Efficient Hot Water With Less Noise
Seeking a quiet heat pump water heater? Noise may be part of the bargain.
I’m considering installing a heat-pump water heater (HPWH) to replace my electric-resistance water tank. Unfortunately, I see regular online reviews of common models complaining about premature failures and noise from the heat pump’s refrigeration unit. Are there quiet, reliable models out there? I plan to put the water heater in my conditioned crawlspace, which measures about 1200 sq. ft.
— Eli; Via the GBA forum
Jake Staub, Chief Technical Officer at Ripcord Engineering, Replies
The short answer is no. “Packaged” HPWHs (those with compressors above the tank) that are installed inside the conditioned envelope are perceived as “loud” by most people.
My company, Ripcord, has found that approximately 25 dBA is a tolerable level of noise for most people. The “A” in dBA signifies a weighted decibel, as perceived by humans. According to manufacturer data, the least “loud” packaged HPWH is a 42-dBA unit by LG. Most others operate at around 60 dBA.
So for a “quiet” installation, acoustic isolation for the water heater must compensate for unit noise. Simply put, you need to deliberately separate a packaged HPWH from the living area. Make sure the acoustic separation complies with code and follows manufacturer’s instructions to ensure safety, proper operation, and warranty coverage.
To reduce the heat-pump water heater noise level in crawlspaces that connect to living spaces, install a weatherstripped door and seal air leaks between the crawlspace and living space. Then follow code requirements for unvented crawlspaces.
For packaged HPWHs in mechanical closets, follow manufacturer instructions for ducted installations. A tight-sealing door and a sufficiently air-sealed mechanical space will reduce sound transmission. Silencers, produced by manufacturers like Zehnder and Fantech, are recommended for intake and exhaust ductwork.
Another quiet way to make hot water is with a split HPWH like the SanCO2, which has a separate compressor installed outdoors. Split HPWHs cost more than packaged HPWHs but can be cost-effective compared to installing a packaged HPWH with a complex plan for acoustic separation.
— Jake Staub; Chief Technical Officer at Ripcord Engineering
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