People often think they are wasting just their time waiting for hot water. Actually, they are also wasting a substantial amount of energy and water down the drain while they are waiting. In many parts of the country, fresh water is a precious resource.
If you are remodeling, run a larger hot water supply pipe directly to the bathroom. Existing hot water plumbing can sometime snake throughout the house before reaching a bathroom that is not actually very far from the water heater. A new pipe can also improve efficiency because you can wrap it with heavy insulation.
Another option is installing a special rapid-hot-water kit. The three basic types are a demand system, a timer system and a temperature controlled system. All three types eliminate any wasted water. The demand systems will still require a short delay (perhaps 10-20 seconds) to get the hot water to the faucet and require electrical connections. The timer system totally eliminates the wait during the timed cycles, but it consumes more energy and requires electrical connections.
Post construction units use a crossover valve between the hot and cold water supply pipes under the bathroom sink. When you want hot water, hot water from the water heater moves through the existing hot water pipes.
Instead of opening your faucet and allowing the cooled water to be wasted down the drain, it flows through the crossover valve into the cold pipe and returns to the water heater for reheating.
A demand system starts a high-volume pump when you push a button near the pump, so it runs only when you actually need hot water (only at that sink). Remote buttons can be installed in other bathrooms, laundry room, etc, but require extensive wiring.
A timer system runs a low-volume pump when the timer tells it to, usually in the morning. The pump runs only during the “on-time” setting on the timer, but only provides instant hot water when the pump is running.
Temperature controlled systems only allow hot water to circulate when the water temperature drops below the adjustable temperature setting (which provides instant hot water whenever you need it), is all mechanical and requires no electrical connections for an easy installation.
One such temperature controlled system that is a simple DIY installation is the Hot Water Lobster Instant Hot Water Valve.
The following companies offer water recirculation kits: ACT, gothotwater.com; Grundfos Pumps, grundfos.com; Hot Water Lobster Instant Hot Water Valve, hotwaterlobster.com; Laing Thermotech, instanthotwaterpump.com; and Temtrol Delta T, redytemp.com.