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Rusty Pipe at Boiler / Converting Boiler from Oil to Gas


I've got an old (maybe from the '70s) Bryant gas-fired steam boiler and one of the drain pipes off the side seems to have been rusting for a while.  We've been in the house for about a year and certainly this should have been addressed over the summer, but here we are.

The pipe is weeping just a little...not enough to get the basement floor wet, but enough to dampen the insulation and cause the sheetmetal on the side to rust and it appears to have been doing this for years.

I'd like to get this drain pipe replaced before we get to winter, and I've seem mention on this site about the technique where one cuts off the pipe leaving about 1/4", then sawing axially to segment it up and remove it.  I'd most likely bring in a plumber with steam experience to do this (we are in the Metro West Boston area).

Any pointers, besides incantations and such?  I may use a cutoff wheel to open up the sheetmetal around the pipe (without harming the cast iron) such that I can assess the junction of the pipe to the boiler iron itself.  Is this a bad idea?

This leads me to my second question:

Assuming everything goes very bad and I have to replace the boiler, I have noticed that the local Craigslist site is full of oil-fired steam boilers in our size (200k BTU if memory serves) because many folks are converting to gas.

How hard/expensive is it to convert an oil-fired boiler of recent vintage to gas?  I know we don't discuss pricing here, but these boilers seem maybe a conversion makes sense?

I welcome your feedback.




  • Removing a rusty nipple

    You should be able to remove the side panel and get an inch or so to the surface of the cast iron. Drain the boiler first. Cut the pipe a quarter inch from the surface of the section, and as you said, make some axial cuts in the pipe, on its upper side. The trick here is to cut as close to the female threads as possible, but not into them. When you have made several cuts, the the axial strips can be hammered with a chisel down towards the pipe center. You may have to cut, strike, cut again until the old pipe folds into itself, and is easy to twist out. A pipe tap can be used to clean up the threads before putting in the new nipple, and full port ball valve. A hand saw will enable you to feel if you start gouging into the cast iron.

    As regards used boilers, they could be a gamble, and with the cost of a conversion burner, may cost as much as a new one from
  • a3invertera3inverter Member Posts: 64
    Rusty Pipe at Boiler / Converting Boiler from Oil to Gas

    Thanks NBC - the reference to the axial cutting was from something you had written in the past.  Any reason why you wouldn't continue the axial cutting around the entire circumference of the pipe instead of limited to the top half?  Just a consideration of the time required?  I don't want to stress the cast iron any more than I have to.
  • ALIGAALIGA Member Posts: 194
    as for buying a boiler from craigslist

    please calculate the edrs of your current system, i suspect you can probably get away with a smaller btu boiler
  • JeffMJeffM Member Posts: 159
    Cutting out old nipple

    You don't normally need to cut slices all the way around the old pipe and remove it in pieces. Usually once you remove a section or two then some hammering or squeezing of the remaining pipe will get it to collapse inward (now that there isn't material all the way around) and it can be twisted out in a final big piece.
  • a3invertera3inverter Member Posts: 64

    I calculated the EDR as 748.65 sq ft.

    Multiply by 240 to get roughly 180k BTUs

    Assuming an 80% efficient boiler I get 220k Input BTUs

    Which is about the size of my current boiler....
  • saikosissaikosis Member Posts: 57
    I'm Selling an Oil-Fired Boiler in Massachusetts

    Hi, a3inverted. I'm at the southern end of Metro West, converting from oil to gas, and have a Utica oil-fired boiler on Craigslist right now. It's rated for 531 square feet, so it's a bit smaller than you need. The reason I bring this up is because I've gotten mixed answers from contractors about converting it. Some say "no problem" and will stick a gas gun in there for you no questions asked (literally no questions, not even "what model is the boiler?"). Others say they won't do it because Utica says it's not supported. Some said it wasn't safe, others just said they wouldn't go against the manufacturer. After a few guys said they wouldn't do it, I got nervous about whether it was safe and whether the guys who would convert it were reputable, so I'm going with a new gas boiler.
  • SteamheadSteamhead Member Posts: 11,378
    We convert oil boilers to gas all the time

    and have never been accused of being less than reputable for doing so.......
    All Steamed Up, Inc.
    "Reducing our country's energy consumption, one system at a time"
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Baltimore, MD (USA) and consulting anywhere.
  • saikosissaikosis Member Posts: 57
    Not Accusing

    I'm not accusing anyone. I said I got nervous because I heard everything from "they're all the same" to "it's not safe." A lot of this happened before I found this site, so I had no idea what to believe. One guy gave me a price for a conversion over the phone without ever seeing my system and without even asking who made the boiler. Another guy, who did actually come out and look at my system, gave me quotes for converting and for installing a new boiler. Two guys said no because the manufacturer said no. One guy (who is listed here) said no because it wasn't safe.

    Like I said, I didn't know who was right. They're all licensed professionals and they're all saying different things. After I learned some more, I figured out that my current boiler is oversized and it's piped wrong, which made the idea of keeping it less attractive anyway regardless of whether it was safe. I figured I would be better off paying more to get the right size boiler and to get it piped correctly. I also avoid the question of whether a conversion is safe, so that's nice too.
  • a3invertera3inverter Member Posts: 64
    Bringing this full circle...

    I had a pro come out yesterday to address the rusty nipple and its peer on the other side of the boiler as it was starting to look a bit suspect.

    Lots of horror stories from the pro about what could go wrong (which I expected and understood). He favored the approach of just putting wrench to nipple vs the cut it off and section method.

    In the end, both nipples broke off at the first sign of pressure. A bit of tapping with a screwdriver to get the rusty steel bits out and some touching up with brass brush revealed some nice gleaming threads.
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