Ways to Save Money on Hot Water

• Drain Water Heat Recovery
  • Can pay for itself in 0.4 to 7 years, according to several sources (try a Google search for Drain Water Heat Recovery.
  • Cost $300-$1000 including a plumber's visit; 1-2 hours in new construction, 4-6 hours in a remodel.
  • Commercial systems can pay off the fastest (e.g., dishwasher heaters).
  • "$40 billion goes down the drain in North America each year."
  • 90% of the energy used to heat water in a home can be washed out to the sewer.
  • Put your hand on your plumbing drainpipe in the basement while someone is taking a shower, and you'll instantly understand the opportunity.
  • If tepid is 100 degrees and hot is 110 degrees, then the preheating of cold water from a ground temperature of maybe 50 degrees up to tepid is 5x more expensive than heating from tepid to hot. So mere pre-heating offers plenty of opportunity to save.
  • Technology: A normal vertical drain/waste pipe, but made of copper and surrounded by a spiral of copper tube for heat transfer. Waste water naturally flows in a thin sheet down along the inside of a pipe, which makes the embodied heat in the graywater from a shower or dishwasher available for transfer through the copper pipe walls, and the copper tubing with the potable cold water suck does the heat transfer.
• Insulate your Hot Water pipes and even the cold water pipes as they get close to your water heater. Then you can lower the temperature setting on the heater and get the same temperature water at the fixtures. An inexpensive, Do It Yourself project.
• Insulate your Hot Water tank to R-24 or better. Put your hand on your water heater: if it's warm, you should do this. It reduces standby heat losses by 25% to 45%, and you should save 4% to 9% on your water heating costs for a blanket, and another 4-9% for a bottom board. Payoff time: about a year. Cost: ~$20 for materials (insulating blanket to wrap it, rigid foam board insulation to put under it; if your heater is electric, you can safely "do it yourself").
• Add heat traps so heat doesn't dissipate out of your tank through the piping. $30 plus installation, cheapest when the tank is new. Saves $15-$30/year.