That Pesky O₂ Molecule – How Oxygen Finds Its Way Back Into a Steam Boiler

An observation about where oxygen does its real damage:

You are right that oxygen enters cold water and we do of course see returns (usually at the boiler) rot out pretty quick.

However, where do the boilers always fail? At the top of the section, every single time. How is that possible? There's no water up there, there's only air and steam, right?

You also said in your video correctly that the oxygen is forced out of the water as the water is heated. But I would ask "where does that oxygen go?" It is released into the steam chest, or the upper part of each section, where it is free to attack the cast iron. This is why I think it doesn't matter when you heat the water you add to the boiler—regardless that oxygen is going to be freed to attack the boiler.

So in my mind, the best way to keep your boiler from seeing premature rotting death is to use makeup water that was recently boiled, and to use a product such as 8-Way that has oxygen scavenging capability as well as the known corrosion-reducing pH booster chemicals.

Thank you for your video!

you have it very easy. Your Utica has these side outlets to which you can attach an elbow and a nipple sloped toward the boiler with an optional reducer and ball valve

With this setup you can add treatment or even all your makeup water (I add only heated distilled water because I’m a fanatic)

I don’t recommend a separate water heater setup because it’s too easy to just pour it in yourself every few weeks (minimizing leaks is the first priority)

PS I see from your contractor’s sticker you are in Michigan. Hello from a native Michigander

Could we consider rot above the water line as a victim of O2? 

Absolutely

What are folks view on a small carbon block filter on the feed water to remove chlorine and light solids… not worth the bother, no point?

Ezzy and Clammy do it. I exclusively use pre-heated distilled water for makeup water, so I'm not one to judge

Yes I have noticed the same thing from a distance of this forum @STEAM DOCTOR that all holes seem to always be at the top of the sections.

And yet the other major rot point always seems to be where the wet return hits the boiler, so something interesting happens there as well.

@Day_Tripper that is a lot more water than I like to see being added. Look for leaks of steam or water, especially the vents. There is also the possibility that your boiler has a hole in it as seen in the above picture (but probably smaller). I want to see less than 1" of drop in the gauge glass every month or so during the heating season. Using as much water as you are using will reduce the lifespan of your boiler. Of course if it already has a hole in it that concern is in the past.

Is your main concern with an external heater/bubbler that the potential for leaks increases with more connections?

No, just that it's a lot of hassle for minimal benefit

You are in a difficult situation with that removed radiation.

But you are exacerbating it with that 5 degree setback at night. I recommend stop doing that and see if the downstairs is able to stay comfortable.

If the upstairs gets too hot for your comfort at night, try covering one or more radiators with blankets until you are comfortable, but keep in mind doing so is similar to removing radiation and may make your system cycle more.

Cycling more isn't a big deal for gas, but could be more problematic for oil.

Can you send a photo of this "rust separator"? You might be referring to a float-style low-water cutoff device

Do you think that Rectorseal 8-way can protect steam mains at all? They say it does but I'm skeptical unless there is a lot of carryover. Otherwise it should be distilled water I believe. Here's what 100 years of corrosion inside a steam main that is not pitched correctly looks like. This is the downstream end of a 16 ft. section that went into a Tee for the riser to an upstairs radiator and what it looked like after I cut through it and chiseled it out. Kept it as a souvenir. Even if it is basically distilled water I would think that it would absorb CO2 from the air in the main and create some carbonic acid. But it is obviously very hot and would limit absorption. In the off season I had cool distilled water pooled up in there and saturated with air containing CO2. Would be interesting to know what the pH was. Anyway, you can see that this main rotted out at and below the waterline and there is lots of meat still on the pipe in the upper areas.

For comparison, here is the upstream end of that 16 ft. main that did have a small amount of downward pitch (unlike being level at the other end), and 1/2 in. higher elevation. Much less corrosion and presumably no standing water situation.

I have the last radiator on a first floor run that blasts water out of the radiator vent. It has it's own wet return pipe to the main wet return. We have double checked everything for the cause. I have to add a small amount of water to the boiler once a week. For the summer I over fill the boiler with plenty of extra water and Steam Clean is used as a deterrent all of the time.

Any ideas ? Thanks.

"Carryover is occurring ? " What is that ?

Sorry for the late reply. The sight glass will drop about 2" during a heat cycle.

I'm a little bit late to the party but I'd say that weekly blowdowns (assuming you have a float type LWCO) are not required under one circumstance. If your boiler is in good operating condition and your float type LWCO has been cleaned and verified to be fully functional and maintained….than RectorSeal 8-way to the rescue!

I was doing weekly blowdowns to get the rusty, muddy sludge out of my LWCO in my ~45 year old Peerless. I took it apart, cleaned it, and put new gaskets on the LWCO and started using RectorSeal 8-way at 1oz/gallon probably 7+ years ago. My pH is about 10.5 and absolutely no more mud/gunk/rust build up inside my boiler. My LWCO water would drain perfectly clear (well, slightly purple) even after weeks/months of not doing a blowdown.

I do it once a month…ish now. Comes out clean every time. This heating season I have added water twice (manual fill only). Each time it was about an inch of water on the site glass.