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© 2004-2017 John Ford

 
Become an Educated Energy Consumer    OttawaEnergyAudit     Friday 15 December 2017
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Published Columns: November 2004
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.