Hello Steve,

This is a 25 year old system.  One water pump tees off to two Marine Air CM16H units.  Water flow at outlet of aft unit has always been less than forward unit [last four years] but in last two weeks is markedly less.  Aft unit starts normally and begins to cool, but trips the breaker after less than five minutes.  Forward unit functions normally.  The inlet seacock, strainer and cooling water pump are all located within ten feet of the forward unit.  The aft unit is about 35 feet away from the forward seacock/pump/strainer.  We clean the strainer weekly with current high water temps, and notice barnacle growth inside the strainer in last two weeks with sea water temps now above 80 degrees F.  We also clean the air filters on a regular basis.  Have done no other maintenance on either unit, except to replace one thermostat sender.  Boat is in SC in the winter/spring and New England in summer.  Assume we have a marine growth problem in hoses and/or condenser coils.  Read your cautions about acid cleaning.  Spoke to Marine Air service four years ago and they said maybe not to acid clean units because of age [25 years now] and cleaning might start leaks.  So what to do?  Can I use something Barnacle Buster, PhosphoRic, or Rydlyme safely?  Could that solve the problem, or am I dealing with possibly some other issue?  

Thanks in advance,  George

Hi Steve,

Thanks for getting back to be so quickly.  Yes, I hear a bit of crunching when compressing at least one of the hoses, so will give the treatment a try. 

George

Post edited 2:07 pm – June 6, 2011 by Steve Pooler

GeorgeH said:

Hi again Steve,

If I go the route of replacing the hoses, what type do you suggest? Currently have 3/4" wire exhaust hose on runs to both units, and then 5/8" wire exhaust hose from units to overboard discharge.…You can pretty much use any kind of hose as long as it does not let light in…I prefer Black Rubber over a Vinyl or PVC based hose…Barnacles seem to grow quicker with light & they also seem to love to stick to PVC or Vinyl…  

Also, on my aft unit, water flows overboard there even when only the forward unit is running.  So I assume that water is running through the aft condenser coil, but not heated, so perhaps there is marine growth there because of that?…Yes that is true…But in over 25 years I have only seen barnacles grow in a condenser that the unit had not worked in years but others supplied by the same pump did…Hard Water Scale is usually the problem in the condenser itself.

Thanks again, George

 

This link will tell you why water pumps thru that aft unit with only the fwd unit running: http://marine-ac.com/marine-ac…..mp-relays/

 

Steve~