Descale Marine AC Unit

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JoeD

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Aug 31, 2005
116
Columbia 34 MKII Smith Point,VA
Have a Flagship Marine FMAC 18,000R Heat and AC unit. The unit needs descaled. Has anyone descaled their Marine AC unit? Have good water flow but is getting hot and shutting down after about 30 to 40 minutes of use. Talked to Teck rep at Flagship and after giving him the readings said need descaled.

Have read many post on the subject but come away a little confused. Some say use Acid some say use Barnacle Buster. Understand there two ways that are best open loop flushing about four hours, Or over night Immersion to dissovle crud then flush with clean water.

So would like to hear from some of you on the subject. Any and all help appreicated.

Thanks,

Joe
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
Suggest the use of RydLyme, an inhibited/buffered acid. Disconnect the intake line and connect to bucket, disconnect the AC discharge and connect to the same bucket as before. Add Rydlyme and recirculate for a few minutes, then shut down to soak, etc.

http://www.rydlymemarine.com/ ... but you can find better prices from distributors.
MSDS: http://www.rydlymemarine.com/pdfs/RYDLYME MARINE MSDS JAN2008.pdf .... active ingredient is 10% Hydrochloric (muriatic) Acid ... buffered.

Of course you can use diluted Muratic (hydrochloric) acid but you risk dissolving of the base metal. Forget about vinegar (acetic) acid, oxalic acid, etc. as they dont have the potency of HCl or other commercial inhibited boiler descalers.

Rydlyme is also great for descaling marine engines, heat exchangers and removal of hard growth from through hulls and their valves.
 
Oct 3, 2008
325
Beneteau 393 Chesapeake Bay
Suggest the use of RydLyme, an inhibited/buffered acid. Disconnect the intake line and connect to bucket, disconnect the AC discharge and connect to the same bucket as before. Add Rydlyme and recirculate for a few minutes, then shut down to soak, etc.

Of course you can use diluted Muratic (hydrochloric) acid but you risk dissolving of the base metal. Forget about vinegar (acetic) acid, oxalic acid, etc. as they dont have the potency of HCl or other commercial inhibited boiler descalers.
I had a similar problem and did let it soak overnight with undiluted plain white vinegar. I chose this approach first, since it is much milder, as said above. However, it did seem to work and I have not had problems since.

Paul
 
Nov 26, 2008
1,970
Endeavour 42 Cruisin
I don't have any suggestion on descaling. But I do have a suggestion on prevention. My A/C thru hull has a valved tee fitting with a hose barb. The hose barb has a garden hose adapter on it. When leaving the A/C sit for any length of time, I run fresh water thru the system via the garden hose adapter to flush out the salt water. No scale buildup.
 

JoeD

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Aug 31, 2005
116
Columbia 34 MKII Smith Point,VA
Descale

Thanks for the information. Did contact Rydlyme for a distributor in VA or MD. That looks like the best that have seen so far. If you know of one please let me know.

Will let you know how it works.

Joe
 

capta

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Jun 4, 2009
4,909
Pearson 530 Admiralty Bay, Bequia SVG
I had this problem some years back and a refer tech I trust implicitly suggested Mary Kate On & Off hull & bottom cleaner and it does the job wonderfully in just a few minutes. Exactly the same as richh suggested but only for 15 to 20 minutes and you're done. Read the cautions on bottle as acid is involved.
 
Feb 26, 2004
23,003
Catalina 34 224 Maple Bay, BC, Canada
I had this problem some years back and a refer tech I trust implicitly suggested Mary Kate On & Off hull & bottom cleaner and it does the job wonderfully in just a few minutes. Exactly the same as richh suggested but only for 15 to 20 minutes and you're done. Read the cautions on bottle as acid is involved.
Wow. What a good idea to never use this stuff. I tried it once and almost died!

If you want to clean stuff up, then use FSR, same material, a lot less toxic to your lungs. why? 'Cus it is a gel, not a liquid.

Otherwise, regular cleaning might do the trick. i know, easy for me to say...
 
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