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Corrosion

Started by dwm, November 24, 2015, 09:01:09 PM

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dwm

Hi Everyone.
I have a central boiler cl5036 that was installed in the fall of 2011 to replace an older wood boiler (cant remember what it was) where the top of the tank had rusted off of it. I am running glycol in the system with rust inhibitors and regularly test the glycol for ph (it is between 8 and 9) and nitrite levels. I have added 1 gallon of molydbate (as recommended by my local plumbing supplier) and have added a small amount of central boiler rust inhibitor to keep the nitrite levels up. I have even taken a glycol sample in a glass jar, added a piece of steel wool and left it to see if any rust forms on the steel wool (which it doesn't). I am confident that my actions are keeping corrosion away below the top of the glycol level in the furnace.
The other day I looked down the fill tube on the top of the boiler with a flashlight and noticed there was a bit of corrosion on the inside of the fill tube. This leads me to believe that there is probably corrosion also on the top of the inside of the tank ABOVE the glycol level. Now I am worried that I will end up with the same problem as the old wood boiler where the top of the tank rusts away to nothing. Is there anything that can be done to prevent this? My glycol level is just slightly above the full mark. When I look down the fill tube the glycol level is a couple inches below the fill tube so obviously there is an air space at the top of the tank. What can I do to stop any rust??
Thanks!
Dean

Holmes

Because it's an open system the water will always absorb some oxygen. Is the fill tube a sight glass?  Sight glass tend to collect rust on them.. It sounds like you are taking good care of your system.
Think like a farmer.

dwm

No, the sight glass on the front of the boiler is nice and clear.  I'm talking about the main fill tube on the top of the boiler.  It is metal and runs through the roof of the boiler down into the water jacket.  When I shine a flashlight down and take a look there is some light surface corrosion starting.  Was hopefull that I could find a solution to stop the rust as the boiler that was here when I bought the house rusted out at the top of the water jacket.


Gearbox

With a piece of radiator hose and a smal expansion tank with a open vent- fill you could fill the boiler full and expand into the tank above . if the small tank rust's just replace it .  I couldn't tell you how big to make the tank . Someone here will know how much water expands . gearbox
A bunch of chainsaws a BT6870 processer , TC 5 International track skidder and not near enough time

jgoodhart

just fill the boiler up into the fill tube so the treated water is in contact with the metal. Make sure it is vented when you cool the boiler down and reheat it, it should always be vented anyways but I have had problems when the vent didn't work as it should.

Logging logginglogging

Quote from: Gearbox on November 25, 2015, 09:17:01 PM
With a piece of radiator hose and a smal expansion tank with a open vent- fill you could fill the boiler full and expand into the tank above . if the small tank rust's just replace it .  I couldn't tell you how big to make the tank . Someone here will know how much water expands . gearbox


I was thinking of doing the same thing..
However currently, I have simply filled all the way to the top of the fill tube, its vents so its ni big deal when the water expands and runs out the top a little.

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