Refrigerator/Freezer Water Flow

[rgtet]

I don't seem to have any documentation relating to my refrigerator/freezer unit and was hoping for some advice. When I was a powerboater, my refrigerator was a dual voltage unit, much like a dorm refrigerator in size (pure air exchange heat transfer across the coils). With my current unit, as I'm guessing nearly all of you have, it has a water pickup for heat exchange. As long as my cabin is cool (a/c running for the weekends when we're aboard), the units stay very cold (cold plate generates frost). When I turn the a/c off during the week, yet leave the refrigerator on, everything heats up (cold plate is warm to the touch). It is obvious that there is no heat exchange with the water pickup.

When I first bought the boat, there was very occasional water flow (evidenced by the discharge stream), but now I'm at zero flow. I have cycled the seacock and cleaned the strainer (I felt a small amount of water flowing through the strainer after replacing the strainer and opening the seacock, but there was still no overboard discharge), but not sure of the next step, short of calling the a/c guy at $130 just to show up for a look at the system.

My questions are thus: Should I expect much water flow for the refrigeration unit (comparable to the a/c)? If so, what is the best way to flush the water system to restore the cooling flow and should I expect it to stay cold when the cabin temp goes up during the summer (temp ~90-95 on days when we're not there)?

All of my other pickups have correct water flow. The only problem to date is the refrigerator/freezer. Thanks for any guidance and help you can provide.

 

[Bill Roosa]

Hey rgtet
You should indeed have water flowing. Are the AC and reefer water cooling systems plumbed together? Could be three things, clogged lines, loss of prime, or bad pump. You can test the pump with some hose and a bucket. Take off both pump hoses and run a known good hose from a bucket to the pump intake. You may have to prime the hose to get water to flow. If the pump checks out (1is gal/min at least) then take the hose off the seacock and open the valve. Water should run full stream. Attach the hoses in order and recheck. If you don't get water at some point that is the hose that need attention. If you get to the pump inlet and water is only flowing a little you may have the pump located to high in the system (think about when the boat is heeled also) for it to prime itself. If you have water at the pump the connect it and turn it on. there should be water flow. Continue to connect the plumbing pieces in order and confirm there is water flow with the pump on. In all cases you will have the outlet above the waterline and have to have a pump to move the water. The pump should be below the waterline however at all angles of heel to make sure it is primed.
I had that problem on my 37.5, when heeled to starboard the pump was above the water line and when it cycled off it lost it's prime and stopped pumping.

 

[rgtet]

Bill: Thanks for the advice. The AC and reefer are NOT plumbed together. Each has it's own seacock, strainer, pumps, piping, and discharge. The reefer pickup is within 4 inches of my engine raw water pickup and there was water flow through the strainer after I cleaned it, so I don't think that I have a loss of prime. I will have to check the pump, though.

To flush the lines to clear a blockage, what is the best way to do so? I was planning to do so this season, b/c the suspended sediments in/around our slips has been rather high this year. I've been cleaning strainers far more frequently this year than in the past, but the filter elements in the strainers are too big to catch a lot of the fine-grained sediments (and if they were appropriately sized, would have too high of a delta P across the strainer).