Furnace Repair in Hampden, Denver CO

Hampden is the stretch of south Denver along East Hampden Avenue, sitting at 5,525 feet, and gas furnaces here surrender 14.1% of rated input to altitude. An 80,000 BTU/h nameplate is worth about 68,700 BTU/h of input here, a 120,000 BTU/h unit roughly 103,000. The pattern that sets this neighborhood apart from newer parts of Denver is venting: a great deal of the heating equipment here is still atmospheric, drafting up a masonry chimney that was built for a different appliance than the one now attached to it.

Why does an 80% furnace on a masonry chimney spill in Hampden?

An atmospheric furnace has no inducer forcing the flue gas out. It relies on hot gas being buoyant enough to climb a cold chimney on its own. Three things here work against that. The chimney is masonry on an exterior wall, so it starts each cycle cold. The furnace is firing 14.1% below its nameplate at 5,525 feet, which makes for slightly less flue heat to establish that draft. And the house has a kitchen hood, bath fans and a dryer that can pull the basement negative faster than a weak draft can resist. The result is spillage at the draft hood, which is a combustion safety problem and the first thing we test for on any atmospheric appliance in this neighborhood.

How much does 5,525 feet actually cost, and how do neighbors compare?

Hampden stands 3,525 feet above the 2,000-foot rating threshold, so 14.1%. The useful comparison is how quickly that shifts across a short drive: Glendale is 174 feet lower at 5,351 feet and derates 13.4%, and Englewood at 5,371 feet derates 13.5%. Under a mile of ground can move the number two-thirds of a point, which on a 120,000 BTU/h furnace is roughly 800 BTU/h. That is why manifold pressure gets verified per address instead of per city, and why a nameplate carried over from a job in Denver proper is a starting point rather than an answer.

What does a lazy yellow burner flame mean in a Hampden furnace?

A properly set gas burner runs a crisp blue flame. Yellow, lifting or lazy flame means the fuel-air mixture is off, and at 5,525 feet the two usual causes are an orifice never corrected for altitude and a burner or heat exchanger passage fouled with rust and lint. Both produce incomplete combustion, and incomplete combustion in an atmospheric appliance with marginal draft is how carbon monoxide gets into a house. Soot on the burners, a scorched draft hood or a rusted flue collar are visible symptoms of the same condition. The remedy is combustion testing with the flue analyzed, not a guess at the gas valve.

Why do the rooms farthest from the furnace never keep up?

Postwar houses were ducted for the system they had, and many were later modified: a basement finished, a room added, air conditioning fitted to a duct system designed only for heating. Returns are typically the shortfall, and undersized returns raise static pressure, cut total airflow and starve the longest supply branch first. The furnace runs, the near rooms overheat, the far room stays cold. With 14.1% already off the top there is no reserve output to force through a restricted system, so the measurement that matters is static pressure across the air handler before anyone talks about a bigger furnace.

When is an older Hampden furnace not worth repairing?

When the heat exchanger is breached. Everything else, igniters and thermocouples, gas valves, blower motors and capacitors, limit switches and boards, is economic on a sound unit regardless of age. On older atmospheric equipment the exchanger inspection carries more weight than it does on newer sealed-combustion furnaces, because a crack in an appliance drafting up a marginal masonry flue puts combustion products in the return air stream. If the answer is replacement, changing to a condensing furnace means the chimney no longer carries the furnace at all, which raises the question of what else is vented into it.

Who permits the work in Hampden?

Hampden is inside the City and County of Denver, so Denver holds jurisdiction: a furnace replacement is permitted work, component repairs generally are not. If a water heater shares the chimney with the outgoing furnace, that appliance has to be part of the plan rather than an afterthought, because a flue sized for two appliances drafts poorly with one left on it. MoJo Home Services, licensed and insured, family-owned since 2009: 720-807-4050.

Where else we work

Nearby and on the same schedule: furnace repair in Glendale, furnace repair in Denver, furnace repair in Englewood.

For the other half of the system, AC repair in Hampden.

Wider view: furnace repair, or everything in Hampden.