Cleaning AC water supply

My front and rear AC share the same strainer and pump and my front AC flow has dropped down to almost a trickle. Seems I need to flush the system with muratic acid as I recall. Sump pump in a bucket- and a return line maybe? How much, what % water/ acid mix? Water or acid first in the bucket? Is it OK to flush it backwards and would this help? Thanks to all.

Professional chemicals can be purchased.

ALWAYS Add the Acid to the water.

Do wear acid resistant gloves and eye protection.

I have used a 50-50 mix on my Perkins H/E's.

Steve, I have always got very good results simply by backflushing the system with water. I just take one of those "cone nozzles" that cost about 2 bucks and stick it up the hole on the outside of the hull and flush all the way thru. Beware because there is some nasty **** that comes out on the other end.




-- Edited by Baker on Monday 19th of July 2010 11:25:45 AM

Steve, Larry B. posted this on another forum, I don't know what the dilution rate was

" I have a 120 VAC basement pump with 3/4" hose fitting on it. Bilge pump would
work fine as well. AC RW hoses are 5/8". I put about a gallon of diluted
muriatic acid in the bucket; remember the mnemonic AA- add acid. Submerged the
pump and plumbed it through the appropriate adapters to the RW in line of AC
unit and ran the out line to the bucket, tie wrapping the return hose so's it
wouldn't get away under pressure. Left the ER and applied power to pump for 5
minutes; did the same on the remaining units. Irrigated pump and hose with
fresh water and stowed.
After 10 minutes, with rubber gloves, I reconnected all RW lines and ran
system. #2 is back to spec.
Steve W.

What dilution did you use for the acid?

I have heard of some folks dropping a chlorine tablet in the strainer for an hour or two. The type you buy at a pool store.
Don't leave the tablet in the strainer without the pump running, it could melt the plastic basket.

Chlorine won't affect a plastic basket, nor a SS one significantly for that matter. I use Clorox toilet tank tablets, and break them up before use. Put about half of one in the strainer and leave it. It'll dissolve over the next day or two during the summer. I also put a strip of copper foil in there which helps as well. The toilet tank tablets last longer than pool tablets and have inhibitors in them to help with corrosion problems.

Keith, how often do your pumps fail???? The only reason I ask this is because I know some folks that brag about doing the same thing while complaining that their pumps only last them a year or so.... Do you find yourself replacing your pumps more often than "normal"?

My AC cooling water pump failed once in 9 years, maybe 2 years ago. Who knows how old it was at that point. I keep a spare on board just because of the consequenses of not having AC in our climate!

It doesn't take much chlorine (sodium hypochlorite) to keep the system clean. On ships and larger yachts we have systems that produce it electrolytically and continuously inject it in the seawater circulation systems.

The concentration is only about .5 ppm

I had the bottom pressure washed about a month ago, it was covered in green slime. So, I figure, if the slime is on the bottom, it should also be in the raw water pump, heat exchangers, etc. If so, what about a chlorine tab in the sea water strainer for this? Possible damage anywhere? Hot water heater damage?
Mike
Baton Rouge

I'm no expert, but I wouldn't put any chemical in the engine raw water cooling. To many hoses and other things that could be damaged. Green slim would probably need light to grow and there should be an absence of light in the interior workings of your plumbing. I plan on routinely flushing my engines with fresh water prior to leaving for extended periods. A fresh water flush is easy to install and according to some "experts" is the best single thing you can do for your raw water cooled engine to maintain it's longevity.
The only other plumbing system on the boat that needs attention that I'm aware of is the air conditioning. I've heard a chlorine tablet twice a year should do it, perhaps more in warmer water. The hot water heater is no different than in your house and shouldn't have anything growing in it. A table spoon of liquid chlorine in your water supply should take care of any smell. Just be sure and fill the water tank.

"I plan on routinely flushing my engines with fresh water prior to leaving for extended periods. A fresh water flush is easy to install and according to some "experts" is the best single thing you can do for your raw water cooled engine to maintain it's longevity."

Somehow I don't believe either one of you has a raw water cooled engine.

