AC pump prime confusion

[Bob a Buoy]

My 300DA is dry stacked, my Ac pump appears to be below the waterline. If my seacock is open when the boat is splashed shouldn't water enter the pump and self prime?

 

[Bob a Buoy]

Yeah, that has been my experience and goes along with what I've read. I just don't understand the physics. I'm going to start closing the valve before lifting. I need to learn the method of breaking the pump outlet connection and allowing water to flow and/or running water into the outlet for times when I forget and can't get out on the water to run the boat.

 

[Bob a Buoy]

Definitely.

 

[Ray Ray]

Or, you could buy a Sea Flush system, which you can use for this and other useful DIY projects: http://www.seaflush.com/

In the event you lose prime after being stacked, and don't feel like taking a run to re-prime the pump, just launch/splash the boat and take a hose connected to shore water in the bilge with you. Use the Sea Flush and you're AC strainer to push water thru both the thru-hull and the rest of the system and you're back in business.....works like a charm.

I used the Sea Flush system for this and winterizing all systems....couldn't be easier, and much cheaper than paying the shop to do it.

 

[Xplicitlnck]

Or you can go the free route and put the hose on your seawater outlet. Backlash and enjoy your cold cabin

 

[Bob a Buoy]

Or, you could buy a Sea Flush system, which you can use for this and other useful DIY projects: http://www.seaflush.com/

In the event you lose prime after being stacked, and don't feel like taking a run to re-prime the pump, just launch/splash the boat and take a hose connected to shore water in the bilge with you. Use the Sea Flush and you're AC strainer to push water thru both the thru-hull and the rest of the system and you're back in business.....works like a charm.

I used the Sea Flush system for this and winterizing all systems....couldn't be easier, and much cheaper than paying the shop to do it.

Cool, thanks for the link!

 

[Bob a Buoy]

Or you can go the free route and put the hose on your seawater outlet. Backlash and enjoy your cold cabin

Agree, that is one of the two options I mentioned above that I need to try and master for times when I need it. My only concern there is getting to it at the dock and holding a hose against it.

 

[ASH]

We have trailered or lifted boats with air conditioners every outing for 15 years, I have had it happen two times that we had to garden hose the outlet. You may not have a problem at all.

 

[Bob a Buoy]

Ok I have another question, I'll have the boat on a rack tomorrow for some cleaning, if I close the valve and run water into the thru hull outlet, filling the system, and leave it closed until the boat goes back in the water, will that take care if it?

 

[Molson]

It may not be able to push the air out.

 

[Bob a Buoy]

Good point. Guess I'd somehow have to leave the valve open then close it after the water ran for a bit.

 

[ImpulseIII]

Nope. Whether it should or not, it usually doesn't. Take it for a ride and it will prime itself.

What you could do, although it would be a pain in the butt, is close the seacock valve before it is lifted from the water, and then re-open it when it is splashed. That should trap the water in the system, and would prevent it from getting air locked.

And what about the water freezing in the A/C line? Really not such a good idea.

 

[Ray Ray]

Good point. Guess I'd somehow have to leave the valve open then close it after the water ran for a bit.

It would be a two person job, unless you could somehow secure the running hose to your AC/seawater outlet on the side of the boat, and then close the seacock while it's running.

Otherwise, one person to secure the running hose flushing water back through the whole system with the seacock open (it should drain thru the thru hull while running), while someone else is in the bilge to close the seacock while the system is being back flushed.

 

[JVM225]

Or you can go the free route and put the hose on your seawater outlet. Backlash and enjoy your cold cabin

That's what I do.

 

[JVM225]

Easiest way to prime the AC is to go for a ride. That doesn't always work. When it doesn't, just take the hose off of the discharge side of the pump (with the pump off and seacock open) for a seond until water comes out. Shove hose back on barb, tighten clamps, turn on AC, and enjoy it.

 

[Bob a Buoy]

So just hold it there til the air is forced out the inlet on the bottom of the hull? Do you have to hold it tight against the hull with your hand or could I just squirt a hard pressure stream aimed at the outlet hole?

 

[peterkvs]

On my previous boat I fixed this problem for good. Here's how.

On the output side of the pump I installed a tee in line with the tee facing up. To that tee I installed a normally open 120 volt solenoid valve. On the output side of the solenoid I put a 1/8" hose barb and a hose that went above the waterline. I actually vented that hose overboard, just in case the solenoid valve died. I tied the solenoid valve into the pump power.

So, when the A/C is off the solenoid is open and the water comes into the pump through the seacocks and primes it because the air can escape through the solenoid. When the pump turns on, then the solenoid valve energizes and closes and the water pumps through the a/c as intended.

Pete

 

[Bob a Buoy]

Gotcha sfergusen, and no we are not talking about winter operation, at that point I will allow all water to drain out of the system.

 

[Bucit]

Kevin27 installed a "T" on the hose after the pump and put a ball valve on it. When he splashed the boat he turned on the A/C and opened the ball valve to release the air. Once water started trickling out (into the bilge) he closed the vale and A/C was running.

 

[JVM225]

Not sure which you were looking for clarification on, so here it is for both things.
1. I back wash my AC system with the boat out of the water. All that's involved is taking the nozzle of my garden hose, holding it up tight against the discharge, and then pushing water through the system backwards until it comes out of the intake. Once finished, I remove the strainer, clean it out, and re-install it.
BTW: I use the same idea to winterize the AC. I use a hand pump attached to a container and push the pink Anti Freeze through the system until it comes out of the intake. Then I'm finished.
2. I prime my AC by taking the hose off of the discharge side of the pump (the pump is turned off) for a split second until water comes out of the pump (pushes the air out on it's own), then I put the hose back on, tighten the clamps, and enjoy the AC. You don't get a high pressure flow of water, so there I minimal water coming in to your bilge for the second the hose is off.

My AC pump is very easy to get to, so I keep it pretty simple. Installing a tee valve with, or without, some sort of solenoid to release air might make sense if your AC pump is in a tough place to get to. It will do the same thing. Since mine is easy to get to, I do it this way to minimize the amount of fittings and clamps. I've always felt that the less connections you have, the less potential points of failure you have.
The idea is to open the discharge side of the pump briefly to allow the water to push the air out of it. However you accomplish it, it doesn't matter.
Sometimes, depending on the boat, you can just take it for a ride and the force of the water pushing up through the intake will push the air out of the pump, then through the intake hose, the AC unit, and out the discharge, but it doesn't always work on all boats. Probably because of the hull design and location of pickup and/or pump inside the boat.