Pilot Assembly Replacement

Your fireplace has a working ignition system that's stopped proving — and this service replaces the one part that failed, on the system that's already there. The signature complaint is unmistakable: you press and hold the control knob, the pilot lights, and the instant you let go the flame goes out. That's not a mystery; it's a measurement. It's diagnosed by metering the proving circuit and the failed component replaced to bring your existing ignition back, and the standard held in one metro is the standard held in all of them.

The physics behind the dropout is specific. A standing pilot's thermocouple has to heat to where it generates enough millivolts to hold the gas valve's safety magnet open — a healthy one reads roughly 25–30 mV open-circuit. Weakened by age, soot, or a slightly mis-aimed flame, it still lights but no longer makes enough millivolt to hold the magnet, so the valve closes the second you stop manually overriding it by holding the knob. A meter goes on it and the number is read rather than guessed: a low reading confirms the thermocouple (or thermopile, on a millivolt system) is the part to swap, not the valve.

Set against pilot-light-installation, the difference is build versus renew: that service builds an ignition system where none works, choosing the architecture and wiring the interlock from scratch. This service keeps your existing architecture and renews a specific worn part within it. You're not redesigning how the fireplace lights; you're replacing the thermocouple, thermopile, igniter, or pilot hood that aged out of the system you already have. Installation builds; replacement renews. Working ignition with a dead part lands here.

It also differs from gas-valve work in which side of the interlock is at fault, and that distinction is the whole diagnosis. A dropping pilot can mean a weak thermocouple (this service) or, less often, a failing valve magnet that won't hold even on a healthy millivolt signal (valve service). Nothing is assumed — the thermocouple output is metered and the valve's hold checked, so the cheap proving part is replaced when that's the cause instead of selling a valve. The dropout is also confirmed not to be a clogged pilot orifice or a draft pulling the flame off the sensor tip, because a new thermocouple won't fix either of those.

Replacement is a clean, same-day part-swap when the assembly is the cause. The correct thermocouple/thermopile, igniter, or full pilot hood is sourced for your appliance valve so the proving circuit functions as listed, mounted so the pilot flame fully envelops the sensor tip, and the flame re-aimed for a strong, steady envelope. Then the connection is leak-tested by manometer and bubble soap, the millivolt output re-read to confirm it's back in range, and an ambient CO check run before the unit is handed back.

The job closes by lighting it several times and releasing the knob each time, because the only proof that matters for this fault is that the pilot now holds on its own. Documented service here is the right diagnosis — a metered reading, not a parts guess — followed by the correct component and a pilot that stays lit when you let go.