Furnace Repair in Herndon, VA
Furnaces here run from October through April. If yours quits, tell us what it's doing and a licensed contractor who covers Fairfax County will get in touch.
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Seven months of winter nights near freezing wears a furnace down
Herndon needs heat from October through April, seven months of the year. Winter nights average 28°F from December through February, so the burner is cycling on and off for most of the day and night through the whole stretch. Each start puts a little more wear on the igniter and the parts that get the burner lit.
Fairfax County also sees its share of winter storms and wind, and power interruptions come with both. Most furnaces need electricity to run even when the fuel is gas, so a blink in power can mean the burner won't light again on its own until something is reset.
- 7 months
- October through April, your furnace is on duty
- 28°F
- the average winter night it heats against
- 54%
- of homes here heat with gas, so most furnaces here burn gas
- 10 winter storms
- in ten years, the nights a failure hurts most
NOAA nClimDiv, 1991–2020 normals
A new furnace would cut about $120 a year off heating for a typical Fairfax County home.
Estimates for a typical Fairfax County home, compared with an older unit built to the previous federal minimum, from EIA household energy data, Virginia fuel prices and NOAA climate normals. Your home will differ.
Repair makes sense when one part has failed and the heat exchanger is sound.
Replacement makes sense when the heat exchanger is cracked or the furnace keeps needing parts.
Virginia requires HVAC contractors to hold a state license.
Virginia's Board for Contractors is the body that tests and records who holds that license. The license belongs to the contractor, not to any single job. There is one carveout worth knowing. In Virginia, work under $1,000 does not need a licensed contractor. A furnace repair can land on either side of that line depending on what's wrong with it.
For a furnace repair priced above that threshold, the state license is what stands behind the work. Gas furnace repairs involve a gas line connection, and a bad connection there is the dangerous part of the job. More than half the homes in Fairfax County heat with gas, so this is not a rare case here.
Sources: Virginia General Assembly · Virginia Department of Professional and Occupational Regulation
- Why won't my furnace turn on?
- The most common cause is the thermostat, a tripped breaker, or a safety switch that has cut power to the system. Check that the thermostat is set to heat and the temperature is above room level, then check the breaker panel and the furnace's own power switch, which looks like a light switch near the unit. If those are fine, the furnace may be reading a fault through its igniter, flame sensor, or a clogged filter restricting airflow, and it will need a contractor to find which one.
- Why is my furnace blowing cold air?
- In most cases the blower is running before the burners have lit, which is normal for a short stretch after you raise the temperature. If cold air keeps coming for more than a few minutes, the igniter or flame sensor may be failing to light the burners at all, so the blower runs without any heat behind it. A dirty filter can also starve the burners of airflow and trip a safety switch that shuts off the heat while the fan keeps going. Since this can be several different parts depending on what's failing, a contractor will need to check the actual furnace.
- Why won't my furnace pilot light stay lit?
- A pilot that won't stay lit is almost always the thermocouple, the small sensor that tells the gas valve a flame is present. When it wears out or sits out of position, it reads no flame even when one is burning, and the gas valve shuts off to be safe. A draft blowing across the pilot or a dirty pilot opening can cause the same thing. A contractor can tell which it is and replace the thermocouple if that's the cause, since it's a simple part but not one to guess at with a gas system.