Marine Air Conditioner

[Andrew Dobson]

Good morning fellow sailors

I am looking at fitting marine A/C on my 35 in the next couple of months but I was NOT looking forward to drilling more hull holes (sea water inlet/outlet)

Is it possible to use the engine inlet and divide with T piece ? and use sink outlet etc.

Ideas ?

 

[Don S/V ILLusion]

It is possible, however, not a good idea. You need to see/know if A/C discharge water is flowing and you can’t if it’s below the WL as is the case typically for a sink drain. Also, among the reasons to not share an intake are the competing demand, sucking water out of the competing system in the event of a clog and creating a vacuum on the A/C side which can suck air into the A/C intake breaking the prime.

 

[Justin_NSA]

I would be concerned about sufficient flow getting to the AC and engine when running them at the same time.

 

[Justin_NSA]

Just make the holes and optimize the length of hose

 

[Terry Cox]

Hi Andrew, all good advice by posters to your thread. Our 1991 boat came with dual MarineAir reverse cycle heat pumps. Both systems draw sea water through a Little Giant pump from the same through hull below the waterline, through a sea water strainer and discharge out separate through hulls above the waterline. Very important to observe water flow through the system as others have mentioned. If water flow is interrupted for any period of time it can destroy/damage system components.

 

[Ralph Johnstone]

This will ensure a continuous water flow to the condenser:





Connect it to an audible alarm or go the whole nine yards and use an interlocking relay for a shut down of the A/C.

I know what you mean about another hole in the hull. I wouldn't do it unless I could PROVE it wouldn't work. So get out there and PROVE IT WILL WORK. Install the unit (which you're going to do anyway) and insert a couple of vacuum gauges on your existing raw water lines. If you get much of a negative pressure, increase the size of the lines to see if that will reduce the vacuum. Run two strainers in parallel. If all else fails, blast another hole in the hull and you've lost nothing.

How much work are you willing to do inside to avoid another hole ? ? ? ?

 

[Don S/V ILLusion]

How much work are you willing to do inside to avoid another hole ? ? ? ?

Interesting frame of reference question with no one right answer. We have 9 below the WL and a few above. Last boat wasn't much less. What's one more???

 

[heritage]

I installed an ac unit in my H27 last year and was faced with the same dilemma you are having. I was already considering replacing the head with a composting toilet, so I used the head's thru hull for the ac intake. I then drilled a hole for the discharge about 18" above the water line and near the ac unit. As a side note, I have so far had good luck using a venturi effect device in the discharge hose to keep the condensation out of the bilge.

 

[Ralph Johnstone]

We have 9 below the WL

Ouch ! That's one whole lot of holes. In a much bigger boat with more than one head (I would imagine).

Given the similarities between the H-310 and the H-35, I would assume he has five below the WL thru hulls.

1. Engine cooling.
2. Galley sink drain.
3. Head sink drain.
4. Head toilet suction.
5. Macerator discharge.

You never need another hole in your hull .

 

[Ken13559]

I tee-off my AC cooling water from the Head water intake. I can still use the head flushing while AC is running. Has been for couple of years now.

Ken Y

 

[senang]

Unless you have a generator you will only run the AC when docked. Being docked the engine is not running so no problem for a shared thru hull. If you can not check that the pump is running the AC will overheat and shutdown. Look for the cause and restart AC after cooling down.

 

[Andrew Dobson]

Thanks for all the ideas, its thinking "outside the box" that makes sailing such an interesting past time !