Tankless water heaters in New Hampshire
A tankless water heater heats water only when you use it, so you never run out and you stop paying to keep a tank hot. In New Hampshire, the cold incoming water is the thing to plan around.
Sizing starts with temperature rise
Tankless heaters are rated in gallons per minute at a given temperature rise. Winter groundwater here can be in the 40s, so heating it to about 120 degrees means a rise of 70 degrees or more. Size for your coldest month, not an average.
How much flow you need
Add up what might run at once: a shower is about 2 gallons per minute, a kitchen faucet about 1.5, a dishwasher or washer about 1 to 2. Two showers and a sink at once in January is a common sizing target.
Gas or electric
Gas and propane units handle high flow in cold climates well and are the usual choice for a whole house here. Whole-house electric tankless units need very large electrical service, so electric often makes more sense for a single bathroom or point of use.
Venting and efficiency
Condensing gas models are the most efficient and can vent through PVC out a side wall. Non-condensing models need stainless venting. Plan the location with the vent run in mind.
Well water and scale
Hard well water builds scale in the heat exchanger. Flush the unit with a descaling solution about once a year, and consider a softener; see well water treatment and our softener size calculator.
When a tank still makes sense
If you already have a newer tank, a small household or a tight budget, a high-efficiency tank or heat pump water heater can be the better value. Compare them in our water heater buying guide.
Common questions
Do tankless water heaters work in cold climates like New Hampshire?
Yes, when they are sized for the cold winter groundwater temperature. Undersizing is the usual cause of lukewarm showers.
How long do tankless water heaters last?
Often around 20 years with regular descaling, longer than most tank heaters.
Do tankless water heaters need maintenance?
Yes. Flush the heat exchanger about once a year, more often with hard well water.
Related: water filtration, water heater guide, well water treatment, plumbing.
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