Local gas fireplace repair for Palm Valley homes

Reading a thermocouple under load

A thermocouple is two dissimilar metals joined at a tip that sits in the pilot flame. Heat at the junction makes a voltage measured in millivolts, and that voltage keeps the valve's safety magnet energized, which holds the pilot gas path open.

A thermocouple can read fine on the bench and still fail in the unit, so we measure it in place, with the pilot burning and the knob held in, and check the number against the troubleshooting chart in the maker's service literature. With a good flame, a low number points to the thermocouple. A good reading with a pilot that still drops points to the valve.

Pressure at the test ports

A fireplace gas valve carries two small test ports, one on the inlet side and one on the outlet or manifold side. A manometer on each tells whether gas is arriving at the pressure the rating plate calls for and leaving at the pressure the burner needs. Low inlet pressure is a supply problem outside the appliance. Correct inlet with low manifold pressure points into the valve or its regulator. Readings are taken with the burner lit, since a supply that looks fine at rest can sag under load, and each port is resealed and leak-checked after.

Burner ports and ember material

The burner is a pan or tube with rows of small ports, and the flame pattern depends on every one of them. Dust, fallen ember material and bits of broken log block ports and make the flame lopsided or uneven. Ember material is its own part: the manual says what kind, how much and where it goes, for example a thin layer over a specific area. Too much of it over the ports smothers the flame and can cause sooting. On service we lift the logs, vacuum the burner, clear the ports and relay the embers as the manual shows.