Rust in one pipe system

PhilKulkarni · May 21

I am draining about a quart of water every two weeks from my 3 yr old boiler due to a high amount of rusty water and rust particles The problem predates the boiler but was less severe and I have been using 8-way for the past 2 yrs to control the rust. Last time The boiler accumulated so much rust was when the wet returns were so corroded that I was able to push a pencil through one of them. I replaced them, but since that was 23 yrs ago, I checked them again by tapping them with a hammer and they are solid.

Which other pipes should I check next? The pipes are insulated throughout. Should the dry return- the 1.25” dia section after the last riser that drops into the wet return, be the next pipe to check? It is about 28’ long and in a crawl space where it is a bit difficult to maneuver. Curious how long a typical dry return(black pipe) lasts, considering that the condensate from all the risers on that loop traverses it. My dry returns are going on probably 50+ yrs. Also since I have partially counterflow headers, some of the rust is also coming from the drips installed on them and if they are the primary source of the rust then I will try to adjust the PH a notch higher.

Thanks for your help.

EBEBRATT-Ed · May 21

Any pipe above the boiler water line usually lasts forever. It's just the pipe below the water line that causes issues.

mattmia2 · May 22

Unless there are system issues causing the boiler to throw water up in to the mains the rust through is usually only in the parts below the water line. Adding some valves and tees to flush the wet returns once a year is a great idea. Some tees and valves or plugs that let you wand and flush the boiler once a year help too.

Big Ed_4 · May 22

Do you keep up on repairing any steam leaks ? With steam leaks the water will escape out of the system and leave the minerals (solids) behind . Hi iron water would leave a redish color mud in the boiler .

dabrakeman · May 22

If you have a sag in a return it can rust there.

ethicalpaul · May 22

Stop the regular draining. You are introducing oxygen with all that fresh water. Put in enough 8-way to increase the pH to 9 or 10 and let it be

PhilKulkarni · May 22

Thanks for the feedback everyone. At the beginning of each season I drain just enough water from the boiler and the wet returns until it runs clear. But this is not preventing rust particles from gumming up my rad vents. As far as I can tell, open rad. vents are the primary sources of steam leaks in my system and I discover them about a month or so into the heating season when the boiler runs for longer periods. Most of the time cleaning out the vent with tap water works, other times I have to replace them if they still don’t close. This has become a chore.

I am not aware of any other leaks but they could be masked because I am draining and adding water due the the rust issue. Next season, I will check the water level after a month of use without drawing down the the rusty water to determine if there are steam or water leaks that might be contributing to the rust.

As for the 8-Way, I have been adding it in small amounts until I notice a slight reddening of the water. Not too scientific I admit. I will check the PH level with color strips.

Grallert · May 22

It seems to me you have other issues. Your vents shouldn't be seeing anything that would blow up you vents.

Are you making a very wet steam?

mattmia2 · May 22

https://forum.heatinghelp.com/discussion/comment/1856130#Comment_1856130

Are the main vents adequate and working?

Jamie Hall · May 22

And I don't think it has been asked — but what pressure is your system running at?

PhilKulkarni · May 22

Hope I can address all the questions:

Wet steam?

Possibly. When the steam reaches the vents, I notice they gurgle before shutting off which is more noticeable at night. There are no water droplets though, and because the Ventrites make a clicking sound when they close, I can see that they are not leaking steam after they close. Other factors- The header ht is 34” above the water line which drops 2-2.5” while the boiler is steaming. The boiler takeoff is 3” while the header is 2”.

Clogged vents?

I am attaching a pic of the rust particles from the boiler. These are very large compared to the ones that clog the vents. The vents have a small amount of water which does not seem to interfere with their operation

Boiler pressure?

During most of the heating cycle 30-40 mins, depending on ambient it is 0 psi on a 5PSI gauge. When the outside temp is in the 20s the pressure will climb to 0.5PSI but the boiler shuts off on temp. When the temp drops into the teens, the boiler cuts off at 1.8PSI and will cycle once and shutoff in 5 mins. on temp.

IMG_0629.jpeg

Thanks.

Grallert · 1:20PM

I guess depending on the size of your boiler that seems like a big drop in water level.

ethicalpaul · 1:38PM

Yeah, I agree it's more than I'd want to see. I'd want to see 1" to 1.5" or so

It can be hard to determine if you are carrying over water from the boiler into the mains and beyond (if you don't have a sight glass on your riser).

In normal operation, only steam would get into your main and there would be no issue with rust particles getting carried from your boiler to your vents. Rust should make its way to the boiler carried by condensate, a one-way trip.

Was your boiler skimmed when it was installed?

PhilKulkarni · 3:06PM

More information:

The main vents(Big Mouths) on each of the two mains has been working fine since I installed new O rings. As an aside, they don’t open as quickly as the rad vents while cooling down so the system sucks in air through two rad vents that open at nearly the same time. This does not bother me as much as the rust formation which is a bigger issue.

The water level drops much less after the rusty water is drained and replaced, and the steam is also ‘dryer’ but this lasts for around 2 weeks as the rust build up increases. You could say that watching the water level drop by more than a third of its ht is a proxy for alerting me to the rust build up.

While the Ventrites stay open when clogged with rust particles the #4 MOMs instead stay closed leaving the affected rad ice cold.

The boiler has been skimmed 3 times in the year of the installation and once again after the drips were installed. I made sure all the cutting oil the from the drip pipes was removed prior to installation making the skimming easier.

Thanks.

ethicalpaul · 3:59PM

If you have a reasonable amount of 8-way in your water, rust just should hardly be forming at all. Something is up.

Here's my boiler after a year of no draining at all. My pH was around 10 but you don't need it that high to dramatically reduce corrosion

https://youtu.be/Bx8NryCUkng

Grallert · 4:05PM

From your description it sounds like you've done everything right. The fact is there should be no rust in your supplies or radiators. How's the water getting in? I can't imagine that the vacuum created by the slow BM vent is causing enough humidity to enter the rad vent to cause the trouble you're having. With out seeing the system I've got nothing.

PhilKulkarni · 9:46PM

Thanks ethicalpaul, that is an impressive feat. Here is what my rusty water looks like after 1.75hrs of operation yesterday.

IMG_0631.jpeg

I think most of this crud is coming from my pipes and not the boiler. I have no definitive way to prove it but since my boiler is ending it’s 3rd season and I have been adding 8-Way, the latter is only inhibiting rust in the boiler but not the pipes. However, if the pipes above the waterline last indefinitely, then my only option is to tear out the insulation on the entire wet return and check the condition.

My other suspicion is that the rust buildup is throwing up water into the mains and creating wet steam which is why I find water in the vents when I go to rid them of rust particles. While this water is not oily, the smaller rust particles get suspended in the boiler water which eventually get suspended in the wet steam and travel to the the vents. These particles are not large enough to clog the BMs.

I will drain my boiler and put distilled water + the 8-Way and see if that helps.

Thanks.

mattmia2 · 10:40PM

ut vavles on your wet returns so you can flush them with a hose. the additive will mix in to the returns but there isn't enough flow with just the condensate to flush 100 years of rust out of the returns but some of it will come back to the boiler. if that rust is ending up in the mains it is surging or priming some.

Rust in one pipe system

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