A heat pump that’s too big raises costs and reduces comfort. Here are some tips for sizing your system right.

Heat pumps may be a near-magical kind of technology, but they’re not one-size-fits-all. In fact, selecting the wrong size can have miserable consequences for your wallet, your comfort — even your health.

Unfortunately, installers often propose systems two or even three times bigger than needed, according to Mike Simons, training and development manager at Abode Energy Management, a home-efficiency and decarbonization consultancy. Oversizing can make heat-pump projects ​“wildly unaffordable,” Simons told Canary Media, occasionally even leading to instances in which ​“what should cost $15,000 is now $40,000.”