AC rust

[Bob 04 H260]

This is my first boat with AC on board, so my questions may be a little basic.

I have the factory installed AC unit under the starboard settee. It sits in a steel tray with 1" sides. All the condensation goes into the tray. When the water gets to be more than about 3/4" deep it drains out through a hose into the keel sump and the bilge pump eventually pumps it overboard. I intend to redirect the drain into the shower sump. Because the tray always has almost an inch of water sitting in it the steel tray under the AC unit has quite a bit of rust and the compressor, condenser etc. are all quite rusty. Is there anything it can be coated with to prolong the life ? Should it be serviced in anyway ?

I don't see any way to drain the water away at a lower level. Is this a "normal" installation ? does it effect the lifespan of the AC unit or are they designed to be used this way ? If so it would make more sense to me if the tray were made of plastic.

thanks Bob

 

[kloudie1]

That is a common problem.. I installed the unit in my boat and noticed that the water wouldn't drain away very well.. After about 16 years, the water corroded a pinhole through the compressor housing .. The pan was corroded severely but not leaking.. I rebuilt the pan and installed a new compressor . I layered the liquid pickup truck bed liner stuff into the pan to keep the water from corroding that .. I sprayed liquid galvanizing compound onto the compressor base.. the most important part is that I shimmed the pan so that the water drain is the lowest part when the boat is resting at the slip.. I would recommend shimming your pan so that it is slightly tipped down toward the drain . This will keep the water from pooling under the compressor so much.. Notice that many of the new AC units do have plastic condensate pans. Middle picture is the compressor showing the leak location.. Note how the water was a little over an inch deep .. I have it shimmed now so the compressor bottom is not in the water.

 

[Don S/V ILLusion]

Moving the drain to the lowest point would be the obvious solution to that problem.
Keep in mind that any ferrous metal will rust in that environment regardless of what you do try to prevent it so why not switch to a SS or plastic drain pan?

 

[DeniseO30]

This is why "marine" ac and refrigeration is not really built for marine duty. On the other hand, if they built units with copper or stainless pans and powder coated the steel components the costs would be astronomical. Everything is trade offs.. the pans could be sprayed with liquid rubber of some sort.. even roof coating would work if it's not in the tropics. but once the rust is started.. it's a cancer.

 

[robertsapp]

Get one of these:

http://www.mmair.com/marine_division/accessories/mermaid_condensator

It solves two problems at once. It sucks the condensation out of the pan, keeping it dryer, and it directs it to the seawater overboard discharge line, keeping it out of your bilge.

 

[Bob 04 H260]

Get one of these:

http://www.mmair.com/marine_division/accessories/mermaid_condensator

It solves two problems at once. It sucks the condensation out of the pan, keeping it dryer, and it directs it to the seawater overboard discharge line, keeping it out of your bilge.

Thanks Robert ! very smart solution, I will get one..........

the other suggestions are good too, I have the boat hauled for the summer so it should be good and dry by fall, I will look into a coating to deal with the rust issue and give it a good coat to try and slow down the deterioration.

Bob

 

[onecoolair]

Got me three of these one for each a/c unit. Screwed right into sea cock at a/c discharge thru hull above water line. Placed suction hose at lowest point in pan. Problem solved.
http://www.aquaticeco.com/subcategories/1546/Turbo-Venturi-Injectors

 

[Rick R]

Rusty AC followup

Hi onecoolair,

Had a follow-up question: I checked on this part you shared and the dealer tells me that it doesn't have any kind of check valve or backup preventer. That worries me a bit if there was some kind of "problem" and water backed up into the drain pan instead of going out the seacock. Did you install a check valve or anything of that sort or did you just go 'as-is'?

Thanks

doggoner

 

[Ken13559]

Hi onecoolair,

Had a follow-up question: I checked on this part you shared and the dealer tells me that it doesn't have any kind of check valve or backup preventer. That worries me a bit if there was some kind of "problem" and water backed up into the drain pan instead of going out the seacock. Did you install a check valve or anything of that sort or did you just go 'as-is'?

Thanks

doggoner

I think its to be installed above waterline. I suppose it need an air pump to get a flow into the venturi?

 

[onecoolair]

Re: Rusty AC followup

Rick thanks for asking. Never had a problem....All 3 a/c Discharge fittings are at least 10 to 12"s above the water line. There is a proper sea-cock on each fitting. Just looped the small suction tube about 12"s or so above sea-cock. Keep in mind the a/c discharge is only under water when boat is heeled over and at that point we are doing at least 5 knots. Have you ever sailed a small day-sailor with a self bailing cockpit. Same principle works here. Also when heeled the main a/c unit is at the higher point. Now the smaller unit is not, it is under the starboard settee and is right next to hull. It was the one I was a little concern about, but so far no issues. Both the discharge fittings are at the max beam of vessel. The 3rd unit is in forward cabin under v-berth to port side it sits a bit higher. I believe the pan is at water line. The discharge for it is right next to unit. I get great suction when units are running and when sailing as the boat is moving along. The only time water could come back up the tube is if I had a knock down. At that point there are bigger problems. I would recommend you handle and take care of how you install this venturi pipe. The plastic is supposed to be pretty strong but it does not hurt to use reasonable care that it is in a safe location along the hull. It would be nice if it was made of better plastic. What is really nice for me is with the male and female threads the piece threads right in to the sea-cock and the other end threads right to the fitting on the hose. Can be remove and put back in,in about 5 minutes. I have had some thought about glassing over the fitting and reinforcing it. But have found it not necessary. Mine have been in use for above 3 to 4 years now and have not shown any signs of cracking. Other then that they work fantastic. Some of my neighbors have go this way. One neighbor set their boat up this way after they had to spend big bucks replacing a portion of there cabin sole because of the a/c.