The Watts instructions say that it is not compatible with water heaters with a heat trap. But you can find out if your water heater has a heat trap on the websites of most water heater manufacturers. That’s what I did before buying my Watts almost 4 years ago. I have been totally satisfied with my Watts pump. I have a relatively small house, but the water heater is at one end while the master bath is at the other end. The thermostatic valve is mounted under the master bath’s sink. I get instant warm water (measured at 90°F) when I turn on the hot faucet; it takes about 8 seconds to get cold water out of the cold faucet. The pump is very quiet, it’s easy to program its rudimentary timer, and I recommend it. The installation was easy, both at the water heater and under the master bath sink-very basic plumbing, and all parts are included in the kit.