Anti-rust additive for steam boilers

drew1942

I need to find a good anti-rust additive for an old Weil Mcclain Steam boiler. I use city water in Ann Arbor Michigan. Anyone with any ideas?

SWEI

Rust is not normal. How much water is the boiler using?

BobC

After addressing any water use issues flush the boiler out and try Rectorseal Steamaster tablets. I've used it for a couple of years now and the water in my boiler is clear of any residue.

Do not follow the instructions that say to use four tablets, one or two is enough for any residential boiler.

Bob

drew1942

Thanks to both SWEI and Bob C for your comments. I do not lose much water except when it goes well below 0 degrees. I have seen your more detailed comments. In my location no one has the steam master tablets but they have two other products by Rectorseal. One is Rectorseal 8way and the other is Rectorseal seal master. Can I use one of those instead?

SWEI

8-Way is a treatment for hot water systems. Not familiar with the other one.

Rhomar also makes some steam treatments http://www.rhomarwater.com/products/residential-steam-system/

BobC

Supplyhouse has them available -

http://www.supplyhouse.com/Rectorseal-68732-Steamaster-Tablet

Bob

ChrisJ

I don't think I've ever heard of a steam system that was rust free? Even with water treatment the mains and radiators are still going to produce rust.

That said, I use Rectorsteam Steamaster and typically run a stronger dose than most. I run 2 tablets in a WM EG-40 boiler. Most guys run 1.

When you get the bottle completely ignore the instructions. I know that sounds unwise, but the instructions apply to commercial boilers or something, whatever it is it's not a small residential boiler. If you do follow them, it won't harm anything but you will find your boiler pukes all of it's water up into the mains.

Thanks to everyone on here emailing Supplyhouse they finally started carrying them a year or 2 ago.

http://www.supplyhouse.com/Rectorseal-68732-Steamaster-Tablet


Whether or not your boiler will tolerate 1 or 2 tablets depends on your water quality and how well the boiler is piped. If you feel lucky, toss two in and see what happens. If there's a problem you'll need to drain some water out and add fresh water back in. If you want to play it safe, use 1 tablet.

Before using it, my water was always nasty rusty brown. While using the Steamaster, my water is always purple and I get a small amount of rust out of the rear section by the return line, likely from the rest of the system when I clean the boiler out in the spring.

I'll never run a steam boiler with water alone again.

ChrisJ

And, I just noticed Bobc already provided you with all of this info. I'm sorry Bob, didn't mean to step on your toes.


P.S., make sure you have the burner running whenever you add water! Slowly and cautiously add water before it starts boiling. This way the fresh water is boiled ASAP which drives out oxygen and chlorine. If it's left to sit, it attacks the boiler. I say slowly and cautiously because if you go fast it can crack the block.

After adding water, you want the boiler to steam for a good 5 to 10 minutes.

BobC

@chrisj, I'm glad you added the caveat about bringing the boiler up to steam after adding any fresh water.

Bob