Furnace Installation in Gaithersburg, MD
A new furnace here will run from October through April every year. Tell us about the house, and a licensed contractor who covers Montgomery County will get in touch.
Tell us about the job
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Seven months of heat, and nights near 27 degrees
Gaithersburg needs the furnace on from October through April. That is seven months of the year, and winter nights average 27°F. A new furnace has to hold up to that stretch without a break.
More than half the homes here heat with gas, and any non-weatherized gas furnace built since November 2015 has to reach at least 80 percent AFUE by law. Montgomery County also sees its share of winter storms and damaging wind, and in 2024 about 11 percent of Maryland households lost power for a day or more. Whatever furnace goes in should be one that comes back on by itself once the power does.
- 7 months
- October through April, your furnace is on duty
- 27°F
- the average winter night it heats against
- 53%
- of homes here heat with gas, so most furnaces here burn gas
- 80% AFUE
- the federal minimum any new unit must meet
NOAA nClimDiv, 1991–2020 normals
A high-efficiency gas furnace would save about $110 a year to run in Montgomery County compared with a gas furnace.
Estimates for a typical Montgomery County home, from EIA household energy data, Maryland fuel prices and NOAA climate normals. Your home will differ.
Maryland requires HVAC contractors to hold a state license.
The state tested this contractor and keeps a record of them through the Maryland Board of Heating, Ventilation, Air Conditioning, and Refrigeration Contractors. That license belongs to the contractor, not to this particular furnace. It means the person or company doing this job met the state's standard for the trade.
The furnace itself gets checked by the local building office. In most cities and counties, a furnace installation needs a permit, and the work gets inspected once it is done. That inspection is what catches a bad gas connection or a venting mistake, the kind of error that makes a furnace dangerous rather than just broken. More than half the homes in Montgomery County heat with gas, so that connection is not a small detail here.
Sources: Maryland General Assembly · Maryland Department of Labor
- What size furnace does my house need?
- The right size comes from a load calculation, not the square footage of your house alone. A contractor measures your windows, insulation, ceiling height, and duct layout, then runs a Manual J calculation to find the BTU output your home actually needs. A furnace that is too small will run constantly and still leave the house cold on nights near 27 degrees. Skip the online size charts and have a contractor measure your house.
- How do I know it's time to replace my furnace?
- Watch for uneven heat, rising bills for the same comfort, or a repair that costs a large share of a new unit. Furnaces here run seven months a year, October through April, so a weak system gets tested often. If yours needs a repair every winter, or the heat exchanger is cracked, replacement usually makes more sense than another repair. A contractor can look at the unit and tell you honestly which way to go.
- Is a high-efficiency furnace worth it?
- It depends on how long you plan to stay in the house and what you're replacing. Every furnace built new today has to reach at least 80 percent AFUE, so even a standard model wastes less fuel than older units did. A high-efficiency furnace sends less heat out the flue than that, and over a seven-month heating season that difference shows up in gas use. More than half the homes in Montgomery County heat with gas, so it's worth asking a contractor to price both options for your house and let you compare.