Sterling holds two eras of Loudoun County housing about thirty years apart, and which one you live in decides almost everything about your heating system.
Sterling Park, 20164. Among the oldest suburban housing in the county. Ranches and split levels with gas furnaces that have been replaced two or three times inside the same basement corner, still connected to the original ductwork and one large hallway return.
Cascades and Countryside, 20165. Late 1980s through the 1990s. Larger houses, frequently two systems, sealed combustion furnaces venting in PVC out a side wall, plus heat pumps across a lot of the townhouses. Most are on their first or second furnace and those are now in the twenty to thirty year band.
What both share: no boilers. Sterling is furnace and heat pump country, which keeps the diagnosis list short.
If you are in Sterling Park
The equipment is newer than the house, and the mismatch is the story.
Short cycling and a cold back bedroom. Usually an oversized furnace on undersized ductwork. Somebody replaced a 1970s furnace by matching the old unit’s BTU rating instead of measuring the house, so it blasts, satisfies the thermostat by the hallway, and shuts off before the far rooms catch up. Nothing is broken. The system is wrong, and no repair fixes it. The fix is sizing the next one properly.
Cold floors and cold far rooms while the thermostat reads fine. Duct losses in a crawlspace, where decades of settling pull flex ends loose. This is not a furnace repair and a new furnace will not solve it. It is usually the cheapest real improvement available in a house of this era.
The furnace overheats and shuts down after fifteen minutes. Airflow again. Filter first, then the blower wheel at $300 to $440, then the return, which is typically one grille doing a job that needs two.
If you are in Cascades or Countryside
Original or second equipment hitting the age where parts start asking for attention.
Lights, runs a few seconds, shuts off, retries. Flame sensor, $95 to $180 to clean. The most common no-heat call anywhere.
Clicking, no flame. Hot surface igniter, $240 to $410.
A whine or rattle before the burners light. The inducer motor, which clears the flue before ignition. When it fails the furnace will not light at all. About $1,950, and a real decision point on a thirty year old unit.
Water near a high efficiency furnace, or one that will not start. Condensate trap, $175 to $420.
One zone warm, one cold on the same system. A zone damper or its motor in a two system house, not the furnace.
Heat pump iced over and staying that way. Defrost board most often, $450 to $1,150. Switch to Emergency Heat and call before the ice reaches the fan blades.
Repair prices
- Diagnostic visit: about $99.
- Flame sensor cleaned $95 to $180; igniter or sensor replaced $240 to $410.
- Condensate drain or trap $175 to $420. Thermostat $300 to $640.
- Blower wheel cleaned $300 to $440. Blower motor $670 to $2,400.
- Control board $550 to $1,180. Inducer motor about $1,950.
- Heat pump defrost board $450 to $1,150. Capacitor $240 to $370.
- Cracked heat exchanger: not a repair. Here is why.
Replacing, in either half of town
A furnace alone runs $4,498 to $12,300 installed; a furnace and air conditioner together $8,898 to $23,000 by system size.
In Sterling Park, insist on measurement rather than matching the outgoing sticker, and ask about the return while somebody is there. In Cascades, if the air conditioner is the same age as the furnace, which it usually is, do both at once: one permit, one crew day, and less total cost than two jobs two years apart.
Washington Gas is paying $500 on a furnace at 95.1 to 96.9 percent efficiency and $700 at 97 and up, through contractors in its network. The federal tax credit ended for anything placed in service after December 31, 2025.
The furnace and AC estimator gives you the installed range for your size in about two minutes with no phone number.
October list
Run the heat for an hour and listen to the first two minutes: inducer, igniter, burners, blower, in order, no hesitation. Change the filter. Clear leaves from around and under any heat pump outdoor unit, since it drains defrost water out the bottom.
Put a carbon monoxide alarm on each sleeping floor. Virginia requires them in new construction with fuel burning appliances and has no retrofit rule, so Sterling Park houses generally have one only if somebody bought it, and the ones installed in Cascades when it was built are past their service life.
SwiftPro repairs heating systems across Sterling and Loudoun County. Call (703) 997-9757, book online, or see the Sterling furnace repair page.
