AC coil cleaning with Phosphoric acid

[mobern]

I'm planning to clean the condensing coils of my CruiseAir AC using Klean Strip Phosphoric Prep & Etch which is between 35.0 -45.0 % phosphoric acid. I have rigged a recirculating loop with a small bilge pump.
My questions are :
1. How much to dilute the acid ?
2. Is it better to let the diluted solution rest in the coils for any length of time?
3. Using baking soda and fresh water to neutralize the acid, how much of each?

Any experience with any form of phosphoric acid used in this way would be greatly appreciated.

[thinwater]

Originally Posted by mobern

I'm planning to clean the condensing coils of my CruiseAir AC using Klean Strip Phosphoric Prep & Etch which is between 35.0 -45.0 % phosphoric acid. I have rigged a recirculating loop with a small bilge pump.
My questions are :
1. How much to dilute the acid ?
2. Is it better to let the diluted solution rest in the coils for any length of time?
3. Using baking soda and fresh water to neutralize the acid, how much of each?

Any experience with any form of phosphoric acid used in this way would be greatly appreciated.

Why would you chose a product designed to etch metals? Do you know what metals are in the system?

I would use Barnacle Buster, RydLyme or CLR. Then follow the instructions.

If the problem is biological growth, close the through hulls for a few days every few weeks and that will kill everything.

https://www.practical-sailor.com/iss...s_12249-1.html

[mobern]

I've used Barnacle Buster and I saw that it was <50% phosphoric acid on the products SDS information sheet which lead me to ask, what is the difference ?
Thanks for the PS link, I'm a subscriber but having trouble downloading the article.

[svHyLyte]

Originally Posted by thinwater

Why would you chose a product designed to etch metals? Do you know what metals are in the system?

I would use Barnacle Buster, RydLyme or CLR. Then follow the instructions.

If the problem is biological growth, close the through hulls for a few days every few weeks and that will kill everything.

https://www.practical-sailor.com/iss...s_12249-1.html

Excellent advice. Having used both Rydlyme and Barnacle Buster I suggest the latter is somewhat preferable. Counter circulate (in the discharge side and out the input side of the unit) with fresh water before running your solution (in the same direction) to clear out silt build up at the start.

FWIW

[billknny]

Originally Posted by mobern

I've used Barnacle Buster and I saw that it was <50% phosphoric acid on the products SDS information sheet which lead me to ask, what is the difference ?
Thanks for the PS link, I'm a subscriber but having trouble downloading the article.

I'll second the comment about using a product that is designed for what you want to do. Yes, Barnacle Buster CONTAINS phosphoric acid, but that is NOT the only thing it contains. (The MSDS only lists the "hazardous ingredients"). Just as a guess, surfactants, chealating agents, corrosion inhibitors...

I have used a couple of products made by TRAC Ecological, and they are well formulated and do what they are supposed to do. If you are a corrosion chemist, then go ahead and make you own mix... otherwise... well...

Your AC Coils are almost surely made of copper...not a good material to be soaking in plain a 40% Phosphoric acid DESIGNED to etch metals...

[mobern]

Thanks to all.
I'll continue cleaning with the marine products designed for this application.

[Moltensurf]

Originally Posted by mobern

I'm planning to clean the condensing coils of my CruiseAir AC using Klean Strip Phosphoric Prep & Etch which is between 35.0 -45.0 % phosphoric acid. I have rigged a recirculating loop with a small bilge pump.
My questions are :
1. How much to dilute the acid ?
2. Is it better to let the diluted solution rest in the coils for any length of time?
3. Using baking soda and fresh water to neutralize the acid, how much of each?

Any experience with any form of phosphoric acid used in this way would be greatly appreciated.

I would not clean your ac coil with acid. My dad was an AC specialist. the acid molecule is smaller than a water molecule. The acid will make it into little holes and such and you will not be able to get it all out. It will ruin your coils. My dad and I would spray the coils with water.
The type of coils I am referring to are fin coils

[Parrothedd]

Use Barnicle Buster. It’s safe.

[Squanderbucks]

I don't think the OP is talking about cleaning the cooling fins of the system but the internal salt water coil. The aluminum fins on the exterior definitely do not get any acid put on them. If they are dusty and clogged from not keeping the air filter up to snuff there are spray products you can use with a chip brush available in a home goods store that is safe foe those little fins.