No heat in a Colorado January is not just a comfort problem, it is a burst-pipe risk. Call during business hours rather than using the booking form — the phone is faster and no-heat calls get worked into the day where we can.
AT A GLANCE
- System type
- Forced air. For boilers and radiant, see Boilers & Radiant Heat.
- No heat in winter
- Call during business hours rather than booking online
- Typical lifespan
- 15 to 20 years for a well-maintained gas furnace
- Altitude derate
- Required above 2,000 feet and routinely skipped
- Permit required
- Yes for replacement. Pulled by us.
- Best time to replace
- Spring or early autumn, not the first cold night
If you have no heat right now
Call, during business hours. The booking form is for work that can wait, and a house losing heat in single-digit weather is not that — beyond comfort, the real risk is that supply lines in exterior walls and unheated crawlspaces start freezing.
Before you call, it is worth checking three things, because they account for a large share of no-heat calls and you can resolve them yourself in two minutes: thermostat batteries, the furnace service switch, and the filter.
This page is about forced-air furnaces — the kind that heat air and blow it through ducts. If your heat comes from radiators, baseboard or a warm floor, that is a boiler, and it is a different animal with different failure modes.
Altitude, and why it matters more here than almost anywhere
This is the single most consistently mishandled thing in Front Range HVAC. Combustion needs oxygen, and there is measurably less of it per cubic foot at six thousand feet than at sea level. Furnace manufacturers publish specific derate procedures for high-altitude installation — orifice changes, manifold pressure adjustments, sometimes different kits entirely.
A furnace installed by someone who skipped that runs fuel-rich. That means wasted gas, sooting, shortened heat exchanger life, and in the worst case elevated carbon monoxide. When we are called to look at a unit somebody else put in, this is one of the first things we check, and we find it wrong often enough to make a point of mentioning it.
Sizing on replacement
The default on a replacement is to fit whatever size was there before. That is a guess inheriting an older guess, and oversizing is the usual result.
An oversized furnace short-cycles: it satisfies the thermostat quickly, shuts off, and starts again a few minutes later. That gives you uneven temperatures, more wear on ignition components, and worse humidity behaviour than a correctly sized unit running longer, gentler cycles. We calculate the load against the actual house — insulation, window area, orientation, air sealing — because a house that has been re-windowed and insulated since 1994 does not need what it needed in 1994.
COMMON QUESTIONS
My furnace stopped working. What should I check first?
Three things before you call. Is the thermostat calling for heat and does it have working batteries. Is the furnace switch — which looks like an ordinary light switch near the unit — turned on. And is the filter clogged, because a badly blocked filter will trip the high-limit and shut the furnace down as a safety response. If all three are fine, call us.
Should I repair or replace my furnace?
The honest rule of thumb is age against repair cost. Under about twelve years, repair almost always wins. Past about eighteen years, a major repair is usually money spent on a unit that will need replacing soon regardless. Between those, it depends on the specific failure — a heat exchanger crack means replace, a control board does not. We will tell you which one you have and let you decide.
What does altitude have to do with my furnace?
A great deal, and it gets skipped constantly. Air at six thousand feet is roughly eighty percent as dense as at sea level, so a furnace draws proportionally less oxygen for combustion. Manufacturers publish derate procedures for high altitude, and a furnace installed without them runs rich, wastes fuel and can produce carbon monoxide. It is one of the first things we check on a unit somebody else installed.
How often should a furnace be serviced?
Once a year, ideally before heating season rather than during it. The service that matters is combustion analysis, heat exchanger inspection, and checking the flue — not just changing a filter. That is what catches a cracked heat exchanger before it becomes a carbon monoxide problem.
How long does a furnace replacement take?
A straightforward like-for-like replacement is typically a single day. If venting has to change, or if the new unit is a different configuration, it can run into a second day. We schedule inspection separately so it does not hold up getting your heat back on.