Waltham, MA: the heat pump payback math

Waltham technically pencils out, but only past the point the equipment would need replacing anyway. Against a like-for-like gas furnace and AC swap, going electric costs $3,500 more up front here (already netting out a $2,000 tax credit). Lower bills claw that back: about $101 saved annually, for a payback of roughly 34.5 years. That's a technicality, not a recommendation, for anyone actually living in Waltham.

Waltham's weather, in the numbers that matter

Degree days tell the story here: Waltham racks up 5633 heating degree days each year (base 65°F), and summers add a moderate cooling load, with 703 cooling degree days on the cooling side. Sizing runs off the design temperature, not the average day: 10°F here (record low 0°F), which works out to a seasonal COP of 2.94 for the cold-climate class of unit this climate calls for. Waltham needs the cold-climate class of unit: past a 25°F design temperature a standard heat pump falls back on resistance backup often enough to eat the savings. These numbers come from LAURENCE G HANSCOM FLD APT, the closest NOAA station, 6.1 miles out.

Waltham's running-cost comparison, in dollars

Electricity use for heating alone comes out to about 4,852 kWh a year on the 2000-square-foot reference house; folding in cooling puts the electric bill near $1,643 a year. That compares with roughly 59 Mcf a year of gas at Waltham's 25.06 per-Mcf rate — about $1,745 a year — against a local electricity rate of 30.15¢/kWh. Buy it outright, not incrementally, and payback stretches to 133.1 years; over 15 years the net position sits $1,979 behind.

Electric resistance heat in Waltham, compared

Not every home in Waltham has gas service. Compared with baseboard or electric-furnace resistance heat, the numbers shift in the heat pump’s favor. About $2,932 a year comes back this way, enough that the 2.7-year payback clears the $8,000 premium comfortably within the equipment's life.

Where Waltham ranks in this dataset

Waltham lands at position 333 out of 3206 cities on heating severity (coldest is 1), and 599 out of 3206 by population size (biggest is 1). That's the coldest third of the dataset, where climate does most of the work behind this figure.

What to do with this number in Waltham

Waltham, Massachusetts is home to about 65,849 people, and the figures above are the same ones a local HVAC contractor uses to size and quote a system — this site doesn't guess where a real quote would land, it just tells you whether it's worth asking for one. In Waltham, nothing is lost by holding off until the current equipment genuinely fails.

Line up a few local HVAC quotes before you decide.

Where Waltham's figure comes from

The methodology guide walks through exactly how Waltham's 2.94 seasonal COP and the rest of this page's numbers get built. At a 10°F design temperature, Waltham sits in cold-climate territory; the guide to that class of unit explains why.