Furnace Installation in Leonardtown, MD
A new furnace here will run from October through April every year. Tell us about the house, and a licensed contractor who covers St. Mary's County will get in touch.
Tell us about the job
It takes about a minute.
Seven months of heat, and a grid that doesn't always hold
Furnaces in Leonardtown run October through April, seven months a year. Winter nights average 29°F, so the burner is cycling on and off most nights of that stretch. That is a long season for any furnace to carry.
Most homes here heat with electricity, and the power does not always stay on. Maryland saw 11% of households lose power for 24 hours or more in 2024, and St. Mary's County has logged 14 winter storms and 146 damaging wind events over the past ten years. A new furnace should be able to restart on its own once power comes back. If you are installing a gas furnace, federal rules now require it to reach at least 80 percent AFUE.
- 7 months
- October through April, your furnace is on duty
- 29°F
- the average winter night it heats against
- 80% AFUE
- the federal minimum any new unit must meet
NOAA nClimDiv, 1991–2020 normals
Maryland requires HVAC contractors to hold a state license.
Maryland licenses HVAC contractors through the Board of Heating, Ventilation, Air Conditioning, and Refrigeration Contractors. The license is issued to the contractor, not to the job, so it covers this installer's standing with the state rather than a sign-off on your specific furnace. The board is the body that tested and records that contractor, and that record exists whether the job is a repair or a full replacement.
For this job, that license tells you the person in your home is who the state says they are. What checks the furnace itself is a separate process. In most cities and counties, a furnace replacement needs a permit from the local building office, and the completed work gets an inspection before it's considered done. That inspection is what catches a bad gas connection or a venting mistake, apart from anything the state license covers.
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 how the place is laid out, then runs those numbers to find the heat loss on a cold night. A furnace that's too big will short cycle and wear out early. One that's too small will run constantly and still leave you cold when the temperature drops. This is a job for whoever installs it, not a number you can look up.
- How do I know it's time to replace my furnace?
- Age is one sign, but how the furnace is running matters just as much. Watch for uneven heat between rooms, a furnace that cycles on and off more than it used to, or a gas bill that keeps climbing without a reason. If a contractor has already told you the heat exchanger is cracked, that's not a repair, that's a replacement. Homes here need heat from October through April, with winter nights averaging 29°F, so a furnace that's struggling in the fall is not likely to hold up through the rest of the season.
- Is a high-efficiency furnace worth it?
- It depends on how long you plan to stay in the house and what your current furnace is costing you to run. Furnaces made after November 2015 have to hit at least 80 percent AFUE, so even a standard new furnace wastes less fuel than an old one. A high-efficiency model pushes past that baseline, which matters more here since homes need heat for 7 months of the year. A contractor can walk you through the actual models and what each one would cost installed, since that's not something to guess at.