I thought that 4 gals per minute meant up to 4 gals per minute. It mean at least 4 gallons a minute. If you turn down the hot water, The water heater shut off. If you have water saving faucets it wont draw enough water to turn the system on. It's all or nothing. You can't add cold water to the shower, It shut the water heater off. The book says if you have this problem. Buy one with lower gals per minute. After I already bought and installed this one. They must think we are all made of money. I do not recommend this unit. You can not fine tune the temp.
