Furnace Repair in Aurora, CO

Aurora is the largest city MoJo Home Services covers, 359,407 residents, and at 5,407 feet its gas furnaces run a 13.6% derate. A 100,000 BTU/hr nameplate fires roughly 86,400 BTU/hr here; on a 92% AFUE furnace that is about 79,500 BTU/hr of delivered heat. What most Aurora no-heat calls actually turn on, though, is not the burner rating. It is airflow, because the same 5,407 feet that thins combustion air also thins the air the blower has to push.

Why does thin air make the blower the deciding component?

A furnace does not heat cubic feet, it heats pounds of air. At 5,407 feet a cubic foot weighs noticeably less than at sea level, so a blower moving its rated CFM is moving less mass, and less mass carrying the same BTUs leaves the plenum hotter. Temperature rise climbs toward the top of the nameplate band, commonly 30 to 60 degrees F on modern equipment, and if the duct system is even slightly restricted it goes past the top. The high limit opens, burners shut down, the blower keeps turning, and the whole thing restarts minutes later. That is Aurora's most common winter complaint, and it is an air-side fault rather than a thermostat fault.

What should temperature rise read on an Aurora furnace?

Whatever the data plate specifies, measured correctly: probes in the supply and return plenums out of line of sight of the exchanger, read after ten minutes of steady firing. If the plate says 35 to 65 and the appliance is running 70, the answer is airflow or fire rate, not a larger furnace. With Aurora's 13.6% derate the burner is already making less heat than the label promises, so a high rise means the air side is worse than it appears: choked returns, a crushed flex run, a filter chosen for filtration rating rather than pressure drop, or a blower tap left where it was set for a different house.

Where does static pressure fit in the diagnosis?

It is the reading that separates a blower problem from a duct problem. Most residential furnaces are rated at 0.5 inches of water column total external static, and a large share of the systems we test in Aurora run well above that, meaning the blower is already fighting the ductwork before altitude enters the conversation. We measure across supply and return with a manometer, then compare the resulting airflow to what the appliance requires. A PSC blower simply loses CFM as static climbs. A variable-speed ECM ramps up to hold airflow and hides the restriction until it draws more power, gets louder, and fails early.

Does a city of 359,407 have a typical furnace?

No, and that is the practical difficulty of covering Aurora. The city spans an unusually large area with housing that runs from decades old to newly finished, so a technician can spend the morning on a natural-draft furnace vented into masonry and the afternoon on a sealed-combustion modulating unit with PVC through the wall. What does not vary is the 13.6% derate at 5,407 feet and the obligation to measure instead of assume: gas pressure, temperature rise, static pressure, flame signal, combustion.

What actually fails on Aurora blowers?

Run capacitors lead. A weak capacitor drops blower speed, pushes rise up and trips limits, and it is an inexpensive part regularly misdiagnosed as a dying motor. Next are blower wheels loaded with dust, which lose a surprising amount of CFM without ever sounding wrong. Then motor bearings, ECM control modules, and limit switches cycled so many times by an unresolved airflow fault that they finally stop resetting. Replacing a tripped limit without establishing why it tripped is how a furnace comes back a month later.

Who permits furnace work inside Aurora?

Aurora permits its own building work, which matters because the municipality extends across more than one county line. The Aurora addresses in our service data are recorded under Adams County, while communities immediately south of them fall in Arapahoe. For furnace work the practical answer is the same in either case: the city permits a changeout, component repairs generally are not permitted, and we file the paperwork rather than handing it to you.

Where in and around Aurora does MoJo work?

Across the city and the communities carrying its name at different elevations: Aurora Hills at 5,515 feet, Aurora Highlands at 5,581, and Murphy Creek, which shares Aurora's 5,407-foot reference elevation exactly. One number for all of them: 720-807-4050.

Nearby towns we cover

If you are comparing notes with someone a town over, we cover furnace repair in Aurora Hills, furnace repair in Aurora Highlands, furnace repair in Murphy Creek too.

The opposite season has its own failure list: AC repair in Aurora.

Background on the service is at furnace repair; the full local list is at everything in Aurora.