Water Heater Installation in Portsmouth, NH
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What a new water heater in Rockingham County has to handle
Winter nights here average 18°F from December through February, and the water main feeding the tank runs cold right along with the air. Homes in this county need heat from October through May, eight months a year, and the water heater is drawing cold water through most of that same stretch.
Power is part of the picture too. Statewide, 22% of households went at least 24 hours without power in 2024, and the county has logged 66 winter storms and 103 damaging wind events over the last ten years. That is worth weighing when deciding what kind of unit goes in.
The federal minimum efficiency for storage water heaters is not one number. It is set by a formula tied to the tank's rated volume, applied separately across four draw patterns, so two tanks of the same type but different sizes have to meet different minimums. Sizing the tank correctly is part of meeting that standard, not a separate step from it.
- 18°F
- the average winter night, and colder incoming water means longer heating
- 8 months
- October through May, the months homes here need heat
- 22%
- of New Hampshire households lost power for a day or more in 2024, and a heater with an electric element or electric ignition stops without it
NOAA nClimDiv, 1991–2020 normals
- How do I know it's time to replace my water heater?
- Water pooling at the base of the tank means it's time. That's the tank itself failing, not a loose fitting, and it won't seal back up. Rusty water from the hot tap, a tank that's rumbling or popping, or hot water that runs out faster than it used to are all signs the tank is wearing out inside. If yours is old and starting to act up, get it looked at before it fails outright. A tank that fails on a night near 18 degrees isn't just a mess, it can mean going without hot water until it's replaced.
- Should I switch to a tankless water heater?
- It depends on what you want out of your hot water, not on there being a right answer for everyone. A tankless unit heats water as it's used instead of storing a tank of it, so you don't run out partway through back to back showers. It also takes up a lot less space than a tank. Against that, a tankless unit needs the right gas line and venting for its size, and if you already have a tank system, switching means changing more than just the water heater. A contractor can tell you what your house would need to make the switch.
- What changes when you install a tankless water heater?
- The biggest change is that a tankless unit makes hot water on demand instead of holding a tankful ready to go. That means it can supply hot water without running out, but it also has a limit on how much it can heat at once, which matters if more than one shower or appliance runs at the same time. The gas line sizing and venting are usually different from what a tank used, so those often need to be redone as part of the install. It also mounts on the wall rather than sitting on the floor, so where it goes in the house changes too.