HVAC Installation in Duncan, OK
A new system here will heat from November through April and cool from May through September every year. Tell us about the house, and a licensed contractor who covers Stephens County will get in touch.
Tell us about the job
It takes about a minute.
Eleven months of work a year in Duncan
A new system here only gets one month of rest. Winter nights average 31°F from December through February, and summer afternoons hit 93°F, so the unit you install has to handle both a hard freeze and real heat within the same year.
Heat runs November through April, six months, and cooling runs May through September, five months. That is eleven months of the two working, back to back, with barely a break between them. Storms are part of the picture too. Stephens County has seen 67 damaging wind events and 6 winter storms over the past ten years, and a quarter of Oklahoma households went at least a day without power in 2024. A new furnace or AC installed here needs to be sized and set up for what the county actually puts it through, not just a mild season somewhere else.
- 6 months
- November through April, your system heats
- 5 months
- May through September, it cools
- 31°F
- the average winter night it heats against
- 93°F
- the average summer afternoon it cools against
NOAA nClimDiv, 1991–2020 normals
Oklahoma requires HVAC contractors to hold a state license.
The Construction Industries Board is the state agency that issues the license and keeps the record on file. The license covers the contractor, not the job, so the same license that covers this installation covers every other job that contractor takes on.
For an installation like this one, that license is what stands behind the person doing the work in Stephens County. On top of that, most cities and counties require a permit from the local building office before a furnace, air conditioner or heat pump goes in, and an inspection once the work is done. That inspection is a separate check on this particular job, apart from the license the contractor already carries.
Source: Oklahoma State Legislature
- When should I replace my HVAC system?
- Replace it when repairs get frequent, the system is aging, or it can no longer keep up on the coldest or hottest days. Winters here average 31°F and summers average 93°F, so a system that struggles to keep up on those days is only going to fall further behind. If a contractor is called back to fix the same unit more than once a year, that is usually a sign replacement makes more sense than another repair.
- Should I replace my furnace and air conditioner at the same time?
- If both are old, yes, it is worth doing together. A furnace and air conditioner installed at the same time are matched to work with each other, and homes here need one or the other running 11 months of the year, so both units get heavy use. Replace them separately and the newer unit ends up paired with an older one it was not built to match. A contractor can look at the age and condition of each and tell you whether waiting on one makes sense.
- What happens during an HVAC installation?
- A contractor removes the old furnace and air conditioner, sets the new equipment in place, and connects it to the ductwork, gas or electric line, and condensate drain. They check the refrigerant charge, run the system through a full heating and cooling cycle, and confirm the thermostat is working with the new equipment. Replacing a furnace or air conditioner usually needs a permit from the local building office and an inspection once the work is done. That inspection confirms the installation was done to code before the system goes into regular use.