Mini Split 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.
Tell us about the job
It takes about a minute.
What Dover winters ask of a mini-split
Dover needs heat eight months a year, October through May, and winter nights average 16°F. A mini-split doing that job has to hold its output on the coldest nights, not just the mild ones in between. Summer only asks for two months of cooling, with afternoons averaging 79°F, so the unit spends most of its life heating, not cooling.
Any mini-split installed new has to meet the federal minimum for a split-system heat pump, 14.3 SEER2 for cooling and 7.5 HSPF2 for heating. A lot of Dover homes heat with fuel oil, and a mini-split sized for the winter here gives a home a second way to hold heat if the oil system falls behind or the power goes out. Strafford County has seen 44 winter storms and 43 damaging wind events over the past ten years, and statewide, 22% of households lost power for at least a day in 2024.
- 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 this job and no state record of who did it. New Hampshire does not test HVAC contractors or keep a list of who is registered to do this work, so nothing about a contractor's standing in this trade is on file anywhere in the state.
What protects you here is local. A mini-split installation in most cities and towns needs a permit from the building office, and an inspection once the work is done that checks the wiring and the mounting are sound. That permit and that inspection are the record this job leaves behind, not a license.
Source: New Hampshire General Court
- Is a mini split worth it?
- For most homes it comes down to what you're heating or cooling and what's there now. A mini split gives you heat and cooling from the same unit, with no ductwork to lose energy through. Here winters get down to 16°F on average and homes need heat from October through May, so the mini split you choose has to be rated to work at that cold, not every model is. If your home currently heats with fuel oil, which is common in this area, a mini split can cover some or all of that load depending on the house. A contractor can look at your specific rooms and tell you what makes sense.
- How many rooms can a mini split cover?
- A single outdoor unit can run more than one indoor head, so it depends on how many heads are installed, not on the outdoor unit alone. A single-zone system covers one room or open area. A multi-zone system runs several indoor heads off one outdoor condenser, with each head handling its own room. How many rooms one setup can carry depends on the size of the outdoor unit and the size of each room. A contractor can size this out room by room for your house.
- Can a mini split heat a whole house?
- It can, but only if it's designed to, room by room. A multi-zone mini split with enough indoor heads placed through the house can heat the whole thing, the same way a furnace with enough ducts reaches every room. What matters here is the cold. Winter nights average 16°F from December through February, and homes in this area need heat from October through May, eight months of the year, so the system has to be sized and rated to keep up on the coldest nights, not just the mild ones. A contractor can work out how many heads your house needs and whether the unit you're looking at is rated for that cold.