Air conditioner raw water Coil flush

[Capt Robbie]

I have noticed in the area I sail, that alot of my fellow boaters have to flush there Ac unit coils a few times during the season due to build up in the Ac water jacket coil. There units start to lose water flow and effecentcy even though the strainers are clean. I don't think boaters realize how important it is to keep the system clean, and not just the condenser coil,air filter, and strainers.

When I installed my Ac unit I decided to add a Tee fitting with a shut off valve in the inlet hose just after the seacock so it would make it easier flush and to winterize at the end of the season. This was a simple modification to do.

Installed tee fitting inline with raw water hose, then from the tee added 4' length of clear hose long enough to reach the sink with a shut off valve at the end.

Now to flush system:

Shut off the Ac unit. And Simply open the shut off valve to allow the raw water to fill the clear hose, and then close the valve when line is full. Next shut off the raw water seacock. Fill the sink with fresh water and a ounce or two of boat soap, then place the clear hose into the sink. Turn on the Ac unit and open the clear hose shut off valve. Alow the Ac unit to draw the soapy water into the system. Shut off the unit and shut off the clear hose valve, let the solution sit for an hour or so. Sometimes I let it sit for the week to really clean the coil.
Open the raw water seacock and Run the Ac unit as normally, the system is now flushed.

I do this just about every time I use the Ac because it's so easy to do.

I do the same procedure when I winterize boat before its hauled, except that I add non tox antifreeze at the end.

 

[Rich Stidger]

What is it exactly that builds up in the coils? I flush my A/C at the end of the season with fresh water for about 10 minutes before I let it suck in antifreeze. I have never noticed any loss of water flow during the season

 

[Capt Robbie]

I have never had the issue myself. However when others flush the system it looks like muddy water. Some people sometimes have to use some pretty nasty chemicals to clean them out.

 

[Ron20324]

I was just this last Saturday at a seminar about refrigeration and air conditioning. They suggested running vinegar into the AC's coils to kill the algae. Leave it in about 20 minutes then flush it out. They say to do it once mid-season, then when winterizing. Also, remember to clean the air filters that serve the compressor fans. They can't always be seen!

 

[Dan_Y]

Are there any issues with the vinegar and the metals used in the tubing or joints? I know first hand even a mild solution of vinegar will dissolve certain plating off of a copper substrate in less than half an hour... Would salt away or a flush used on heat exchangers be safer?

 

[Capt Robbie]

Great tip with vinager!
I always used bleach diluted with hot water. Never knew vinager killed algee and better for environment.
Do you know if you use straight vinager or is it diluted?

 

[Rick Webb]

I know some folk who periodically put a quarter of a pool tab in the strainer. It does a remarkable job of cleaning the whole run and makes a huge difference in the flow. I would not leave any in the strainer. I would probably be reluctant if the discharge fitting were bronze don't think it would hurt any of the plastic or stainless though. The first one I saw do it the water just dribbled out after fifteen minutes it squirted out like a water hose .

 

[thinwater]

Really, you will kill all of the algae by closing the valves for a few days (no oxygen, copper ion in a confined space). Leaving a zinc anode in the inlet strainer (not bonded) works too; this is often done in large ships.

I think you are over complicating this with chemicals.

 

[Terry Cox]

Huh. Never had a need to clean our heat pumps since we purchased Belle-Vie in 2002. Water flow always strong whenever we use the system, which is a few times during the winter months when we stay on the boat at the dock. Maybe something to consider. I do check the sea water strainer maybe once a year and it normally comes out clean when I do.

 

[Capt Robbie]

Like the idea of putting a zinc in the strainer

 

[Rich Stidger]

Huh. Never had a need to clean our heat pumps since we purchased Belle-Vie in 2002. Water flow always strong whenever we use the system, which is a few times during the winter months when we stay on the boat at the dock. Maybe something to consider. I do check the sea water strainer maybe once a year and it normally comes out clean when I do.

Ditto for me except I date back to 1998.

 

[Dan_Y]

I assume the zinc in the strainer is most effective in salt water? I'm clueless as to how this works.

 

[Gunni]

Zinc oxide leaching off an anode is a biocide without the corrosive pH problems.