How to Heat a Steam Boiler

Steam boilers send hot steam through pipes that connect to radiators in the home.

While furnaces heat and distribute air throughout the home, steam boilers send steam through pipes that connect to steam radiators. After the steam vaporizes, it returns to the steam boiler for reheating. Because they operate at higher temperatures than water boilers and consume significant amounts of water to generate steam, steam boilers are less energy-efficient and require more maintenance. Moreover, water feeders must be monitored constantly to ensure a steady supply of make-up water to the steam boilers.

Things You'll Need

• Manual or automatic water feeder
• Water level gauge
• Pressure valve
• Low-water cut-off valve

Instructions

1. Determine whether your steam boiler has an automatic water feed valve or manual water feeder valve. The water feed valve supplies water for the boiler to heat and generate steam. Locate the “manual water feed” button or lever if you need to override the automatic function or use it as an alternative if the automatic feed valve is broken.

2. Look at the sight glass or water gauge to check the boiler’s water level. For manual feeders, add water if the water level has fallen to the “add” mark. Lift up the pressure release valve near the bottom of the boiler until you hear the air release. Release the valve once water begins to flow to the boiler.

3. Locate the “Feed” button on the water feeder if you have an automatic feed valve. Use the counter to check and record the number of gallons required during an automatic feed cycle. Set the water feeder according to the time it takes for the water to reach the middle of the gauge or the make-up limit recommended by the manufacturer.

4. Flush water from the low-water cut-off valve approximately once a week during the heating season. This improves heating efficiency and removes sediments, which can clog the boiler and cause the valve's cutoff controls to malfunction.

Tips & Warnings

• Retrofit your steam boiler to save replacement costs and to improve the safety and efficiency of your heating system. Weigh the expense of adding thermostats or upgrading ductwork versus replacing your steam boiler. Also consider the life span of your current boiler and whether a replacement is likely in the near future.

• Do not add more water than needed to the boiler. Adding water beyond the amount needed for optimal operation causes steam boilers to rust internally, forms deposits and interrupts heat transfer. This can cause steam boilers to overheat and crack, shortening operating life.

References

• in.gov: Winter Operation of Steam and Hot Water Heating Boilers
• e-ComfortUSA.com Programmable Water Feeder for Steam Boilers
• Old House Web: HVAC Steam Heating Systems
• U.S. Department of Energy: Furnaces and Boilers