Thermador Range & Oven Repair

Pro Harmony or Pro Grand?

Thermador sells its professional ranges in two families. Pro Harmony comes in 30, 36 and 48-inch widths, and Pro Grand comes in 36 and 48-inch widths and offers more cooktop and oven choices. A model number starting with PRG is all-gas. PRD means dual fuel, with the gas cooktop over an electric oven. Sealed Star burners come on every model, every burner gets its own electronic igniter with automatic reignition, and many models add ExtraLow burners plus a griddle or grill.

The Star burner's base is shaped like a star, and the cap needs to cover it completely. Put together correctly, a burner lights in four seconds or less and burns blue with no yellow tips.

Clicks, sparks and a cycling flame

Count the clicks. More than four before the burner lights, and Thermador's guide says the cap isn't fitted properly on its base, so reseat it until it covers the star. Sparking that comes and goes is down to a wet or dirty ceramic igniter or clogged ports. Sparking that never stops means the range isn't grounded correctly or the outlet has reversed polarity, which is a job for an electrician, or the spark module is failing.

Igniters that spark without producing a flame may simply have the gas supply valve turned off. If the gas is on, the burner valve needs a technician's look. A range that's completely dead has no power at the breaker or has been left in Sabbath mode.

Then there's the ExtraLow burner that keeps turning itself off and on. That one's normal. On the lowest settings the flame goes on and off inside every minute, which keeps the average heat very low.

Oven trouble on PRG and PRD models

A locked door after cleaning on a dual fuel model isn't a fault. After self-clean the door won't unlock until the oven has cooled to a safe temperature. A gas oven that's slow to heat or bakes unevenly is a different matter, because the bake and broil burners rely on igniters that wear over time. On dual fuel ovens, the usual suspects are the elements, the convection fan and the temperature sensor.

What to try before you book

• Look at the breaker, and make sure Sabbath mode isn't on.
• After cleaning or a spill, let the burners dry out completely.
• Poke the cap ports clear with a straightened paper clip, a sewing needle or a thin wire, then put each cap back so the star base is fully covered.
• Go over the port openings with a stiff nylon brush, and keep chlorine-based cleaners off the range finish.
• During a power outage, turn every knob off. ExtraLow burners and the griddle won't work without power.

E-Nr, FD and Z-Nr

Depending on the model, the rating plate sits behind the kick plate or above the main oven. Copy down three numbers from it, the E-Nr (model), the Z-Nr and the FD (production code). Both Thermador support and parts suppliers want all three, and it's the FD code that decides which parts fit your range.

After the power comes back

Thermador's guide covers what to do after a power failure. Switch off any knob that was left on, then give it five minutes before you light any burner. To light standard burners by hand during an outage, follow your use and care guide, and don't try lighting ExtraLow burners manually. In humid coastal kitchens, water spots and film build up faster, so wipe stainless along the polish lines and dry it immediately.

Fix it or replace it?

A Thermador professional range is built for the long haul, with a steel body, cast grates, and burners, igniters, spark modules, valves, elements and controls that can all be replaced. It's also sized to a specific opening and hood, so replacing one often turns into more than a range swap. Repair is usually the better value, unless the oven cavity is damaged or the controls keep failing.