Why should I heat both the hot and cold water supply?


The reason for recovering heat to both the hot water and cold water lines is fairly simple. When more water is taking heat away from the draining hot water, more heat is captured (which means the device is operating more efficiently).

Why would you want to heat your cold water supply?

This is a reasonable question. The benefit of heating the cold water is that when people are using hot water to wash their hands or take a shower, they mix the hot water with cold water to cool the hot water down to a comfortable temperature. If the "cold" water is warm they require less hot water to reach the comfortable temperature. So heating the cold water means less hot water is used, while improving the efficiency of the in-line heat recovery device at the same time!