. At 90f out side it takes 2 hours to cool the room to 70F. It draws 10 AMPs at 120 volts. WE have never run AC on the generator. We run the heating part of the AC at anchor on the generator as that is the only heating system the boat has.
We have 3 AC units on the boat they are original to the boat. Size is about 1.5 feet long, 1 foot high and 1.2 feet wide.
 
douglee25 said:
Also check out Mabru AC... They make a 7k and are based out of FL.

https://www.ebay.com/itm/Marine-Air...-boat-Air-Conditioner-Mabru-SC7-/233023104286
Click to expand...

Thanks. Their price seems quite a bit higher than I was hoping to have to spend on the unit.


Creekwood said:
I have a Sea Ray Sundancer 330. My CruiseAir 12K BTU unit died two years ago. I replaced it with a MarinAire 9K unit from that company in Miami. This was the second year. I live in Southern Ontario, and this summer we had a period with 90 plus temps every day and high humidity. My cabin stayed nice and cool. I am very happy so far with the MarineAire unit and works as well for me as the 12K it replaced. They make a 6K unit. https://www.marinaire.com/Marine-air-conditioner-6000-btu-110V-p/msba6k2.htm

Mermaid has a 6,500K unit.
https://www.mmair.com/marine-division/marine-air-conditioning/6500-btu-system/
Click to expand...

MarineAire was the company I was considering purchasing from. They seem to have a compact product, favorable reviews and nice features at a low price point.

I contacted Mermaid to ask about their product and pricing. I'm waiting to hear back from them. Their website does contain a lot of information about their products and some general info on what size boat each unit is acceptable for. The 6500k unit seems to be a touch larger than the 6k MarineAire unit, I'm not fond of their controller but I'm sure I could live with it, and I don't see an option for a remote.
 
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douglee25 said:
I think the majority if I'm not mistaken. Dometic units are not copper coils.
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I am pretty sure the coils on my Cruisair and the Marinaire are copper. The fins on the units are aluminum, but the coils themselves are copper. If they are aluminum, better not use acid to clear barnacles and debris.
 
All the Dometic / Cruiseair products use copper or cupronickel coils and heat exchanger. I've never heard of a marine AC system using aluminum tubing.... @douglee25 - where do you source that info?
 
I have the slightly larger 07 260da with factory 7k btu and we boat in N.J.

my observation is that the unit doesn’t keep up on the 90++ days when the sun is out. Set at 70 and it runs 73-75 in the late afternoon in our mid 80s bay. usually hits set point within an hour Of sunset.

definitely working properly, had a cruiseaire dealer service it. Heat is excellent even with water in the middle 40s. Really does great with humidity control by not short cycling. Even when the temp is higher because it can’t keep up it’s comfortable from the dehumidification.

in Rhode Island I might favor the 6k,particularly if the water was cooler. Should be more efficient in cooler water
 
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