Posted on: 5 January 2017
A bright blue flame is a common sight on many furnaces that still rely on pilot-driven ignition. But when that flame turns yellow, it could signal one or more potential problems that may affect the way your furnace operates. The following offers several reasons for a yellow pilot and how to correct those problems.
Poor Oxygen Supply
A healthy blue flame usually indicates a near-perfect combustion process. Unsurprisingly, a steady supply of oxygen is needed to keep this process going. If the furnace's oxygen supply is somehow being overwhelmed by combustion gases venting into the furnace, it could cause the pilot flame to turn yellow and subsequently burn inefficiently.
Check for blockages in the exhaust flue and make sure that combustion gases are not being drawn back into the furnace. If you've recently sealed your home against heat losses, you'll want to make sure it offers enough ventilation to prevent dangerous backdrafts. You may also need to adjust your furnace's venting system to prevent combustion gases from retreating back into indoor spaces.
Poor Gas Pressure
Pilot flames can also turn yellow if there isn't enough natural gas or propane being fed through the pilot orifice. Sometimes this problem can be caused by a malfunctioning gas pressure regulator or other problems further down the gas line. You should have your HVAC technician or a gas company specialist rule out these issues before going any further.
Dirty Pilot Orifice
Healthy pilot flames can also be stymied by a dirty pilot orifice. Over time, remnants of burn fuel and other debris can accumulate within and around the orifice, restricting the pilot light's gas supply. Fortunately, cleaning the pilot orifice is usually a matter of shutting off the main gas supply and removing the pilot assembly from the furnace.
Remove debris from the tip of the pilot orifice using fine grit sandpaper and run a stiff wire through the orifice to dislodge clogs and loose material. Once you've reinstalled your pilot assembly, test the pilot and make sure it works properly.
A draft from an open door or a breach in your nearby wall or window can affect the pilot's operation. In many cases, a strong draft can even extinguish the pilot light altogether. You'll want to check your home for any drafts that could disrupt your pilot flame. In some cases, you may need to have your HVAC technician adjust or replace the thermocouple sensors so that the pilot flame can compensate for the draft strength.
These tips can help you diagnose most pilot issues and keep your flame burning at its healthy blue color. Contact a heating repair company for more information.Share