Curbing Your Consumption:
Heating water can be a tankless job
By John Ford
Most homes have a tank of water in the basement heated by electricity,
oil, or gas. When hot water is needed somewhere in the house, cold
water is fed in one end of the tank, and hot water comes out the other
end. The water travels through the house, getting cooler as it moves.
What's wrong with this picture? Well, for starters, why store
hundreds of litres of water when you only need a litre to wash your
hands at the other end of the house? Why let the water sit all night
while you sleep or during the day when you're at work, leaking
heat into your basement? Does this sound inefficient? Why not heat the
water where and when it is needed.
Why not indeed. There are products available to do just this. Instead
of a tank of hot water, an in-line heater can be used to create hot
water as it is required. It is not only more efficient, but can be
more convenient as well. You never run out of hot water. Of course,
don't tell your teenager that or you might have to call for the
jaws of life to pry them out of the shower.
Water tanks allow minerals to collect and reduce efficiency and
effectiveness of heating elements. In-line heaters are flushed each
time they're used, so they have more advantages than just saving
energy. But there's a downside as well. Unlike a tank, the flow
through the heater is limited in order to ensure complete
heating. This effect can be minimised by sizing the unit
correctly. Gas is a better choice for a central unit because it can
deliver much more heat and a better flow rate. A central in-line
heater suffers from the same pipe heat loss as water travels through
the house just like a tank system. Insulating hot water pipes reduces
those losses.
There are also small in-line units available to locate right where
they're needed. Big jobs require 240v units to deliver enough
heat, so the cost of wiring needs to be considered. I have used an
in-line shower heater in England, and they work extremely well, but
they benefit from 240v house voltage compared to our 120v, so no
special wiring is required.
Without replacing your tank, you can save by shutting off the breaker,
or turning down the thermostat when the tank is not in use. You should
already be in the habit of doing that when you leave for a few days
anyway.
Ask the Miser
If you would like to see answers here to your questions about energy
consumption, email them to
questions@oea.dyndns.org
John Ford is a technology consultant, and owner of a small energy
conservation business.