Corrosion

[Dwm1974]

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

 

[jebatty]

Doesn't answer your question but might the rust be caused by evaporation and then condensation of the water in the tank? If so, it seems likely that the glycol and other chemicals do not similarly evaporate and condense, which leaves only water on the metal surfaces to corrode the steel as water and air mix at the top of the tank.

 

[maple1]

Can you extend your fill tube, or add on a small chamber to the top of it for some expansion room, and raise your fill level so the glycol level is above the top of the tank?

Have you asked CB about it?

 

[BoilerMan]

Can you extend your fill tube, or add on a small chamber to the top of it for some expansion room, and raise your fill level so the glycol level is above the top of the tank?

Have you asked CB about it?

My thoughts exactly. This is the semi-open setup that Europeans use in many cases.

TS

 

[The Weimar]

Can you extend your fill tube, or add on a small chamber to the top of it for some expansion room, and raise your fill level so the glycol level is above the top of the tank?

Have you asked CB about it?

Very interested in hearing the response to this question....

 

[Dwm1974]

I haven't asked CB about it, I guess I should send them an email.
It doesn't seem right that I should have to add a small chamber on the top of the fill tank to prevent this. There are lots of these boilers out there, and I can't seem to find anything on anybody else having this issue. I can't be the only one?

 

[Dwm1974]

Even if I did extend the filler tube and put a chamber for expansion on the top of it, I am not sure if the filler pipe is even with the top of the tank or if it extends into the tank even a little bit. If it does then there will be an air space at the top of the tank reguardless of how much I top it up.

 

[Heat1285]

make sure your water level is full and make sure you are running hott....centrals should all be ran about 175-185 or even 180-185. This will allow minimal expansion and contraction. My Heatmor has a bladder on it that holds 8 gallons for this exact reason.....

 

[maple1]

Even if I did extend the filler tube and put a chamber for expansion on the top of it, I am not sure if the filler pipe is even with the top of the tank or if it extends into the tank even a little bit. If it does then there will be an air space at the top of the tank reguardless of how much I top it up.

I haven't even seen one of these in person - but am thinking that if the filler pipe extended into the tank, you wouldn't be able to top it to fill level since there would always be a bubble space up there.

There are people out there who have had issues with OWBs rusting out prematurely - maybe this little detail is a contributor. I am thinking most people might not be watching as close as you and not noticing what's going on up there.

 

[Heat1285]

its depends on the manufacturer. There are some brands like Shaver that are horrible.....we have cut one open just to see the design and i think my 10 year old son could have designed them better......then there are other brands like Heatmor and Heatmaster that have perfected the 409 SS stove. bladder systems, double bypass...the whole 9 yards. My neighbor has a heatmor that is going on 15 yrs with zero issues....keep it full of water and burn hot and it should last you a long time...biggest things that kill these stoves are dumb dealers who dont know what they are selling and dumb owners who learned from the dumb dealers...LOL...running at low temperatures and running with low water will kill these things....also keep a small differential between the fan on and fan off temps.... extreme expansion and contraction on anything metal will cause damage. I run mine at 175-185 in mild weather and 180-185 during the cold season.

 

[Dwm1974]

I run mine at 170 - 180, unless it gets really cold, then I bump it up to 185. I am in northern ontario so it gets quite cold here in the winter. And I always make sure the glycol level is slightly above the full mark. I'm thinking this weekend maybe I will bump the temp up to 190, then top off the glycol right to the bottom of the filler pipe, maybe a tad more, then set it back down to 180. Any thoughts?