Furnace Repair in Erie, CO

Erie sits at 5,026 feet in Boulder County, putting the gas derate at 12.1% - the gentlest correction anywhere we work, and still 12,100 BTU/hr off a 100,000 BTU furnace. The fault we are called out for most here is an ignition sequence that starts and never finishes: the inducer spins, the igniter glows, and the burners either fail to light or light late with a thump. MoJo Home Services, 720-807-4050.

What happens during a furnace ignition sequence, and where does it break?

Six steps, each one proving the last. The thermostat closes a 24-volt circuit. The inducer starts and pulls the negative pressure that closes the pressure switch. The board energises a hot surface igniter - silicon nitride on newer equipment, silicon carbide on older - for roughly 17 to 45 seconds. The gas valve opens. The flame sensor proves flame within a few seconds. The blower starts on a fixed delay. In Erie the break is usually between steps four and five: gas arrives but the burners do not light cleanly, or flame is not proved, so the board retries three times and locks out for an hour. A homeowner hearing the same false start once an hour is listening to a lockout timer, not a failing thermostat.

Why does an Erie furnace ignite late with a bang?

That is delayed ignition. Gas collects in the burner box a fraction of a second longer than it should before the flame reaches it, then all of it lights at once. The causes are mechanical and every one is findable: carbon or rust flakes partly blocking burner ports, a cracked or high-resistance igniter that heats slowly, a misaligned crossover between burners, a gas valve slow to reach full manifold pressure, or a burner compartment short of combustion air. It is not cosmetic. Each thump drives a pressure pulse into the heat exchanger, and repeated over a winter that is one of the genuine mechanisms behind exchanger cracking.

Is a 12.1% derate small enough to leave alone in Erie?

No, and the ignition system is where skipping it shows up. Erie's 12.1% takes a 100,000 BTU/hr furnace down to roughly 87,900 and an 80,000 BTU unit to about 70,300. That correction applies whether or not anyone applied it. Leave a furnace at sea-level manifold pressure at 5,026 feet and it is over-fired for the oxygen available per cubic foot, producing a richer flame, more soot on burner ports and sensor rods, and precisely the delayed-ignition and flame-proving faults above. The towns around Erie sit in a narrow band and none share its number: Frederick at 4,984 feet derates 11.9%, Lafayette at 5,210 feet 12.8%, Broomfield at 5,394 feet 13.6%.

How do you tell an igniter fault from a gas valve fault?

With a meter and an order of operations. A hot surface igniter is read cold for resistance - silicon carbide typically in the tens of ohms, silicon nitride higher - and then live for current draw as it heats. An open igniter reads infinite resistance and never glows. One that glows but draws high current or shows visible hot spots is failing and often ignites late. If the igniter is sound and the board sends 24 volts to the gas valve terminals while no gas arrives, the fault sits at the valve or its supply: a closed shut-off, low inlet pressure, or an open valve coil. Metering the valve terminals separates those two paths in under a minute.

Why does my Erie furnace lock out at night and run fine the next morning?

Because cold weather stacks load onto a system already 12.1% short. Longer run times raise cabinet and exchanger temperatures, so a marginal limit switch or a heat-widened igniter crack opens when it did not at milder outdoor temperatures. On condensing equipment the same night finds a condensate trap that is slow, mis-pitched or iced at the termination; the pressure switch opens and the board locks out. On 80% equipment, wind against a sidewall or chimney termination can spill the vent long enough to break the draft signal. All three clear themselves by mid-morning, which is why the "it was working when you got here" call is so common in Erie.

What fails most often across Erie's 21,420 residents?

Igniters and flame sensors lead, because they are consumables that see every cycle. Pressure switches and their tubing follow, usually a blocked port or cracked hose rather than a failed switch. Then inducer motors, limit switches, condensate traps and gas valves. A town this size carries both recent construction and older stock, so the same symptom can arrive from a two-year-old condensing furnace and a twenty-year-old atmospheric one in the same day.

What does furnace work in Erie need for permitting?

Repairs - igniters, flame sensors, pressure switches, inducers, gas valves, limit switches - carry no permit requirement. A furnace replacement at an Erie address is permitted through the building authority serving the town within Boulder County, and that permit takes in the venting and gas connection alongside the appliance. MoJo is licensed, insured and EPA-certified, files it as part of the installation, and commissions the replacement for 5,026 feet on the day rather than leaving factory settings for the next technician to find.

Same crews, neighbouring towns

Nearby and on the same schedule: furnace repair in Lafayette, furnace repair in Broomfield, furnace repair in Frederick.

Heating and cooling fail for different reasons in the same house — see AC repair in Erie.

More: furnace repair · everything in Erie.