Clogged Steam System Repair

One of the common steam heating service calls we get dispatched to are steam heating systems that are not working properly. Homes in northeast United States typically have an oil or gas fired boiler – either hot water hydronic or steam and Pipe Doctor Plumbing, Heating, Air Conditioning (and now) Refrigeration technicians often get called last (when other plumbing contractors have failed) to tackle the job. As a company that specializes in service and repair, we have a great deal of knowledge, experience and expertise working on these types of systems. The job recently competed as detailed in the rest of the article is no different.

Last Friday we were called upon another frustrated homeowner in Valley Stream who was tired of “amateurs” attempting to fix their gas fired Weil McLain steam boiler. The first plumber replaced the steam radiator air valve what continuously sprayed water into the room. They essentially “masked the effect” but didn’t resolve the “cause” of the problem (since the new air valve sprayed out water a few hours later). Plumber #2 closed the radiator valve and said the radiator was clogged. The next day the main air valve at the end of the steam main in the finished basement flooded the basement with gallons of water – and took down a large section of drywall ceiling in the process. Plumber #2 returned the following day and said the boiler was flooded. Drained the boiler and, yup you guessed it, the issue returned later that evening.

Any good technician asks questions and listens. A homeowner can usually give the tech a wealth of information. Because that’s what we are trained to do. Listen. Diagnose. Resolve. There is no guessing. (I’m not saying we get it right 100% but we do resolve 100% of our clients issues).

In this example the issue was obvious. On this steam system the rear wet return was clogged. Just like a clogged shower or sewer main it prevented condensate (water) from returning back to the boiler. With nowhere to go it sat at the end of the wet return slowly filling up the drop from the end of the steam main and as steam, rushing from the boiler at 40+ mph, forced the water out. Anywhere it could. It went out of the steam radiator air valve and the steam main valve. At the same time the water was violently exploding (since it was expanding 17,000 times) as that steam hit it causing severe water hammer. No Mr. & Mrs. Homeowner, your home is not possessed by demons. (We had an elderly couple the previous week who really thought that)

The solution unfortunately wasn’t so simple in this completely finished basement. With the exception of the boiler room, none of the piping was visible.

Here are the steps we took:

  • (1)Using our Flir i7 thermal imaging camera we traced out all the steam main piping and wet return drops.
  • (2) We carefully opened walls and ceilings to expose piping we needed to access (cleaning up all debris in the process).
  • (3) 80 year old steam piping isn’t easy to take apart, but with experience comes know how. We cut and disassembled piping to cut in new isolation valves and drains on both wet return drops.
  • (4) We cut and disassembled the wet return immediately before the Hartford Loop to install another set of isolation and drain valves.
  • (5) Carefully using pressure regulated domestic water (with a check valve) from the water heater drain valve we flushed out each wet return removing tons of debris. Kind of like low pressure water jetting, until the return piping was clear and clean.
  • (6) We flushed and drained the boiler multiple times. Also removing nasty debris that can interfere with heat transfer, clog up the pigtail, fowl up the low water cut off, etc. And finished up with treating the boiler with steam boiler chemicals.
  • (7) No job is complete without a combustion and draft analysis, usually done after cleaning out the main burners and combustion chamber. Printed the results, with date and time, and attached a copy to the front cover of the boiler.

End result? Another completely satisfied homeowner with a quiet system. We advise all homeowners to have their heating systems inspected, tested and cleaned annually by a reputable, experienced and knowledgeable plumbing and mechanical contractor. Steam boilers should be flushed out monthly during the heating season and the wet return should be flushed out annually. See our other articles for information on how and why this is very important on steam systems.

If you are within our service area we’d welcome the opportunity to service your property. Give us a call at 516-348-6300 or email us at If you are outside our area check out HERE and HERE for a referral to contractor who can help!

Disclaimer: This article is for informational purposes only. Do not attempt to tackle a job like this yourself unless you are a skilled and experienced plumber. Under no circumstances attempt this on a weekend, late in the evening or on a major holiday. You can become royally screwed and end up without heat. Yup, your wife will yell and likely divorce you! (Especially after the plumber visits and gives you the bill!) Just Kidding! Laugh now then check out our YouTube channel. While your at it, visit us on Facebook and ‘like’ our page. Thanks for reading.


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D. Summers

My water heater stop working and I needed a replacement. I Called pipe doctor and within 3 hrs Mike showed up, looked at it, and gave me a reasonable price. Mike was very professional and did a great job. Keep up the great work!!!

Parrish Family

While we live several states away, we watch the videos that Pipe Doctor releases on Youtube. Mikey is extremely responsive on their social media platforms, even to people that are not their direct customers. If Pipe Doctor ever branches out to my area, we will absolutely use them for all our HVAC and plumbing needs.

J. Miller

Mike and his crew are fantastic. Aside from exceptional work which is evident if you watch any of the YouTube clips, Mike’s knowledge is out of this world. Not only does he know his stuff, he also spent the time to make sure I had a solid background of the inner workings of the system. That’s very helpful to a homeowner!

J. King

Daniel and Mike did a great job repairing my Navien. They were here right away and fixed the issue I was having. I would highly recommend Pipe Doctor!

J. Pearl

Had the original boiler in our house finally go. Within 24 hours mike was here to put a brand new boiler in and we are warm again. Would definitely use pipe doctor again!

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I have been following Mikey Pipes/ Pipe Doctor on his YouTube channel and having watched all of his videos I must say that he is one of the most honest contractors I have ever seen and his professionalism is incredible. It is so impressive that he always gets to the root of the problem quickly and always comes up with the very best solution on the spot. Anyone that hires his services must consider themselves lucky!

M. De La Torre

Mike and his crew replaced my waste pipes. They took their time and did a great job making sure there were no leaks and cleaned up after they were done. Will continue to use them for other projects.

R. Philip

Pipe Doctor is definitely an A++ local business that is amazingly professional, more than reasonable in pricing, and super super fast. They do not skimp in on using the best product and the services that they provide is second to none. They finished my water heater install same day in the snow within 2 hrs from call, negotiating, delivery and removal. Will use in the future without a doubt. Pipe Doctor second to none!

T. Van Buskrik

This is my second year using Pipe Doctor for my HVAC maintenance. Mike and his technicians are simply the best in the business. They arrive on time, are courteous, and most importantly they know their stuff. They do the job right.

S. Gordon

Pipe Doctor is such a pleasure to work with the customer service department is so efficient. The plumbers were on time and a pleasure to work with. Mike G is a real professional not only is he meticulous in his work, he cleans up and makes the place look cleaner than when he would started. Would highly recommend their service.

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