Failures get names, not guesses.
FurnaceWatch does state-based diagnosis: it knows what a normal heating cycle looks like, and when a cycle goes wrong it tells you which way. Not a prediction — a diagnosis, the moment it happens.
Heat call with no ignition
The thermostat is calling for heat and the furnace has not fired — the no-heat call, caught before the house gets cold.
“Thermostat calling for heat since 5:42 AM. The furnace has not fired.”
This is the emergency you usually hear about from a cold customer. Now dispatch starts from the alert, not the complaint.
Igniter failure
The ignition sequence started — the inducer ran — but no flame was ever detected.
“Heat call at 6:05 AM: inducer ran its start sequence, no flame detected.”
Flame never established — most often the igniter. The tech rolls with a compatible igniter and the timeline of what did and didn’t run.
Flame sensor failure
The flame lit, dropped out within seconds, and the furnace retried until it locked out.
“Flame detected and lost within seconds, three tries in a row — furnace has locked out.”
The failed flame-proving pattern: the flame burns but is never sensed, so the control shuts the gas off and retries. Usually a dirty or failed flame sensor — a quick first-visit fix when you arrive knowing.
Pressure switch / rollout trip
The inducer ran, but ignition never followed — a safety is holding the furnace off.
“Inducer running, no ignition activity detected — a safety appears to be holding the furnace off.”
A safety is doing its job. The tech arrives ready to find out why instead of starting from “no heat.”
Short cycling
The furnace is starting and stopping without completing normal cycles.
“Nine cycles in the last hour, none longer than four minutes.”
Caught while it is still a service visit, not yet a no-heat emergency or a damaged component.
Extended run
A heating cycle running far past normal length.
“Current cycle has run 3× longer than this furnace’s normal cycle.”
Something is keeping the furnace from satisfying the call — worth a look before the customer notices.
Sensor offline
The sensor stopped reporting — flagged, so no furnace is ever silently unwatched.
“Sensor has not reported for 2 hours (last seen 6:14 AM).”
Usually the home’s Wi-Fi. Detection keeps running on the sensor; the portal tells you the unit is unwatched.
What it doesn't claim to catch
FurnaceWatch diagnoses failures as they happen. It does not predict when a component will fail, estimate remaining life, or measure wear. If a monitoring product tells you it can, ask how. And as detection grows to cover more failure modes, this page is where they'll show up — not before.
Want to see an alert land?
Book a demo and watch a failure get named — on the sensor, in the portal, and on a phone.