Air Conditioning Water Pick-up
 

My AC unit pulls water from under the boat to cool the cabin (I think most work like this). In the engine bay, there is a shut-off valve just after the pick-up. Does this need to remain closed while running the boat, and opened only when you are stopped and turning on the AC? Can is cause peoblems if left open all of the time?

Sorry... first boat with AC.

Thanks!

Re: Air Conditioning Water Pick-up
 

no you can leave it open all the time

Re: Air Conditioning Water Pick-up
 

You can leave it open, however it will pump water through the system as you boat and you will have a stream coming our the exit hole at the bow. My only concern was that if you ever sprung a leak anywhere in the system you could pump a lot of water into the boat before you knew it.

I always turn my valve to the closed position while boating.

Re: Air Conditioning Water Pick-up
 

Is there any reason not to put a air or gen water pickup off of the transom where it will not be in the water at speed? There would never be a reason to run either at speed would there?

Re: Air Conditioning Water Pick-up
 

welcome to the word of fountain ect

thats the best way to do it, but usually requires pulling a mtr

Re: Air Conditioning Water Pick-up
 

Anybody out there have pictures of pickups not in the water but using a transom mounted pickup? The BT has two pickups out the bottom but I always thought anything disturbing the water flow in front of the drives was wrong.

Re: Air Conditioning Water Pick-up
 

I put mine here, But I had to pull the engine

Re: Air Conditioning Water Pick-up
 

I just move mine without pulling the engine. Mine was on the bottom, and is on the transom now. used the a/c yesterday and it works great. Ill go get a pic of it.

Re: Air Conditioning Water Pick-up
 

What did you use to plug the old hole? Or, did you reglass and gelcoat ?

Re: Air Conditioning Water Pick-up
 

My next question also. I was thinking of having a stainless plate made that fit in the same location and bolt pattern.

Re: Air Conditioning Water Pick-up
 

I took mine to a fiberglass guy who really knew what he was doing. he said he slightly opened the whole up, repatched it with balsa wood, and re fiberglassed it and gelcoated it. you cannot tell on the bottom. you can tell in the engine compartment, and the only reason is the area he patched is whiter. cost was about $350.

Re: Air Conditioning Water Pick-up
 

Baja Runner, Don't forget the pic.

Re: Air Conditioning Water Pick-up
 

I forgot to take one before i took it over to storage. Ill get one the next time i run over there.

I copied the same spot dock holiday did on his 36. theres a pic of his here on oso somewhere.

Re: Air Conditioning Water Pick-up
 

We pulled ours off the bottom this winter and put it in the transom.

Works great.

Re: Air Conditioning Water Pick-up
 

My A/C unit wont pull water from the lake, the valve is open and I dont think I have vapor lock......... Any ideas? There is a red deal just above the water filter that looks like a water pump/impeller, could that be bad?

Re: Air Conditioning Water Pick-up
 

sunday was the first time i used mine. it wouldnt do anything at first. i kept switching the water pump and a/c on and off, and it finally started working :confused: (the water pump)

I do know there is an impeller in there that can go bad though.

Re: Air Conditioning Water Pick-up
 

You have to get them primed, at least I did on mine.

If it was the first time out for the season I would open the valve and run the boat just a little to force water in the system.

When you go to pull the boat out of the water close the valve first and you will not have to prime it the next trip out.

Re: Air Conditioning Water Pick-up
 

OK, since i get about 4 of these types of calls per week let me shed some light about them. :)
Putting the pickup on the transom is no problem.....BUT....that's only as long as your pump and the pickup line is mounted below the water level. I'd say about 80% of the pumps on the market for marine AC systems are ours...(March Pumps) and our pumps are not self priming. So if you have a service loop in the system and have an air pocket in the line or inside the pump it wont work. One problem i see with the transom mounted pickup is when you get underway the line will bleed out the water and then you have air in the lines.....so again if your pump is mounted above the water level it will never prime itself again till you get the air out. Many boaters that cant mount the pumps below the water level put a "T" on the output side of the pump with a garden hose attachment so they can prime the system if it looses prime.
Another common call i get is in the beginning of summer when people put the boats on the water for the first time....they go to start the AC system and nothing works.....people winterize the engines just fine but forget about the AC system and what happens is the water pump usually gets the brunt of the freeze and cracks....time for a new one :(
Another common problem is seaweed gets sucked into the pump......get a small sea-strainer or filter to trap this stuff before it gets into the pump...
I'm sure i'll think of a few more after i post this but its what comes to mind right now. If you need any help feel free to call and ask for Walter
March Pumps-847-729-5300

Re: Air Conditioning Water Pick-up
 

Since i mounted mine on the back of the boat, what about putting in a check valve to keep it primed?

is it bad turning on the pump unprimed?

Re: Air Conditioning Water Pick-up
 

Check vales are fine....as long as they are not smaller in size I.D wise to cause a restriction......and we recommend on all our centrifugal pumps to mount any valves on the output side of the pump to lessen the chance of causing a restriction. As for turning the pump on unprimed.....depends on what pump you have......out smaller pumps like the 2C and 3C models can run for up to an hour without damage....the bigger pumps like our series7, 8, and 10 (Which don't get used in boating applications) can only run for a few minutes before damage occurs. The most common damage we see from extended dry running is melting the back side of the impeller....whats happening is with no water in the pump the impeller is being pulled against the rear pump housing by the magnets....then its plastic on plastic contact with no cooling and sooner or later the plastic will overheat and start to melt......

Re: Air Conditioning Water Pick-up
 

Good info. Thanks Should I assume the same holds true for the generator? It is definitely above the water line. Not sure what type of pump it has, but will be in there headfirst tomorrow!!

Re: Air Conditioning Water Pick-up
 

The genset has a rubber impellor and it will not tolerate runnng dry. I'd put a "T" in the pickup line with a hose connection to make sure it's primed --it will also let you test and run the genset on the trailer or work rack.

The manual says gensets should be run for and hour per week with full load to minimize carbonn problems, dry gaskets etc in fuel system.

If you dry sotre or trailer boat you are going to have "air-lock" problems with AC and genset so you may as well just get setup to prime both.

Re: Air Conditioning Water Pick-up
 

The genset pump is different and will pull it's own prime. There will be a short run dry but most times it is no big deal as long as a little water is still in the pump (like starting your engines after being on the trailer). If it has sat for a long time and the pump is dry, a little prime water would be good to lube the pump. I know the pump on my big boat genset is rated for a 6 foot pull, and that sucker pumps some serious water.