Does underwater near-boiler piping act as a sacrificial anode for a steam boiler?

ethicalpaul

I woke up with a possibly dumb question this morning. The summary is: if copper is used for near-boiler underwater piping in and around the Hartford Loop, might that cause more corrosion in the boiler?

The poll is anonymous so you can tell me what you really think 😅

I'm not thinking about due to electrolytic effects, I'm thinking because we remove metal that could take some corrosion on itself instead of the boiler, kind of like a sacrificial anode.

Here's a 3 minute video that explains what I was wondering:

https://youtu.be/VHfM9bFysZ0

Wcurtis

Why couldnt a sacrificial anode be installed in the return line, seems like it could work,

https://a.co/d/apGTHoq

other than obstructing return flow and accessibility and neither appear to be a real problem

ethicalpaul

yeah that one’s not sacrificial, it’s powered. I just installed that exact one in my heat pump water heater and have considered one for my boiler, but I’ll be dead before my boiler so the ROI is…questionable 😅

My Peerless has lots of ports in it so I could use one directly into the boiler

EBEBRATT-Ed

@ethicalpaul

Just keep at it and you will put the boiler manufacturers and most of the contractors out of business!!!!!

KNOCK IT OFF!!!!!! LOL😉😉😉😉😉

Wcurtis

Direct fit into the Peerless does seem better and not being electrical has benefit.

In the powerplant world where I come from we use simulators to test various theories, if a test unit could be built simulating returning water conditions it may be worth considering if truely board and need a project

Just placing into the boiler and checking over time would be less aggrevation.

Wcurtis

We use a water box condenser in cooling towers with both end bells having sacrificial anodes however the cooling tower water is no where as clean (high conductivity, neutral PH and sometimes high calcium depending on removal method) as returning condensate from the boiler BUT if a test port could be used while maintaining your current boiler chemistry parameters, I THINK this could be a great test if the PH is kept high and conductivity low….all this makes me also wonder if an oxygen scavenger would be beneficial in a low pressure boiler if the oxygen content of fresh water addition is a concern……sorry I got off on a tangent.

Larry Weingarten

Hi, Sacrificial (or powered) anodes are pretty much line of sight… Think fluorescent tube and what directly sees the light… Copper plumbing could put bits of copper into the boiler, which could cause pitting. The cast iron boiler, and steel piping are very near each other on the galvanic scale, so I don't imagine any serious interaction between them. 🤔

Yours, Larry

dopey27177

I been in this business for forty years both as an installer, repair tech and consultant. I have seen buildings with underground wet returns last for more than 20 years, buildings with above ground wet returns in them for as long as 50 years and of course dry returns in some buildings for 75 years.

If you look at the real old buildings you find that the fittings were cast iron and no corrosion occurred where brass or copper was installed into the cast iron fittings.

Today many jobs are done with steel fittings, even there it is rare that for the brass or copper fittings will corrode to point that a leak will occur in 20 years.

Every thing depends on how much air is in solution with condensate return.

to lessen galvanic action dielectric grease can be used in lieu of pipe compound.

Jake

EdTheHeaterMan

I was almost going to pick the last option just for the fun of it. but I didn't want to be the first one to do it Paul. It is an interesting concept. I just want you to know that @Jamie Hall , who takes care of Cedric, has more experience with that system and can better answer your query. My vote was “probably but it doesn't matter”  because I have replaced 80 year old steam boilers that were working up till the day I removed them. So 80 years of rotting pipe can make the boiler last a little longer.   There was a rotten wet return buried in sand on one of those old boilers and when I replaced the new boiler I discovered that the wet return had rotted away because the water feed had a meter on it and it reached 999 gallons within 6 weeks of operation.

I knew that was not good. I needed to crawl through the entire foundation of two very large buildings until I found this TINY LITTLE crawl space under the pastor's office. That was an “afterthought” addition that connected the two buildings over 50 years ago. The dry return vanished into the sand as soon as it exited a foundation wall of one building. Then it emerged in the basement of the other building where the condensation from 3 different mains connected and went off to three different parts of the campus.

While looking at the sand on this tight crawl space I couldn't help but notice that the subfloor of the pastor's office was pressure treated tongue and groove boards. Then it hit me! There was a rotted floor in the pastor's office some years ago. It must have rotted away as a result of excess moisture coming up from the sandy floor of the crawlspace. Of course, being a church, some parishioners volunteered to repair the floor and all was good for a few years, until the floor rotted away again. So the volunteers decided that the only way to fix that is to use pressure treated lumber. That stuff won't rot away so fast.  

That buried return must have been leaking for years, and when I dug it up, less than two thirds of the pipe was left.  The bottom third was completely gone.  So a combination of steam and hot water from the dry return was finding its way through the sand and forming water droplets on the bottom of the floorboards for a number of years.  Replaced the pipe and the replacement boiler only uses about 10 gallons of water per year now.     And at least 8 of those gallons are from flushing the LWCO each week.  

Fuel bill was much lower after the return was replaced, but I let them believe it was the new boiler that caused all that savings.