Water heater buying guide: tank, tankless or heat pump

Most water heaters get replaced in a hurry, the day the old one leaks. Knowing your options ahead of time can save real money over the next 10 to 20 years.

Tank water heaters

The familiar choice: a 40 to 80 gallon tank kept hot all the time. Lowest upfront cost and simple to replace like for like. Size by the first-hour rating, not just gallons: a family of four usually needs about 60 to 70 gallons of first-hour delivery.

Tankless (on-demand)

Heats water only as you use it, so it never runs out and takes almost no floor space. Size by flow rate: add up the fixtures that run at the same time (a shower is about 2 gallons per minute) and account for cold New Hampshire incoming water, which means a bigger temperature rise. Gas units need proper venting; electric units need a lot of amperage.

Heat pump water heaters

A tank water heater with a small heat pump on top that pulls heat from the surrounding air: often 2 to 3 times as efficient as an electric tank. It needs room around it (usually about 700 cubic feet) and cools and dries the space, which is a bonus in a damp basement. Utility and federal incentives often apply.

Which is right?

• Replacing an electric tank: look hard at a heat pump model.
• Gas or propane house, small space: tankless.
• Lowest cost today, simple swap: a like-for-like tank.

The water heater sizing calculator sizes each type for your household.

Hard water and wells

Hard or iron-rich well water shortens water heater life and clogs tankless heat exchangers. A softener or filter ahead of the heater protects it. See water filtration.

Common questions

What size water heater for a family of 4?

A tank with a first-hour rating of about 60 to 70 gallons, often a 50 gallon gas or 65 to 80 gallon heat pump tank.

Is a tankless water heater worth it?

In gas or propane homes with space constraints, often yes. In cold climates it must be sized for a large temperature rise.

Do heat pump water heaters work in New Hampshire?

Yes, installed in a basement or utility space with enough air around them; they also dehumidify the space.