Fernox 56599 F1 500 ml Central Heating Protector

From what it says on the bottle seems to be good stuff have it in the boiler for about five years and water is crystal clear, so decide to add some more. Seller shipping was a bit slow but the price makes up for it. I was not in a rush to receive it so five stars from me. Use a cleaner first drain system than ad this one. If you shutting your pump for the summer this will stop pump from seizing.

Good product. Use it regularly. Can tell difference.

Time will tell if it works. I would have to do a partial drain of boiler water to check for rust cause i have 2 cast iron radiators in my basement, the rest of my rooms have baseboard elements which are copper

Keeps the boiler water clean letting the rust settle down but the steam has an odor to it so 3 stars

Best price.

Had closed loop geothermal wells that went acidic and destroyed my pumps. Added 3 bottles of this to the solution, ran the replacement pumps for 30 min and to my amazement it saved me from having to have a company flush my wells. Balanced the PH out perfectly.

I've been very impressed with this additive to my hydronic heating system. Before, I was getting a lot of rust and clogging of my filter in my water heater (yes, I'm using a water heater to heat my floor). This product was expensive, but the rust I had been getting is now gone and my water heater is preforming much better. The ferrous metal in the circulators had been rusting and impairing the water flow. Now, I'm very satisfied with the how it's flowing and the water color is no longer rusty.