Author Topic: Air Conditioning & Heater BTU Requirements - Actual Exeriences?  (Read 260 times)

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    • Quintessa
Re: Air Conditioning & Heater BTU Requirements - Actual Exeriences?
« Reply #3 on: August 25, 2020, 11:25:53 AM »
My experience on our H49 is the 26k BTU we have is plenty for cooling, and heating as well. Our units are Cruisair and they were installed at Queenlong. There are three units. There is a 7K in the aft stateroom, a 7k unit in the V-cabin which serves the crew cabin as well, and a 12k unit in the main salon. We have been live aboard since 2013 mainly in the Med. and even in the extreme heat of the southern Med we have never longed for more capacity. The previous post mentioned only two units per sea water pump but ours has all three units on one pump (with a Cruisair relay control box) and it works perfectly.

I have only one criticism with the Hylas installation and that involves the ducting in the aft cabin. The output blows directly onto the person on the starboard side of the bunk making this person uncomfortable, hot or cold, when the compressor is running in either mode. We have solved the situation with a very technical fix: short stack of reading books on the night table to block the direct blast of air! A better solution would involve more thoughtful placement of the venting and a little more modification to the standard cabinetry when it was installed.  My only other suggestion would be to downsize the main salon unit to 10k BTU (which I believe would still be sufficient) so that it could likely start with the inverter (Mastervolt 2500 Combi). Since we are in the Med we power most of the boat 110v systems with the inverter.  We can only run one heat pump at a time, which is fine for a couple who just uses the heating and cooling in the master cabin at night, but there are times it would be nice to run it in the main salon also.  we also use the inverter to power the heat pump while motoring which is very nice. 

Bob Knapp,
s/v Quintessa (H49 #46)


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    • Adventures of SeaGlub and the Hesitant Half
Re: Air Conditioning & Heater BTU Requirements - Actual Exeriences?
« Reply #2 on: August 02, 2020, 07:09:51 AM »

Here's my 2 cents: The dometic AC and Heat units work great.  Fortunately for me the ducting was already in place. To me that would be THEE most difficult part if it wasn't already ducted. The actual vents would've required some woodwork and the ducts themselves are about 6-8" wide on the outside after accounting for the insulation (4-6" inside diameter) so that's a lot of space to find under floors, behind cabinets and through bulkheads. For the pump(s) you're gonna need access to a thru hull or two (think the recommendation is no more than 2 units per pump) and they have to be continuous downhill run from the thru hull to the pump, then continuous uphill from the pump to the AC unit. You will also need access to 110v electrical. For me I just used the washing machine breaker already installed on SeaGlub, cut those wires (bc I never plan on having a washing machine) and ran longer wires to my air conditioning brain. 53k BTU sounds like a ridiculously high amount. If you had one 16k unit for each area of the boat (forward, main salon, and aft) that would be way more than enough. I have one 16k and that thing blows cold air like crazy and cools the main salon, galley and aft stateroom in about 3 minutes after turning it on. For efficiency, I close off the forward stateroom. But even when I've had guests and opened the entire boat, the one 16k unit is still more than enough (I just have to redirect some of the air flow with a small DC powered fan). Lance and Pam on Shamaya (49') recently replaced AC units. May ask them directly on FB (search Shamaya). My unit sits under the bench around the table in main salon which is only 24" run to the already built in vent. And there was already a vent screen for air access in that area where the unit is installed. Call me if you want to discuss in more detail.
SeaGlub H46 #22


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Air Conditioning & Heater BTU Requirements - Actual Exeriences?
« Reply #1 on: July 30, 2020, 06:33:06 PM »
I definitely will be adding a new heater and/or a reverse cycle system for heat and A/C.  I would like to know what you are using and if it is working for the environment you are in. The calculations say ~53k BTU's for my 51.  I know this most likely double what I would need, hence querying the group. Anyone in the tropics have details to provide along with boat type?  Cheers, Shaun


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