Holes in the top of my steam boiler

Jharrin

My 10 year old steam boiler has holes in the top of the cast iron. I have seen
this before in several boilers. Always the same manufacturer. I understand
It to be from carbonic acid. What causes it, what can be done about it. 10 years
Isn't very long for a boiler to last. Thanks for any help.

nicholas bonham-carter

Over-pressure, and lack of main venting can cause an increase in co2 being dissolved in the condensate, resulting in higher concentrations of carbolic acid.
There could be another cause, however-could there be higher levels of chlorides in your tap water, from the main water supply? Is there anything stored near the boiler, containing chlorides, such as water-softener salt, or softened water feeding the boiler. Look up graphitic corrosion here for further information, as when you replace the boiler, you want more than 10 years out of the new one!--NBC

Steve_210

Freshwater in my opinion is probably the culprit
Make up water should be metered so you can see how much water you were using

SwedishPimple

Bummer about your boiler. I hope you figure this out.

This discussion makes me wonder if some sort of sacrificial anode rod technology could be deployed to prevent this type of failure?

Do they make such an animal for residential steam?

S.P.

ChrisJ

I would not say it's always the same manufacturer. They all pretty much suffer from it.

What can you do to prolong the life of a steam boiler?

Always boil fresh water as soon as you add it. Personally, when I know I need to add water I wait until the thermostat fires the burners up, When I hear that I go down and slowly add water. This way it's boiled as soon as possible.

Repair leaks and limit the amount of water your system uses. The less fresh water added the better.

Check your PH! This is something most people don't seem to do and it's the most destructive. In my opinion you want your PH between 8 and 10 though some say 7 is acceptable.

Use a product like Rectorseal Steamaster tablets to reduce corrosion. These also increase your PH and turn the water purple allowing you to roughly judge the dosage. Do not follow the instructions on the bottle as it's wrong. Use 1 or 2 tablets and monitor PH. Romar also makes an excellent product for this but I have not personally used it yet but hope to try it in the future.

The most important thing when using water treatment is not using too much and making sure your boiler water is absolutely oil free.

Jharrin

Thanks for the help everyone. I appreciate all of it.

davidnyc

I notice that everyone mentions Rectorseal Steamaster tablets and not their 8-way liquid, which is more convenient to add. Any particular reason? Any problem with 8-Way? According to MDS, it's Sodium Nitrite, Sodium Hydroxide and Sodium Phosphate.

ChrisJ

davidnyc said:

I notice that everyone mentions Rectorseal Steamaster tablets and not their 8-way liquid, which is more convenient to add. Any particular reason? Any problem with 8-Way? According to MDS, it's Sodium Nitrite, Sodium Hydroxide and Sodium Phosphate.

No reason really other then I've tried to contact Rectorseal twice and was completely ignored so I don't know what the differences are.

Larry_52

Steve said:

Freshwater in my opinion is probably the culprit
Make up water should be metered so you can see how much water you were using

x2 agreed. CO2 is in the makeup and after cycling will wind up in condensate and boiler return as carbonic acid. you could use a slaked lime with soda ash or just plain caustic as treatment. this will remove hardness and eliminate the carbonic acid. I tend to use straight caustic. Above a pH of 8.2 with NaOH caustic added all co2 is converted over to sodium carbonate (harmless) before you even heat the water. Just keep the boiler above 8.5 pH with one of the above . I recommend a glass type pH meter that is maintained properly for the checking of your water.