Air Conditioning water flow restrictions..... AFTER strainers

[NYSail]

Hello all

I have two units that are fed sea water from a single March Centrifugal pump. Last weekend I had an issue with clogged strainers; the inside as well as the outside thru-hull. Once I cleared the grass system worked fine with good water flow out of both exit thru-hull fittings. However during the clearing process when I was cleaning out the eel grass I fit my hand pump on the intake to the system March Centrifugal pump making sure the system was not blocked from that point. I went to pump and it felt completely blocked and could not get air or fresh water through.... It actually built up pressure and sprayed the boat when I removed my hand pump. Subsequent to that I had cleaned out the grass, reattached the hoses and all worked great with perfect water flow. At first based on my limited knowledge I though there must be some kind of internal valve that opens and closes based on whatever..... again my basic ignorance of the systems. So now I am reading about winterizing and it say that you can easily pump antifreeze through the system. I am new to a/c winterizing...... Am I missing something?

Thanks
Greg

 

[dlochner]

Did you try to pump air through the pump? Or after the pump?

If you did it before the pump then you would be forcing water through the pump vanes and that would have to turn the pump motor.

I have water cooled refrigeration, when I winterize I use the refrigeration pump to pump antifreeze through the system.

 

[NYSail]

I was doing in before the pump... with the directional flow of water. It was my understanding (now after some reading) that water can flow through these pumps as vanes dont touch sides inside.

 

[dlochner]

In a centrifugal pump the chamber where the vanes are located is not a perfect circle, this allows water to enter and leave. How much room is there between the vanes and the side walls? Not very much I would think, the greater the distance between the vanes and the sidewalls the less efficient the pump.

I would simply remove the hose from the sea cock, stick it in a bucket of AF and run the AC until the system was flooded with AF. The refrigeration pump on Second Star draws from the galley sink drain, so I close the seacock and pour AF down the drain and let the pump suck it out. You may be able to do the same depending on where the inlet is.

 

[thinwater]

Centrifugal pumps have considerable free space through the impeller, even when no moving. The operation is TOTALLY diff-rent from vane pumps. There is some restriction, but you can pump through them.

But why aren't you using the pump to pull the AF in? Just add a tee and a valve. Easy.

 

[NYSail]

Last season a friend that works in the yard did my a/c. he used his hand pump.... opened up the sea cock, then pumped the antifreeze backwards through the system from the exit thru hulls on the side of boat. the AF poured out the intake and he was done.... looked pretty simple.

 

[quadrille38]

There are a couple of really good threads in the archives that talk about winterizing ac units.
Take a look