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. Texas Service Experts diagnoses it by metering the proving circuit and replaces the failed component to bring your existing ignition back — a quick, defined fix that the same crew can roll into whatever else your fireplace or chimney needs that visit, rather than a standalone service call.

There's specific physics behind that dropout. A standing pilot's thermocouple has to heat until it generates enough millivolts to hold the gas valve's safety magnet open — a healthy one reads roughly 25–30 mV open-circuit. As it weakens with age, soot, or a slightly mis-aimed flame, it still lights but can no longer make enough millivolt to hold the magnet, so the valve snaps shut the second you stop overriding it by holding the knob. We put a meter on it and read the number instead of guessing: a low reading confirms the thermocouple (or thermopile, on a millivolt system) is the part to swap — not the valve.

How this differs from pilot-light-installation: 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. If you had working ignition and a part died, this is the page.

Which side of the interlock has failed is also what separates this from gas-valve work, 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). We don't assume — we meter the thermocouple output and check the valve's hold, so we replace the cheap proving part when that's the cause rather than selling a valve. We also rule out a clogged pilot orifice or a draft pulling the flame off the sensor tip, because a new thermocouple fixes neither of those.

When the assembly really is the cause, replacement is a clean, same-day part-swap. We source the correct thermocouple/thermopile, igniter, or full pilot hood for your appliance valve so the proving circuit functions as listed, mount it so the pilot flame fully envelops the sensor tip, and re-aim the flame for a strong, steady envelope. Then we leak-test the connection by manometer and bubble soap, re-read the millivolt output to confirm it's back in range, and run an ambient CO check before handing the unit back.

We finish 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. The right way to do this 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.