"I figure, if the slime is on the bottom, it should also be in the raw water pump, heat exchangers, etc."

You won't find green slime but you might find a good crop of little shelled critters in your warm water area. You can keep them at bay with half or a quarter of a pool tab in the strainer, run the engine to circulate the treated water.

This isn't the most environmentally acceptable method since it's not nice to chlorinate your marina.

Rick,Mine are raw water cooled, I should have added through a heat exchanger. Correct, no raw water inside the engine.

A word of caution here: muriatic acid does remove calcium build-up and doubtless other unwanted matter too. However, it also reacts with the solder used to join the copper cooling coils of most a/c units. I would seriously consider using RydLyme or similar. My setup of a small manual bilge pump, a plastic bucket, and two hoses makes it a breeze to recirculate through each a/c unit in turn.

Flush the system with CLR or Redlyme. Chuck

-- Edited by Capn Chuck on Friday 23rd of July 2010 05:08:10 PM

CLR looks like it's easy to get. So how do you use it to clean the AC system. Disconnect from the strainer, put a hose on the inlet of the pump and allow the pump to suck in from a bucket??
How long do you let it stand in the system?
Can CLR be safely used to clean the toilet in a Vac U Flush system?

-- Edited by timjet on Saturday 24th of July 2010 12:09:56 PM

Steve,

I did the acid flush thing last year, and it made a huge difference in the performance of my AC systems. I have owned the boat since 2004 and had never done it, and have no idea of how long since it had been done. Here are the instructions I used, sent me on another list....


Condenser Coil Cleaning


1. With the system turned off at the circuit breaker on the ship s panel,
disconnect the inlet and outlet connections of the condenser coil.


2. Use chemical resistant hoses (MAS white PVC 5/8" I.D., etc.) to connect
the inlet of the condenser coil to the outlet of a chemical resistant, submersible pump (MAS P-500 pump, etc.) and let the hose connected to the coil outlet flow freely into the container mentioned below.


3. Place a strainer or piece of screen over the inlet of the pump and
submerse the pump into a container filled with a 5% solution of muriatic or hydrochloric acid and fresh water or use a premixed over-the-counter solution. Use a large container as possible to hold the solution (5-25 gallons). CAUTION: avoid spilling or splashing the solution. Always add acid to water. Follow all warnings and recommendations given by the manufacturer of any acids or pre-mixed solutions.


4. Power the pump and circulate the solution through the condenser coil for
15-45 minutes depending upon the size of the coils and the extent of the contamination. Visual inspection of the solution in the container should indicate when the contamination removal has stopped.


5. Circulate fresh water through the coil to flush any residual acid from
the system.


6. Restart the system and check operational parameters to ensure thorough
cleaning has taken place. Additional cleaning may be necessary with extreme contamination.


WARNING: For the purpose of protecting the environment, dispose of any
contaminated acid solutions in
accordance with federal, state and/or local regulations.


There is also a recommendation to cycle a reverse cycle unit to heat once a
month to exercise the reverse valve.



Few notes here. I used a 5-gallon bucket and it was almost too small. This stuff foams up like crazy as it eats away at the crud coming out of the coils. Fortunately I had another 5-gallon bucket handy and was able to scoop some of the foam into it.


Make sure the area is well ventilated.


I just used a cheap bilge pump and the existing 5/8 hoses. I had planned on replacing them anyway, so just used them for the flush then installed the new hoses.

Hey Ken,
it's great to see you on the board. I have the necessary supplies and will work on it this evening.

I just had my a/c cooling sytems flushed as I was having some overheating issues with my Cool Breeze 12000 btu unit. The tech used a product called Barnicle Buster which was mixed with water (not sure of the ratio) in a 5 gal. bucket, then a fairly good sized bilge pump connected to some hose which were connected to my a/c's, lowered into the bucket and ran for about 12 hrs (overnight).

The end result was very successful as the unit now runs cooler and does not "cycle" on and off like it used to.

Barnicle Buster

Always best to use a product created to work a problem , rather than becoming a chemist and praying for results.