Furnace Repair in Eldorado Springs, CO

Eldorado Springs is the smallest community on this part of our map — 585 residents in Boulder County — and at 5,732 feet its gas furnaces lose 14.9% of rated input to altitude. The interesting consequence of that number is not the missing heat. It is the extra run time required to make it up, and what those additional burner hours do to a furnace over a decade. MoJo Home Services repairs gas furnaces in Eldorado Springs. Licensed and insured, 720-807-4050.

How much more does a furnace run at 5,732 feet?

Only 85.1% of the nameplate input burns at this elevation, so the burner has to stay lit 1 divided by 0.851 times as long — a factor of 1.175. Every 100 hours of burner time in a sea-level version of the same house becomes about 118 hours in Eldorado Springs. Nothing is wrong when that happens; it is the arithmetic working correctly. But it is 18 extra hours of inducer rotation, gas valve actuation and heat exchanger expansion for every hundred a manufacturer's design life assumed.

Which parts wear out first from the extra hours?

Two different clocks run inside a furnace, and it helps to know which one a part answers to. Inducer motor bearings, blower bearings and belt-driven components wear per hour, so the 17.5% uplift hits them directly. Hot surface igniters, flame sensors, gas valve solenoids and pressure switch diaphragms wear per cycle instead, and those are affected by how the furnace is sized and controlled rather than by altitude alone. An Eldorado Springs furnace that is correctly sized runs fewer, longer cycles and trades cycle wear for hour wear — which is generally the better trade, since bearings give warning and igniters do not. Sizing, in other words, decides which clock a furnace ages by, and altitude only sets the speed of one of them.

What does the 14.9% derate cost in absolute terms?

Multiply the nameplate by 0.851. A 100,000 BTU per hour furnace fires about 85,100 in Eldorado Springs, and an 80,000 unit about 68,100. At 80% efficiency that 100,000 nameplate puts roughly 68,100 BTU per hour into the ductwork rather than the 80,000 the label suggests. If a replacement is on the table, the sizing runs the other way: divide the measured design heat loss by the efficiency and by 0.851 to find the nameplate input the house actually needs. Skipping the 0.851 step leaves an Eldorado Springs house roughly 15% short on the coldest nights of the year.

How often should a furnace at this elevation be serviced?

Annually, and the reason is the run-time arithmetic rather than a marketing schedule. A service interval expressed in years is really a proxy for hours, and Eldorado Springs furnaces accumulate those hours 17.5% faster than the interval assumes. The visit that earns its place is the one that measures — flame sensor microamps, manifold pressure against the manufacturer's high-altitude column, static pressure across the air handler, temperature rise against the nameplate band, and a look at the heat exchanger. A filter change and a visual inspection is not a service.

In what order should a no-heat call here be worked?

Power and thermostat call first, then the filter and return path, then the ignition sequence watched end to end — inducer start, pressure switch closure, igniter warm-up, gas valve open, flame proof, blower delay. Watching the sequence tells you which stage fails, and each stage points at a short list of components. Only then do the meters come out. Working in that order matters more in a community of 585 than it does in a city, because a second visit for the wrong part is a longer wait for the homeowner.

Where else in Boulder County does MoJo work?

Eldorado Springs is the highest of the Boulder County communities we cover. Boulder sits 404 feet lower and derates 13.3%, and Lafayette lower again at 12.8%, so an identical furnace loses 2.1 more percentage points of input here than it would in Lafayette. Golden, over in Jefferson County, is the closest match at 14.7%. Furnace replacement in Eldorado Springs is permitted through Boulder County rather than the City of Boulder.

Same crews, neighbouring towns

Neighbouring work: furnace repair in Boulder, furnace repair in Golden, furnace repair in Lafayette.

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

More: furnace repair · everything in Eldorado Springs.