Installing an on demand hot water system varies depending upon the make and model. Some, such as the system diagramed below, are relatively simple and involve installing a pump underneath a sink. Other systems may require additional plumbing. Read the directions carefully before installing an on demand hot water system. Consult your salesperson about installation before making your purchase. When in doubt, hire a professional plumber.
Basic installation instructions – Demand Type Pump System
System components are often pre-wired and pre-attached. Installation is a simple matter of connecting the water system between the hot and the cold water supply, attaching the push button to the low voltage wire provided, and then plugging into a 110 Volt standard outlet. The whole system can be installed in less than two hours and does not require major modifications to the plumbing system. The only tools needed are an adjustable wrench and a screwdriver.
NAHB Research Center