Furnace Repair in Wheat Ridge, CO

A gas furnace that quits in Wheat Ridge almost always fails at one of five points: flame sensor, hot-surface igniter, pressure switch, high-limit switch, or inducer motor. Which one it is can be identified in a single visit with a meter and a manometer. At 5,459 feet the furnace is also fighting a 13.8% derate on its rated input, and that changes how the symptoms read. MoJo Home Services, family-owned since 2009, works Wheat Ridge at 720-807-4050.

What fails most often on Wheat Ridge furnaces?

Flame sensors lead the list. A clean sensor produces a small DC current in the single-digit microamp range; let oxide build on the rod and the signal falls until the board declares no flame and shuts the gas off seconds after ignition. Igniters are next, and they fail from cycle count more than from age. Pressure switches trip on a blocked flue or standing condensate. High-limit switches trip on airflow. Inducer motors announce themselves with bearing noise weeks ahead of the failure. Nearly every no-heat call in the city lands somewhere in that list.

Why does 5,459 feet change what those symptoms mean?

Take the derate first: 3,459 feet above the 2,000-foot baseline at 4% per thousand gives 13.8%. A 100,000 BTU/h furnace in Wheat Ridge fires at about 86,200 BTU/h, and at 80% AFUE that is roughly 69,000 BTU/h into the house instead of 80,000. Now take the air itself, which is about 15% thinner here than at sea level. The blower still moves its rated cubic feet per minute, but each cubic foot carries less mass and therefore pulls less heat off the exchanger. A blower set for 1,200 CFM is doing the cooling work of roughly 1,020 CFM at sea level. That is why an airflow problem that would be merely marginal at the coast trips a limit switch in Wheat Ridge.

Why does my furnace turn on and off every few minutes?

Short cycling in a 5,459-foot house is usually airflow, not the burner. A loaded filter, a closed-off return, or a blower on the wrong tap raises supply temperature until the high limit opens, the burner stops, the air cools, and the pattern repeats. The second cause is a furnace that was oversized on purpose to cover the 13.8% derate and then oversized again by rounding up to the next available model, so it satisfies the thermostat faster than the heat exchanger wants to be heated and cooled. Diagnosis is measurement: total external static pressure against the nameplate limit, then temperature rise against the nameplate band.

What happens to the flue when only one gas appliance gets replaced?

Plenty of Wheat Ridge homes vent an 80% AFUE furnace and a gas water heater into a single masonry chimney sized for the combined flue volume of both. Replace the furnace with a 90%-plus condensing unit that vents through PVC out a sidewall and the water heater is left alone in a chimney far too large for it, a condition called orphaning. Flue gases cool, condense inside the liner, and at 5,459 feet, with 13.8% less rated input producing them in the first place, draft is weaker to begin with. The symptoms are a damp chimney, spillage at the water heater draft hood, and eventually a carbon monoxide complaint. The correct fix is a properly sized liner installed with the furnace, not two winters after it.

What can I check before calling for furnace repair?

Four things, in about five minutes. Replace the filter if it is grey. Confirm the thermostat is calling and its batteries are fresh. Check that the blower door switch is fully seated, since a door left proud kills the entire sequence. Reset the breaker once. If the unit lights and dies within about seven seconds, stop there and call us; that pattern is flame sensing or gas supply, and repeated resets only add cycles to an igniter that is already the second most common part we replace.

Where else do you work near Wheat Ridge?

Wheat Ridge has 31,192 residents and sits wedged between two much larger cities, so our routes through it usually take in Arvada at 115,368 people to the north and Lakewood at 152,597 to the south, plus Edgewater to the east. All three sit within a couple hundred feet of Wheat Ridge's elevation, so the derate math travels with us and the truck stock does not change from stop to stop.

Where else we work

Nearby and on the same schedule: furnace repair in Arvada, furnace repair in Edgewater, furnace repair in Lakewood.

For the other half of the system, AC repair in Wheat Ridge.

Wider view: furnace repair, or everything in Wheat Ridge.