15-25 Minute Assessment

HVAC: Boiler

Gas boilers use a pilot light or electric starter. Oil boilers have a separate burner that filters and ignites the oil. All types have a temperature and pressure gauge. Steam boilers also have a glass tube called a sight glass.

Get a professional inspection every year, before the heating season starts. Ask your HVAC pro if you need to “flush” or “bleed” your system. If you do, have them show you how.


Every fall

Repair and replacement costs

Typical Costs

  • Inspect: $200 – $500
  • Repair: $200 – $600
  • Replace: $3,600 – $8,000

Life span


15 – 30 years

Steps to Assess Your Boiler


Step 1: To prevent fires and ensure easy access, clean the outside of your boiler and the area around it. Check the outside for dents, cracks, and corrosion. Repair damage ASAP.


Step 2: Check water, electrical, and gas lines for leaks, cracks, or corrosion. Test the shutoff valves and fix any that don’t work.


Step 3: Check the gauges and valves. The manual should list the correct temperature and pressure ranges. If there’s a sight glass, it should be ½ to ¾ full of clean water.


Step 4: Start your boiler. If it doesn’t start, check for a service switch or a tripped breaker. Does it make sounds without heating up? You may need to relight the pilot light or order fuel.


Step 5: After 15 minutes, your radiators should be warm. With older systems, a little hissing and banging is normal. Check around the radiators for water damage and repair any leaks.