Gas fireplace flame goes out and relights

A gas fireplace that lights, goes out, then tries again is usually failing to prove that its flame is there, so the control shuts the gas and starts over. On an electronic unit the flame sensing rod is the first suspect; on a millivolt unit it is a weak pilot or thermopile. Other causes are a remote left in thermostat mode, gas piping that loses pressure when other appliances run, and a vent cap blocked by snow or ice. A typical Sioux Falls repair is a $150 to $300 service call, which often covers cleaning the rod or pilot, rising to $300 to $600 for a pilot assembly or $350 to $700 for a control board. We set the firm number after we have seen the unit.

Check this first

• Is the remote in thermostat mode? Many remotes cycle the burner to hold a set room temperature. That is normal.
• Did it shut off after a long burn? Heat & Glo’s manual says its control module shuts the fireplace down after 9 hours of continuous operation without a command from the RC300 remote. That is a safety feature, not a fault.
• Watch the pilot when other gas appliances start. Napoleon’s troubleshooting chart says that if the pilot goes out, turn on all gas appliances and see whether the pilot flame flutters, diminishes or goes out, especially when the main burner lights. If it does, the gas piping may be undersized.
• Look at the vent cap outside. Heat & Glo lists checking the termination cap for plants, bird nests, leaves, snow and debris as a homeowner task. Napoleon adds that in really cold conditions ice can build up on the terminal and should be removed. Clear a ground-level cap once the fireplace is off and cool. Stay off the roof.
• Look at the flame. Napoleon ties a blue, lazy, transparent main burner flame to a blockage in the vent.

Causes, signs and typical cost

Heat & Glo’s annual technician list includes “Inspect IPI flame sensing rod for soot, corrosion and deterioration. Polish with fine steel wool or replace as required.” The rod sits in the flame and signals the board; soot or corrosion can weaken that signal until the board decides the flame is gone. Napoleon’s chart for a main burner that goes out while the pilot stays on lists a pilot flame not large enough or not engulfing the thermopile, and a thermopile that is shorting. Our pilot light and ignition repair page goes through both.

We also read the pressures. Napoleon’s manual gives an inlet reading of 7 inches water column, minimum 4.5, for natural gas, and 13 inches, minimum 11, for propane. A reading that sags when the furnace lights points at the supply side, not the fireplace.

Why winter makes this worse here

NOAA’s normals for Sioux Falls show 45.3 inches of snow a year and 24.9 nights with a low at or below zero. A side-wall vent cap can be buried by drifting snow or glazed with ice, and Napoleon recommends an insulated sleeve where a vent runs through unheated space. Those are the conditions its manual warns about, and they are the reason our annual service includes the cap.

If the fix turns out to be gas piping, keep in mind that inside Sioux Falls city limits anyone paid for mechanical work must be employed by a city-licensed mechanical contractor, so ask which city licence covers the job.

When to call us

Call if it cycles with the remote out of thermostat mode, if it drops with the cap clear, or if the pilot flutters when other appliances fire. See typical prices on our pricing page.