Carver Owners Forum

Greetings. I am looking to confirm what seems to be the common way of priming the AC water pump.

If we put a water hose in the discharge, do we just put enough water in to fill the discharge and then turn the on the AC?

Also, can anyone confirm the AC discharge is the far left discharge with the stain in this photo?[image][/image]

First time boat owners feeling like a fish out of water.

2002 Carver 356 aft

I prime mine by loosening the top of the strainer and letting the air out.

That didn't work for us.

Normally they need no priming as they are located below the water line so they just naturally fill up when the boat is in the water. Are you sure the seacock is open? If you remove the filter top and no water comes in then the seacock is most likely closed.

Yes I’m sure it’s open water comes into the filter and fills up but never goes out the other side. I am thinking now that perhaps there is some kind of blockage.

Close the seacock......remove the hose from the seacock...lift it up , put a funnel in and get a hose ( or bucket of water) ready to put water in the funnel...fill to the top and turn the AC on, continue to fill until water exits the hull.....you will know when the suction pulls the water thru from the full funnel..shut it down and put the hose back on the sea cock quickly, then open....a little messy but nothing a towel can't fix.

There are other ways but this always worked for us in the spring or after the boat got hauled.

Thank you! This is our first boat and it is a little intimidating.

kclife wrote:Source of the post Thank you! This is our first boat and it is a little intimidating.

Don't be, the systems are really quite basic, just take your time and think it thru.... it may take a couple of tries till you get it right but so long as the rest is ok it will work.....good luck with your new boat.

Welcome aboard, since this is your first experience than lets start from the beginning.

Just a guess but the fitting with the stains around it is probably the AC water exit.

In order for the pump to function, there needs to be a demand for heat or cool from the thermostat. Once this is received, power is sent to the pump. Have you heard the pump kick on? If so and no water is exiting from the thru hull then there is a problem, most likely a pump issue or possible loss of prime.

That being said, these pumps do not require priming as they are set up with filter and pump below the water line which means they just get flooded with water when the seacock is open and the boat is in the water. For anyone who needs to prime, I highly suggest you look at the hose leading from the filter housing to the pump. Does it exit in an upward fashion before attaching to the pump that could cause the line to be above the water line even for a few inches? If so, then a slight correction of this hose should alleviate priming for good. Could also be a screw up when mounting the filter housing. Does the water level in the housing get high enough to exit the housing? Water should overflow from the housing if the cap is removed. If one or the other is not happening then the filter housing is mounted too high, drop it down as required to correct the issue.

Unfortunately the reality is that a few variables come together and conspire to make things difficult now and then. I come across this problem all the time at Spring commissioning. I get away with not having to prime the HVAC systems on some boats but priming is a lot more common than you think. I think a little air lock in the system is all it takes to prevent the pump from doing what it's supposed to do. While it's true the pumps are mounted below the water line, the end result isn't always as expected.

You will have a breaker at the electrical panel for each AC unit on board, and a separate breaker for the AC water pump. I believe your pump is in front of the port engine, if it is, remove the small front section of the port engine hatch. Ensure the seacock is open. Turn on the water pump breaker and the breaker for the salon AC unit. Listen for the compressor to kick in, once it does, the pump should start. Confirm it's actually running. If it is, the way I prime these is by loosening the screws on the pump housing on the front of the pump while the pump is running. It doesn't require loosing too much, just enough to let air escape. Once it starts pumping, water will start shooting out the sides of the pump so have some rags ready. You'll know when it's pumping as there will be an obvious change to the sound of the pump indicating it's flowing water. Then tighten the screws quickly. This is such a common method that some pumps used to come with wingnuts instead of screws for this reason. The only caution here is that there is an o-ring behind the pump housing so don't loosen the screws too much or the water pressure will push the o-ring out of place.

Once the system is primed, you should be okay from then on unless you come out of the water which is the case up north every winter. There is also a marine railway here where boats are slung out of the water and transported over a hill to the adjacent lake which often requires the uninitiated boater to prime their HVAC system afterwards. Those in the know will shut their seacock off ahead of time. This helps prevent having to prime later as it won't let all the water siphon out of the system. There are many hacks and mods to accomplish the same thing, some will tee off close to the pump on the output side with a valve that just needs to be opened for purging.

Hopefully priming will solve the issue. Good luck and keep us posted.