Cleaning HE with phosphoric

[Bill Root]

I want to clean the raw water heat exchangers today. I have been unable to find oxalic acid anywhere (tried hardware, HD, Lowes) to make the DD mix, but I did find the Kleen Strip phosphoric acid product that many have recommended at HD. My question is do I use this product full strength or do I dilute it? I've searched the forum posts, but can't find an answer to this question. Thanks.

 

[REBrueckner]

Karl's instructions are in Frequently Asked Questions:

http://www.samsmarine.com/forums/showthread.php?t=1483

 

[LUV'N LIFE]

Bill, I found oxalic acid at Ace Hardware in the paint section. It is Ace brand in small boxes, powdered and called Wood Bleach.

 

[Bill Root]

Thanks Rob & frank. My HE's are off. I will be dunking them. Reading Karl's post sounds like about 1 gal Phosphoric to 3 gal water.

 

[Timm]

Your local West Marine should carry oxalic acid as well. If not on the shelf, it's available as a back order.

 

[REBrueckner]

I also used to find oxalic acid in my Local Bridgewater,NJ, ACE hardware....
but I don't know how appropriate it is for HE cleaning...never used it that way, just to bleach wood prior to varnishing.

 

[MikeP]

"but I don't know how appropriate it is for HE cleaning..."

Per the DD service manual, a solution of Muriatic acid, Oxalic acid, and water is specified for cleaning the HEs.

 

[REBrueckner]

"Per the DD service manual, a solution of Muriatic acid, Oxalic acid, and water is specified for cleaning the HE.."

...oh yea, we have seen that here before.....man that SOUNDS aggressive...but with appropriate concentration and duration of application it must be ok...

 

[MikeP]

It's what I have done both times I have pulled/cleaned them. It doesn't take long!

I would not use the DD "mix" for "in-place" cleaning but I have never used that method. I keep thinking I'll try it but I like having the HEs out, in my hands to examine/clean.

 

[Bill Root]

I did the job the old fashioned way today. I mixed a solution of a gallon of the Kleen Strip phosphoric product with 3 gallons water in a large bucket. I stood the HE on end in the bucket (my raw water HE's are large cylinders 6" in diameter and 38" long), and used a large jar to scoop solution out of the bucket and pour it through the HE. It took about 30 minutes of scooping & pouring to remove all the old rust and scale and for the bubbling to stop. Certainly not a fancy system or how a pro would do it, but it worked great for me.