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Hercules Boiler Cleaner

I used this Hercules Boiler Cleaner with Silicone in my boiler this year and I have been experiencing some respiratory irritation which sent me on a tear to check all my vents etc, for possible leaks. The MSDS shows that it has cyclohexamine, which has Toxicity LD50 (rat; p.o.) = 0.71 ml/kg, and Butanamide, 2,2`-[(3,3`-dichloro[1,1`-biphenyl]-4,4`-diyl, which is a California Proposition 65 Carcinogen:


At first I realized that I had put way too much in (whole 32 oz bottle) since the boiler is only 10.8gal and the instructions said 1 qt per every 20 gal. That caused me a LOT of irritation and I have since drained off 5 gal and replaced it with clean water from my water heater.


The other thing that bothers me is that I drew off a small 1 cup sample of water from the bottom of my sight glass and tested it with pH hydrion paper and it looks like the pH of my boiler water is around 6.0 !!! I think this is strange since my tap water tests around pH 8.0 and the Boiler Cleaner itself is supposed to be pH 12.34 with a "slight amine" odor.

Is this stuff safe? And what should I do about the pH? I bought some Arm and Hammer Super Washing Soda, but I'm having some trouble determining how much to add, it is extremely alkaline and I read somewhere that caustic soda may be preferable because it doesn't introduce carbon dioxide into the water.


  • Captain Who
    Captain Who Member Posts: 452
    By Richard B. Carey Hagan, Chemicals & Controls, Inc: ,Hall Laboratories Division


    "The second class of chemicals supply alkalinity to the boiler water. Soda ash (sodium carbonate) and caustic soda, (sodium hydroxide) are used for this purpose. Some types of phosphates also add some alkalinity. Alkalinity in the boiler water has a three fold purpose. First, sufficient alkalinity is required to insure that the calcium phosphate is precipitated as a non-adherent sludge. Next, the alkaline materials prevent the water from dissolving the boiler metal. This is of course, a very slow process; however, it proceeds at its slowest pace at a pH of 10.2. Most boiler water treatments are slightly above that point. Finally, sufficient alkalinity is needed to keep excess silica in solution, where this material is high in the raw water.
    Although caustic may be somewhat more dangerous to handle, it has one big advantage over soda ash. This is in the field of condensate return line corrosion, and will be covered later."

    "If soda ash is used for boiler water treatment it too breaks down in the boiler to form caustic soda and carbon dioxide. This simply increases the corrosion problem, and, if you are using a neutralizing amine it increases your cost. Inasmuch as caustic soda is already reverted to the final product, no carbon dioxide is given off in the boiler. This is of course the advantage of caustic over soda ash."

  • Captain Who
    Captain Who Member Posts: 452
    I guess I should have made this a Question thread. Really was hoping for some input here, even if it is only opinion. Thanks.