Furnace Repair in Murphy Creek, Aurora

Murphy Creek sits at 5,407 feet in southeast Aurora, which under the NFPA 54 convention removes 13.6% of a gas furnace's rated input: a 100,000 BTU/hr nameplate becomes about 86,400 BTU/hr, and a 96% AFUE condensing unit delivers roughly 82,900 BTU/hr of that into the house. This is a golf-course subdivision built around high-efficiency equipment, and on high-efficiency equipment the failure that ends the heating season is usually not combustion at all. It is water - condensate that the furnace makes by design and then cannot get rid of.

Why do condensing furnaces here fail at the drain rather than the burner?

Because a 90%-plus furnace works by cooling flue gas below its dew point in a secondary heat exchanger, which is exactly how it recovers the last of the heat. That produces liquid water, close to a gallon for every hour a 100,000 BTU/hr unit runs, and it is acidic - typically in the pH 3 to 4 range. That water leaves through an inducer drain port, a trap and a drain line. Any restriction anywhere in that path backs water into the secondary coil, and the furnace shuts down before it ever gets to a combustion problem.

What does the 13.6% derate have to do with condensate volume?

It lengthens the burn. A Murphy Creek furnace producing 86,400 BTU/hr instead of 100,000 runs longer to satisfy the same thermostat call, and condensate volume tracks run time. Over a cold week the drain system here handles more water than the same equipment would at sea level, through the same trap and the same line. That is why a marginal drain - slightly undersized, slightly flat, partly fouled - passes in October and fails in January. The derate does not cause the fault; it decides when the fault surfaces.

Why does a blocked trap look like a pressure switch failure?

Because on most condensing furnaces the pressure switch senses through the same passage the condensate drains through. Water standing in the inducer drain port or a fouled trap changes the pressure the switch sees, so it will not make on a call for heat and the board never opens the gas valve. The homeowner is told the pressure switch failed. Replacing it changes nothing, because the switch was reporting accurately. The correct test is to measure inducer pressure at the switch port, then clear and refill the trap and measure again.

What happens when condensate freezes at 5,407 feet?

It stops the furnace, usually at the worst possible time. Condensate lines routed through unconditioned space - a crawl space, a garage, an exterior wall cavity - can freeze during the coldest stretch, which is also when the furnace is running longest and producing the most water. The result is a furnace that works all autumn and locks out during the first hard cold snap. Vent terminations can ice for the same reason, because condensing exhaust leaves the pipe near the dew point. Both are routing and insulation problems, not equipment problems.

What does acidic condensate do over time?

It corrodes whatever it sits in. The secondary heat exchanger, the inducer housing, the trap and any metal in the drain path are all exposed to water in the pH 3 to 4 range, which is why manufacturers specify particular materials and why a neutralizer is used where local practice or drain material calls for it. A Murphy Creek furnace with white residue around the trap or staining below the inducer is telling you condensate has been going somewhere it should not, and that damage accumulates quietly for years before anything stops working.

Is a high-efficiency furnace still the right choice at this elevation?

Generally yes, and the arithmetic explains why: at 13.6% derate, a 96% AFUE unit still puts about 82,900 BTU/hr into a house from a 100,000 BTU/hr nameplate, where an 80% AFUE unit of the same nameplate delivers about 69,100. The condensing furnace gives back a meaningful share of what altitude takes away. The trade is that it introduces a water management system that has to be installed and maintained correctly, and in Murphy Creek that system is where the service calls come from.

Who permits furnace work here, and where else do you go?

Murphy Creek sits in Arapahoe County within Aurora, so a furnace changeout is permitted work through the city rather than filed by you; drain, trap, inducer and pressure switch repairs generally are not. Nearby we cover the rest of Aurora at the same 5,407 feet, Aurora Highlands 174 feet higher at 14.3%, and Bennett out east at 13.9%. Call 720-807-4050.

Other Murphy Creek-area pages

The crews that cover Murphy Creek also run furnace repair in Aurora, furnace repair in Aurora Highlands, furnace repair in Bennett.

If it is the other system acting up instead, start at AC repair in Murphy Creek.

See furnace repair for the service itself, or everything in Murphy Creek for everything we do there.