HVAC Installation in Dover, NH
A new system here will heat from October through May and cool from July through August every year. Tell us about the house, and a licensed contractor who covers Strafford County will get in touch.
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Dover asks a lot of a heating and cooling system
Winter nights here average 16°F from December through February, and homes need heat from October through May. That's 8 months of the year the furnace or heat pump has to keep up. Summer is shorter but real too, with afternoons averaging 79°F through July and August. Put the two together and a system here runs 10 months out of the year.
Nearly 43% of homes in the area heat with fuel oil, so a lot of what gets installed has to work alongside an oil-fired setup or replace one outright. Power is part of the picture too. In New Hampshire, 22% of households went at least 24 hours without power in 2024, and the area has logged 44 winter storms and 43 damaging wind events over the past ten years. A new system should be sized and installed with that kind of season in mind.
- 8 months
- October through May, your system heats
- 2 months
- July through August, it cools
- 16°F
- the average winter night it heats against
- 79°F
- the average summer afternoon it cools against
NOAA nClimDiv, 1991–2020 normals
New Hampshire has no state license for HVAC contractors.
There is no state board behind an HVAC contractor here, and no state list to check them against. New Hampshire does not license or register HVAC contractors at all, so there is no state credential standing between you and whoever you hire.
For a system installation, the protection that does exist comes from the permit. Putting in a new furnace, air conditioner or heat pump needs a permit from the local building office in most cities and towns, and an inspection once the work is done. That inspection is what checks the gas connections and the wiring, the parts of the job where a mistake actually matters. It is not a license, and it does not tell you anything about the contractor before you hire them. It is what New Hampshire has in place of one.
Source: New Hampshire General Court
- When should I replace my HVAC system?
- Replace it when repairs are becoming frequent, when it can't keep up on the coldest nights, or when it's old enough that a breakdown could leave you without heat for days. A furnace that needs a new heat exchanger or a repeatedly failing igniter is usually done. Age matters too. If something major fails on an old unit, putting money into it often doesn't make sense when the whole system is near the end anyway. Homes here need heat from October through May, so a furnace that's on its way out is worth replacing before it fails on you during those months.
- Should I replace my furnace and air conditioner at the same time?
- If both are old, replacing them together is worth considering, but it depends on the condition of each one. A furnace and air conditioner installed at different times can still work fine together as long as both are sized right and in decent shape. Where it makes more sense to pair them is when one has already failed and the other is close behind. A contractor can look at the age and condition of both and tell you whether replacing one now and planning for the other later makes sense, or whether doing both at once is the better move for your house.
- What happens during an HVAC installation?
- A contractor removes the old furnace, air conditioner or heat pump and sets the new equipment in place, then connects it to the ductwork, gas or electric line, and condensate drain. The new system gets wired to the thermostat and tested through a full cycle to check airflow, temperature rise, and refrigerant charge if it's an air conditioner or heat pump. Most cities and counties require a permit for this work and an inspection once it's done. That inspection is there to confirm the installation meets code, including venting and clearances that matter for safety.