Ed Lau bought his 1956 ranch-style home located in Sunnyvale, California in 2012. The home had a gas furnace and in 2015, he put in central air conditioning. The air conditioner was single-stage and would turn on and off frequently, which made it noisy and not energy efficient.

By 2022, Ed wanted to replace both the gas furnace and the AC with a heat pump to improve the comfort and sustainability of his home. He found that he qualified for ~$3,500 in rebates from his utility and BayRen, and he could claim $2,000 off his federal taxes for installing a heat pump.

He worked with an HVAC company to design a Mitsubishi heat pump system that used the existing ducts throughout the majority of the house. “In our home office and master bedroom, we wanted better control of the climate,” Ed says. They choose a wall-mounted mini-split for the home office and a ceiling cassette mini-split for the master bedroom, giving them precise temperature control.

The three branches of the system were all powered by a 48,000 BTU compressor which sat on the outside of the home. “I have a suspicion that the installer oversized it,” Ed says, a common problem in the industry. If he could design the system again, he would consider having three smaller compressors, one for each branch of the system, to make the heat pumps run more efficiently.

Regardless of the imperfect design, Ed says the heat pump is super quiet and the temperatures throughout his home are more comfortable than they were with his old gas furnace and AC. “I also feel better that I’m not releasing noxious fumes by burning gas,” Ed says.