Marine a/c water pump

[BobandJoann]

We are replacing our marine a/c water pump which is 320gph. We are looking at a pump that is 300gph & a pump that is 500gph. We do not know if the pump we are replacing is the original one. Our question is should we go with the 300 or 500?

[jstevens]

The answer is in the A/C unit the pump is servicing. As long as the water requirement for the A/C is below 300 gph you should be OK. 500 gph sounds like a major over kill. There have to be other options.
The water flow requirements for the A/C should be stamped on the manufacturer plate or in the documentation, which is likely available online. Better yet call or email the A/C manufacturer and get their recommendation.

John

[BobandJoann]

Unfortunately the company that made the a/c unit is out of business. There is nothing in the literature and nothing stamped on the manufacturer plate.

[GordMay]

What is the make, model, and BTU/H capacity of the AC?

[BobandJoann]

The make is Polar Bay Air, the model is SLW10DH-1 and 10,000 BTU.

[a64pilot]

10K is actually pretty small, I'd bet your fine at 300.



Sent from my iPad Pro using Cruisers Sailing Forum

[BobandJoann]

Thank you to all who replied to my question. Your response is appreciated!

[pwmullins]

I have a brand new 400 gph pump manuf. by Little Giant, above the water line type that I bought for a dual system and it wasn't big enough. I replaced it with a 600 gph pump of same module.
Paid $270.00 for it and will take $150.00 plus freight. If interested email pwmullins@aol.com

[sailnow2011]

March LC pumps are best. Mine has been running daily for 2 years with 0 issues.

[BobandJoann]

We have decided to go with March 300gph.

[MCOS]

Originally Posted by BobandJoann

We are replacing our marine a/c water pump which is 320gph. We are looking at a pump that is 300gph & a pump that is 500gph. We do not know if the pump we are replacing is the original one. Our question is should we go with the 300 or 500?

Original systems are generously configured with expected high parameters as performance standards, IE temperature high in cabin and and high water temp. Since the average real world usage is far below the extreme that the system may occasionally face, the downsize from 320 to 300 should have little to no adverse effect on the overall performance. I would opt for the 300 gph.

[sailnow2011]

The only issue with 300gph is if you have a long run, or put in any elbows, flow will suffer. Better to be too high flow then too low.

[BobandJoann]

Originally Posted by MCOS

Original systems are generously configured with expected high parameters as performance standards, IE temperature high in cabin and and high water temp. Since the average real world usage is far below the extreme that the system may occasionally face, the downsize from 320 to 300 should have little to no adverse effect on the overall performance. I would opt for the 300 gph.

Thank you!

[ramblinrod]

Originally Posted by BobandJoann

We are replacing our marine a/c water pump which is 320gph. We are looking at a pump that is 300gph & a pump that is 500gph. We do not know if the pump we are replacing is the original one. Our question is should we go with the 300 or 500?

All pump ratings are based on open discharge at rated voltage. The actual output will vary greatly depending on system head loss (caused by flow resistance and lift requirements), as well as actual voltage.

The original system was designed with these considerations in mind, and there was a good margin of safety built in, to allow for these variations.

Depending on the system, the actual flow of the original may be only 150 GPH and the replacement 148 GPH (for example), depending also on the shape of the pump curves.

This variation may be equal to like a 0.25 Vac drop in supply voltage.

For all of these reasons, if the 320 GPH pump worked fine, I'm 99% sure the 300 GPH pump will as well.

Disclosure: I sell and install Marine Air Conditioning systems. The post is offered as free advice and is not intended to solicit business.

Ramblin Rod
Marine Service Provider
About Sheen Marine

[wesevans]

With A/C other things being equal bigger is better. The bigger pump will have higher pressure if the hose diameter is the same.