... on Solar Water Heating ...
Introduction & Resources |
Design & Installation Recommendations |
Heat Pipe Facts |
Save Money on Hot Water |
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
- Add heat traps so heat doesn't dissipate out of your tank through
the piping. $30 plus installation, cheapest when the tank is new.
Copyright © 2000-2007,
Thomas C. Veatch. All rights reserved.
Modified: November 26, 2007