Question About Corrosion Prevention.

I am new to hydronic heating. In April I purchased a house with two types of wood heat. A wood stove insert and a Rite Way wood boiler connected to a 1500 gallon heat storage tank for my in floor heat. The in floor heat is also tied to a propane hot water heater so you can either use propane or wood to heat the floors. In September I fired up the boiler for the first time after refilling my storage tank. Turns out the previous owners drained it and left it empty for about 7 years. The following day I walked into my garage where the boiler is and found the tank had a major leak. There was a good 2 inches of sludge left in the tank for those 7 years which ate holes into the bottom of the tank. I cut the bottom of the tank off, welded a new bottom on, refilled the tank, fired it up once more and now the system works great.

My question is this: Besides not emptying the tank and leaving it with sludge in the bottom to rust it out, what is best to add to the water to prevent corrosion of the steel and copper?

Maple 1:

It is an open tank as far as I can tell. There is a pressure gauge/temp gauge on the boiler. The pressure never goes above 0. The tank is made of 10 gauge mild steel roughly 8 feet long, 8 feet tall and 3 1/2 feet wide. The top of the tank is removable. There is no gasket around this lid. There is also a fill hole on top that had a funnel with a plastic softball in it to keep dirt out I think. I left it as is.


Mustash 29:

Thanks, I'll check that out.