by Patrick Linhardt

The Phone Call
It was strange for summer. A service manager was concerned about repeated automatic water feeder failure on the steam boiler at the home of one of his good customers.

These calls usually come into my office at the supply house in the milder parts of the heating season, not during the cooling season.

However, when the same component is replaced repeatedly under warranty, I get a little nervous and curious. We agreed to look at the system together.

I recognized the corner address he gave me. I'd never been inside, but had often driven past and admired its stone walls, porches, and turrets.

Since I'm considered by some to be a steam geek, I wasn't disappointed by what we found inside: a wonderfully intact vapor system from the 1920s. Sure, the boiler had been replaced a few times, but the radiator supply valves, traps, main air vents, and boiler return trap were all still there.

Together, they controlled the steam flow, air removal, and condensate return in this classic two-pipe system. The geek within me was excited.

The nice elderly couple who lived there for the past 40-plus years told me how much they loved their "old steam heat."

Nevertheless, during this past winter and spring, they had to keep draining the boiler and replacing the feeder. I dutifully followed them to the dining room to look at a radiator and noticed the nickel-plated finish on the 75-yearold supply valve.

The steam inlet was at the top port on the radiator and the trap was at the bottom port on the opposite end, just like it should be on a vapor system. The service manager and I excused ourselves from the couple and headed to the boiler room.

The Troubleshoot
We didn't want to fire up the boiler while the A/C unit was whirring away. I had just published a book on steam heating, and my service manager friend wanted to see my new book in action. Proudly, I unzipped the cover and flopped it on the top of the boiler.

First, we did a quick tour of the basement to familiarize ourselves with the piping.

We found the end of the mains and their vents. Then, back in the boiler room, we checked the book and agreed to use the flow chart "Boiler flooding" to start troubleshooting.

All the usual suspects — dirty boiler, high pressure, and near boiler piping — checked out okay. We zeroed in on determining if the the wet return was clean or clogged. The vapor system used a boiler return trap that has two check valves below it in the wet return. Sure enough, they looked original too.

Now, the wet return is the lowest part of the system and consequently, accumulates the sediment, rust, and junk of operation. This junk loves to build up around any obstructions, such as a check valve.

Since I'm considered by some to be a steam geek, I wasn't disappointed by what we found inside: a wonderfully intact vapor system from the 1920s. Sure, the boiler had been replaced a few times, but the radiator supply valves, traps, main air vents, and boiler return trap were all still there.

These two valves evidently had 75 years to get fouled up, because they didn't have any wrench marks and the original installer didn't provide any cleanouts in the wet return. It was looking less like a feeder problem.

We diagnosed the problem as a clogged or slow wet return, slowing the condensate return and causing the feeder to open. After a few cycles, the boiler would flood with the return of the slow-moving condensate.

The system could be updated and the problem solved by repiping the wet return, this time without the boiler return trap and the check valves. The need for a boiler return trap ceased when the first gas-fired boiler was installed. Its job was taken over by the pressuretrol or vaporstat. Keep that set low enough, and gravity slides the water back into the boiler, as long as the pipe is clear.

The Follow-up
As with other diagnoses of old steam systems, this one was only partially correct. The check valves were found to be clogged but were passing some water. However, a 1-in. wet return traveling 70 ft. from a faraway corner of the basement was found to be 99.44% plugged.

The condensate from that part of the house, maybe 25% of the system, was coming back extremely slowly, causing the feeder to flood the boiler. This wet return was even lower than the checks and consequently got the lion's share of the system buildup.

We gave the owners a review of what we found. The couple understood that it was time to re-pipe the wet return and gave the okay to start. My supply house didn't have to eat another part that wasn't defective and saved some money. The geek in me enjoyed the whole experience.

Patrick Linhardt is the sales manager at Aramac Supply in Cincinnati. His newly released book, Linhardt's Field Guild to Steam Heating, can be ordered at www.steamupairoutwaterback.com or by calling 513/703-5347.