Steam heat is a Pittsburgh signature. Walk through Beechview, Bloomfield, Squirrel Hill, the South Side, Lawrenceville, parts of Shadyside, and the older neighborhoods of Mt. Lebanon, and you will find homes that have been heated by steam for sixty, seventy, ninety years. The system is simple in concept and durable in practice. A boiler in the basement turns water into steam, the steam rises through pipes to cast iron radiators on the upper floors, the steam gives up its heat, condenses back to water, and gravity returns the condensate to the boiler.

A properly maintained steam system is one of the longest-lived heating technologies in residential use. Forty, fifty, even seventy years of service is documented across Allegheny County. The catch is that a lot of Pittsburgh contractors do not know steam anymore. The Wahl team does. Our master plumber and senior installers have done steam boiler replacements across Pittsburgh’s older housing stock for years.

When you need a new steam boiler

Steam boilers fail differently than hot water boilers. The most common reasons for replacement:

• Cracked or leaking boiler section, water in the burner pan
• Repeated low-water cutoff trips that are not fixed by feed water adjustments
• Heat exchanger corrosion (rust flakes in the gauge glass or skim port)
• Combustion chamber failure
• Burner controls failure on an obsolete model with no parts available
• Boiler so oversized that short-cycling is unfixable

Steam boilers often run for decades, but when they go, they go. We carry replacement options for one-pipe and two-pipe steam in the most common Pittsburgh sizes.

One-pipe versus two-pipe steam

This is the first question we ask on any steam job.

One-pipe steam uses a single pipe per radiator. Steam goes up through that pipe, condensate returns through the same pipe by gravity. Each radiator has an air vent (the small valve on the side that hisses when the system fires). One-pipe is more common in residential Pittsburgh stock.

Two-pipe steam uses one pipe for steam supply and a second pipe for condensate return. Each radiator has a steam trap. Two-pipe is more common in larger or more elaborate Pittsburgh homes and small commercial buildings.

The boiler choice, the near-boiler piping, and the controls all depend on which system you have. Get this wrong and the new boiler will not work right no matter how good the equipment is.

What we install

• Cast iron sectional steam boilers (the traditional and best long-term choice for residential steam)
• Power-vented steam boilers where atmospheric venting is not viable
• New near-boiler piping (Hartford loop, equalizer, header, riser configuration matched to the boiler manufacturer’s specs)
• New gauge glass and water column
• New low-water cutoff (probe and float types)
• Automatic feed water systems where appropriate
• New skim port and skim valve
• Steam vents (one-pipe systems)
• Steam traps (two-pipe systems)
• Pressuretrol controls (operating limit) and vaporstat (low-pressure controls for older homes)
• New gas line sizing
• Chimney liner replacement

Near-boiler piping is the part most installers get wrong

Steam boilers are sensitive to how they are piped. The header above the boiler, the equalizer down to the wet return, the Hartford loop, the riser sizing, and the takeoff configuration all matter. A new steam boiler piped wrong will surge, water-hammer, deliver wet steam to the radiators, fail the low-water cutoff, and shorten its own life.

We pipe steam boilers exactly to the manufacturer’s specs. That sometimes means cutting and replacing existing pipe that the previous installer left in place. It is the right way to do the job and we do not skip it.

What goes into a Wahl steam boiler install

1. Survey the existing system, one-pipe or two-pipe, radiator inventory by EDR (equivalent direct radiation)
2. Size the new boiler to the connected EDR, not to square footage and not to the size of the old boiler
3. Check gas line and venting capacity
4. Plan chimney liner if needed
5. Remove old boiler and associated piping
6. New near-boiler piping per manufacturer specs (header, equalizer, Hartford loop)
7. New low-water cutoff, gauge glass, water column, controls
8. New gas connection, pressure test
9. Initial fill, skim test, boil-out (steam boilers need a thorough boil-out to remove oils and cutting compounds from the new piping)
10. First-fire combustion check
11. Verify steam distribution to every radiator, balance vents (one-pipe)
12. Walk-through with the homeowner on water level, blowdown schedule, vents, and seasonal startup

Annual steam boiler maintenance

Steam boilers need more annual care than hot water boilers. The work is not hard but it has to get done.

• Skim the boiler at every startup or service (oils on the water surface cause surging)
• Blow down the low-water cutoff to clear sediment
• Test the low-water cutoff operation
• Inspect and replace gauge glass if it is cloudy or hard to read
• Inspect and replace steam vents that hiss too long or not at all
• Inspect and clean steam traps (two-pipe systems)
• Combustion check
• Pressure control verification (operating limit and vaporstat)

The Wahl Club membership covers this annual visit on every steam install.

Schedule a steam boiler consult

Call 1-855-GET-WAHL (1-855-438-9245) or schedule online. We answer 24/7. Steam is a Pittsburgh specialty and we treat it that way.