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A contractor quoting furnace repair here looks at the burner assembly and the ignition system before anything else, because those are the components that cycle every time the heat comes on. Homes in Hillsborough County, NH run heat about eight months a year, from October through May. By the time spring arrives, the heat exchanger has expanded and contracted through months of hard use, and a crack or a degraded seal that was minor in October can be a real problem by May. A failed igniter or a cracked heat exchanger is not a freak event in a county that runs its furnaces this hard; it is what accumulated cycling produces.
Ductwork and heat exchangers in houses like these have been working for a long time before the call for repair ever gets made. Half the homes in Hillsborough County, New Hampshire were built in 1978 or earlier (2020-2024 ACS 5-year). A contractor opening a furnace in this county finds components that have cycled through a serious number of heating seasons, and the condition of the heat exchanger, the burner assembly, and the flue connections is what decides whether the repair is a straightforward parts swap or something the homeowner needs to weigh against replacement. Parts availability is the other variable: not every component a furnace of this vintage takes is still in regular production.
The Parts of a Furnace a Contractor Checks First
The furnace cabinet sits in the basement, utility room, or crawl space and is the core of the system. Inside it, the heat exchanger takes the brunt of every heating cycle, and cracks or blockages there are what a contractor looks for when a furnace runs poorly or shuts down unexpectedly. The burner assembly and igniter sit just below it and are frequent starting points when the system fails to light.
The blower motor and fan wheel live in the lower half of the cabinet and push conditioned air into the supply ducts. The flue pipe runs from the cabinet up and out of the house, and a blocked or corroded flue shows up quickly as a safety lockout. The control board ties all of it together, and a contractor reads its fault codes early in the diagnosis.
The drawing shows a representative furnace layout, and a licensed contractor determines which components apply to your specific system and situation.
Find a contractor in Hillsborough CountyHillsborough County, by the numbers
251 severe weather events were recorded in Hillsborough County, New Hampshire between 2015 and 2024.
NOAA National Centers for Environmental Information, Storm Events Database, bulk CSV export, events 2015-01-01 through 2024-12-31.Half the homes in Hillsborough County, New Hampshire were built in 1978 or earlier (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesHillsborough County, New Hampshire holds 177,734 housing units (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesOwners occupy 67.4% of the occupied homes in Hillsborough County, New Hampshire (2020-2024 ACS 5-year).
U.S. Census Bureau, 2020-2024 American Community Survey 5-Year EstimatesCodes & Standards for Furnace Repair in Hillsborough County, New Hampshire6 rules & citations
What HVAC Repair Looks Like in Hillsborough County
Non-weatherized gas furnaces manufactured on or after November 19, 2015 must reach 80.0 percent AFUE.
Non-weatherized oil-fired furnaces manufactured on or after November 19, 2015 must reach 83.0 percent AFUE.
Mobile home gas furnaces manufactured on or after November 19, 2015 must reach 80.0 percent AFUE.
Non-weatherized gas furnaces manufactured on or after December 18, 2028 must reach 95.0 percent AFUE, up from the 80.0 percent minimum that applies to units manufactured before that date.
Licensing and Legal Requirements in Hillsborough County, New Hampshire
New Hampshire's mechanical licensing board issues nine credentials — hearth system, four fuel gas endorsements, domestic appliance technician, and master, journeyman and apprentice plumber — and a licensee may not work outside the specialty their licence names. None of the nine is an HVAC licence.
New Hampshire does not license HVAC as a trade, and says so where it matters: the plumbing licence expressly does not reach a person installing heating, cooling, air conditioning or domestic water heating systems, whether solar, oil, gas or electric. The gas piping on a gas-fired system is a separate matter and needs a fuel gas fitter licence.
Severe Weather Events in Hillsborough County
Extreme weather puts real stress on furnace components, from heat exchangers to ignition systems, and that stress accumulates over time. How hard the weather works a furnace in Hillsborough County shapes what breaks, when it breaks, and what a repair here looks like.
251 severe weather events, 2015–2024. Source: NOAA National Centers for Environmental Information, Storm Events Database.