Propane and natural gas fireplace repair in Zellwood

How a millivolt standing pilot system works

A millivolt system makes its own power from the pilot. On the millivolt pilots in two vent manuals, the pilot splits into three distinct flames. One heats the thermocouple, one heats the thermopile and one reaches toward the main burner.

Each of those two parts turns the heat into a small voltage. The thermocouple's output holds the pilot safety in the gas valve, and when it fades the pilot safety drops out. The thermopile's output powers the switch or remote circuit that opens the main burner, which is why one Heatilator manual says house power on its standing pilot units serves optional accessories and warns that wiring line voltage to the millivolt valve damages it.

A fault can sit in any link of that chain, from a weak thermocouple or tired thermopile to a loose lead, a switch or the valve itself. For Zellwood homeowners, each link is tested in order before a part goes on the estimate.

Leak checks on the appliance connections

A yearly service list we follow includes a leak check of every accessible gas-carrying tube, connection and fitting. The fuel gas code allows leaks to be located with an approved gas detector, a noncorrosive leak detection fluid or another approved method, and the fireplace manuals add that an open flame is never used.

One natural vent manual also warns against spraying solution onto the control body, and notes that excess pipe compound can set off an electronic detector. A leak on the appliance's own valve, pilot or burner joints is part of the fireplace repair, while one on the connector or the supply piping is referred to the plumber or gas installer who works on house piping.

Any fitting disturbed during a repair is checked before the fireplace is lit again, as the installation manuals direct. On repair and service visits in Zellwood, our technician uses that manual's list of points as a guide.

• The pipe from the supply connection to the gas valve
• Every joint on the valve and control body
• The burner and pilot connections
• Field-made and factory-made joints alike

Grounding and the fireplace circuit

Any fireplace with a fan, lights or electronic ignition is also an electrical appliance. The manuals we have read require it to be wired and grounded per local codes or, where there are none, the National Electrical Code. Florida's fuel gas code adds a rule that is easy to miss. Gas piping shall not be used as a grounding electrode.

Ground matters to the ignition as well as to shock safety. An electronic ignition troubleshooting table lists poor or no system ground as a cause of a pilot that sparks but never lights, and has the ground wire on the valve wiring checked at the metal chassis. A natural vent chart from another maker notes that a poor or erratic ground may cause an occasional shutdown even when the fireplace works normally at checkout.

Inside the appliance, our technician tests the ground connections and labels wires before disconnecting any control, as the manuals direct. A fault in the house wiring is noted on the estimate for a qualified electrician.

Ticking and pinging as the fireplace heats

Steel moves as it heats and cools. A question table in one owner's manual describes a metallic noise caused by metal expanding and contracting, like a furnace or heating duct, and says it does not affect the operation or longevity of the appliance. Two vent manuals from another maker call the same start-up and cool-down sounds normal for fireplaces made of steel.

Timing separates normal from not. Expansion noise shows up as the unit warms and again as it cools, then settles. A steady grind, rattle or hum that lasts as long as the fan runs comes from a moving part, and a sound that began after a repair or after the logs were moved deserves a mention.

On service visits in Zellwood, our technician listens through a lighting cycle before deciding that a noise needs a part. If it is only expansion, you hear that plainly and nothing is added to the estimate.