"Burping" the AC ... ???

charlieft

charlieft

Member
Nov 14, 2006
166
Plymouth, MA
Boat Info
2003 300 Sundancer,
Engines
T-350 Magnum w/Bravo III
Hi All,

Our AC unit is not pumping water. The seacock is open and the pump sounds like it's running OK. I was told that the system is probably "air bound". Is there an easy way to correct this? ... I have scheduled drive maintenance and they're going to look at the AC also, but I would prefer to fix it myself if possible and save the extra $250 or so on my bill. I'm going to look at the sea strainer ... any other suggestions? We just got the boat so I'm not really familiar with all the systems yet. The boat sat for a year or more, so there are a few issues from lack of use.

Thanks,
 
Close the raw water seacock. Remove the output hose from the a/c pump. Open the seacock until water flows out of the output hose. Close the seacock and reconnect the hose. You should be good to go when you turn the a/c on.
If your boat has a genny, you should be able to prime the a/c pump just by operating the a/c while running the boat on plane.
 
Charlie,

Has the boat been in the water yet? (not a silly question readers he's only about 30 miles south of me and only a few boats are in). If you are still on stands the AC won't run short of connecting a hose to the hull pick up.

If you have just splashed and pump won't prime, its because the AC water pumps can not self prime. The easiest way to get them to prime is to take the boat for a run with the seacock open.

I know you can put a water hose against the AC exit through hull and run water backwards through the system (Its how I antifreeze mine). I don't know if it would work to prime the pump, but you could try it.

Henry
 
Thanks for all the info ... Yes, the boat is in ... I'm heading down there now to try a few of your techniques.
 
I got it working ...
I cleaned the sea strainer, took off the hose going from strainer to pump and stuck a water hose against the strainer outlet while the pump was running.
Running a hose into the exit through-hull didn't work.
Was going to Try running water back into the pump from the exit side, but couldn't get the exit hose off the pump ... I was afraid that I'd break the plastic elbow off the pump if I pulled any harder.
 
charlieft said:
I got it working ...
I cleaned the sea strainer, took off the hose going from strainer to pump and stuck a water hose against the strainer outlet while the pump was running.
Running a hose into the exit through-hull didn't work.
Was going to Try running water back into the pump from the exit side, but couldn't get the exit hose off the pump ... I was afraid that I'd break the plastic elbow off the pump if I pulled any harder.
Click to expand...
I'm curious, did you try the hose in the thru hull with the pump running or off?
 
Woody said:
I'm curious, did you try the hose in the thru hull with the pump running or off?
Click to expand...

Good point ... I tried it with the pump off ... I was alone and I had to hang over the bow rail while holding the hose with a boat hook ... didn't want to leave the pump running dry for the amount of time it would take me to climb out there and get the hose lined up. I needed another person to turn on the AC when I had the hose ready.
 
Charlie.
Like SBW stated , simply removing the hose off the discharge side of the pump will work. ( pump should be off) once water starts to dribble out of the pump resecure the hose and ur good to go.... This is the best safest way to do it.

Rob
 
I've found the easiest way to prime as well as winterize is to put a good shopvac hose on the outlet and suck water (or pink) up and through. I've primed and winterized using this technique the last two years. simple and quick assuming you have a decent powered shopvac and AC nearby.
 
I had the boat out twice ... had it up on plane both times, and it did not correct the problem. I don't think there's a "one size fits all" solution to this.

repeat ... I couldn't get the discharge hose off the pump without risking breaking the plastic elbow.
 
I did have to clean out the sea strainer ... maybe if I ran it again after the cleaning it would have done the trick.
 
Getting an air lock in the A/C water line has been a constant problem with my boat. My last 290, same hull as my current 290, did not air lock, but my current 290 does. So as mentioned, each boat seems to have its own identity with this problem.

For me it's particularly aggravating since I dry stack, and each time the boat goes out of the water, and up on the forks, it gets tipped back, and the prime in the water line gets drained out. Then when the boat goes back in, the A/C won't work until I either leave the marina and get the boat up to speed with the A/C running, or I climb down in the engine room, and pull the hose off the pump outlet with the A/C running.

One too many trips to the engine room convinced me to fix the problem once and for all. I doubt many of you will be quite so crazy, but if so, here was my solution:

On the outlet side of the pump, I installed a Delrin 12 volt normally closed solenoid valve (from McMaster Carr, about 40 bucks) onto a T. The water can either flow straight through the T, or if the valve is open, can also flow through the valve, and then through a short length of hose that runs to the bilge.

To prime the system, I turn on the bilge blower for a few minutes (I don't think a sealed solenoid coil can spark, but better safe than sorry), then turn on the A/C, which gets the pump running, and then, sitting comfortably in the cockpit (without the engine hatch open) I hit the momentary switch I wired to the solenoid, which now gives the water a low resistance path to flow through the pump and into the bilge, thus priming the pump. It takes about 10 seconds of holding the switch to prime the pump. The key to getting the pump to self prime with this method is to keep the outlet hose below the water line. If you worry about getting a few cups of water into your bilge, you won't want to use this method, or you'll need a second pump to get the water above the water line and overboard. But like I said, I doubt anyone else will be this crazy.

By the way, before I went crazy, I also tried a check valve to prevent the water from running backwards and out when the boat went up on the forks, but the added flow restriction of the check valve was too much for the A/C, and to add insult to injury, the check valve would leak very very slowly, and after a week or two of the boat being on the tilted stand in drystack, the A/C water line would drain, loosing prime.
 
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Ferg,
What ever rocks ur boat. PROPER and what works for u are two compete different things. One would think for commisioning you would want to be in the bilge making sure the strainers are clear, seacocks open and nothing left in disarray or leaking . To each there own.

Rob
 
Okay, How about this hat trick.

Bring sexily dressed assistant to boat

#1 close sea cock to AC
#2 Open sea strainer and swing lid aside
# 3 bring dock hose to the sea strainer
# 4 Have Assistant open water valve* to dock hose
# 5 place hose into strainer basket
#6 using either hand place hose in the crook of thumb and index finger and use hand to seal strainer lip and hose.
#7 Have assistant go to gunnel and tell you when water is exiting AC through hull. Let run two minutes.
#8 remove hose and turn off water.
#9 close strainer lid and dog down
#10 turn on AC and go get cool.

* Skipper could use a hose end valve, but that would deny dock mates the pleasure of ogling the assistant performing the turn on the hose bibb manuver ( but they'd still be treated to the lean way over to check the water stream manuver)!
 
Is the genset self priming? I keep my boat on a lift and I close the seacock to the genset and AC everytime.

So if this is the case I could leave both open and while underway the water will be forced up the AC seacock and it will prime itself. The genset is self priming and will have no issues. Is that correct?
 
Ferg,
We can disagree. I wasnt trying to be an ass. When people ask for help I think its best to try and show them the right way / safest . UR way if it doesnt prime the units going to go off on a safty device. also what if the units not calling for calling or a/c.... Safe at the dock is all i was trying to convey. So well just let it go. When u have people of all different skill levels u have to try and keep simple and to the point.

Rob
 
B-Fitting said:
So if this is the case I could leave both open and while underway the water will be forced up the AC seacock and it will prime itself. The genset is self priming and will have no issues. Is that correct?
Click to expand...

I think that's correct. I've never had to prime my generator, and I've never known anyone who did. The AC will prime itself, at least on my boat, only if the boat is moving above some minimum speed (I just get up on plane) and the AC is turned on.
 
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We don't prime our genny. Frankly, I've never considered the issue. I just turn the fuel pump on and hit start. Strikes me as a very poor design if this is required on any boat.
 
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