Furnace Sounds by Treat’s Heating & Cooling

It is disturbing when you turn your furnace on and hear a loud boom.  There are a few common reasons that this is happening.  Delayed ignition and expanding air ducts. 

If your furnace makes a clicking noise trying to turn on and then makes a loud bang noise right at the furnace location, it is most likely delayed ignition.  If the noise originates a few feet away from the furnace when the blower turns on, the problem may be expanding air ducts.

If you can imagine a closed space full of gas and then someone lights a match; that is what happens with delayed ignition. 

When your furnace is working correctly

  • The thermostat calls for heat from the furnace the gas valve opens and sends gas to the burners where it’s then ignited by the igniter (or pilot light in older furnaces).
  • Heat from the burner flames heats the heat exchanger
  • Your blower blows air over the heat exchanger and pushes heated air throughout your home.

A variety of issues can delay the combustion of gas so the gas builds up in the furnace until BOOM it ignites, causing a mini explosion.  This can harm the heat exchanger.

Causes of delayed ignition

  • Dirty Burners
  • Flames lifting away from the burner outlet due to too much primary air
  • Too much gas

Expanding air ducts can cause a loud banging noise.  This usually means too much static pressure in the ductwork.  Static pressure is pressure in a confined space.  There is too much pressure pushing your ductwork causing it to expand and make the loud noise.

Causes of high static pressure

  • Undersized ducts
  • Closed supply vents
  • Dirty air filter

If you are experiencing any of these problems call Treat’s Heating & Cooling at 360.825.0800 for a professional opinion. 

The Enumclaw, WA furnace experts at Treat’s Heating & Cooling offer high quality installation, repair, maintenance, and other heating and air conditioning services throughout Western Washington including Enumclaw, Buckley, Bonney Lake, Sumner, Puyallup, Tacoma, Auburn, Black Diamond, Covington, Maple Valley, Federal Way, Kent, & Seattle WA.