Silver King HF5SK471 1 Quart Hydronic Formula #5 Hot Water Systems Boiler Cleaner Inhibitor With Silicone SK-471

I have been using this for a very long time. It turns all the orange rust deposits in your boiler black and stops any further corrosion. It helps with heat transfer as well.Sincerely,William McCormick

Great product. Not happy that it was a buy again and Hardware USA sent me the wrong product ,which I had to pay almost as much to ship back as the 2nd buy again. No more Hardware Usa for me.

I have used this product for the past 3 years in my Peerless 3 section boiler. This is the 4th year I am adding the product according to directions. I use the full bottle.As my photos show, the inside of a Honeywell zone valve and a Taco 007 pump are coated with a black film. I was under the impression this product kept the system clean and lubricated. The little water I drained out of the system when changing the pump and zone valve did not look dirty. Slightly brown. I don't think this is a good boiler cleaner. But I do like the idea of a silicone lubricant kept in the system throughout the year.I have no way of telling how bad the pump and valve would have looked if I had not used the product, or had I used a different product.

I have old Entran tubing in my hydronic floor heat. I use the silicon additive in hope that it will extend the Entran life. It appears to be working so far.