Issue # 24: DHW Systems
ISSN 1703-5597
February 4, 2004

Issue #24 DHW Systems

  1. The Basics: Glossary, Household Use, How They Work
  2. Planning: Sizing, Operating Costs, Venting Options
  3. Common Products: Tank Heaters, On-Demand, Combo
  4. Unique Products: Stoves, Solar, Heat Pump, D’MAND
  5. Issues: Water Quality, Treatment, Energy Efficiency
  6. Safety: Combustion Gases, FVIR, Safety Tips
  7. Maintenance: Troubleshooting, Maintaining, Replacing

1. The Basics: Glossary, Household Use, How They Work

Water Glossary
So you think an acre-foot is what you get from stubbing your toe (groan). This easy-to-use glossary from Nevada Division of Water Resources Department of Conservation and Natural Resources, gives you explanations of common terms used in the water industry.

Household Water Use
If you want to know how much hot and cold water is used in different household applications, this Energy Source Builder article has graphs and charts showing the averages for each.

How Water Heaters Work
Popular Mechanics offers you an article with drawings showing you how different water heaters work. Included are electric & gas tank-type, tankless, and instantaneous systems.

2. Planning: Sizing, Cost Comparisons, Venting Options

Tank Sizing Calculator
Here is an online calculator from Bradford White to help you decide how big your tank should be (capacity) and what your first-hour rating is for sizing the energy input requirement.

Fuel Cost Comparisons
This article from BC Hydro shows the relative space and water heating costs for gas furnaces of various efficiencies and different electric systems.

Venting Options
The Terasen Gas Web site has a brief description of four different methods of venting gas heaters. It covers vertical, through-the wall, direct vent, and power vented systems.

3. Common Products: Tank Heaters, On-Demand, Combo

Efficient Gas & Electric Tanks
Power Smart explains gas and electric high efficiency water heaters. To view the electric system click on the “High Efficiency Electric Water Heating” link on the right sidebar.

Demand Systems: Tankless Or Instantaneous
Systems that provide hot water on demand are covered in this brief from the US Department of Energy. Keep in mind all costs mentioned here are in US dollars.

Combo: DHW Plus Space Heating (PDF FILE)
In energy efficient buildings a water heater can possibly provide both the DHW and space heating needs. This Building Science Corporation Report gives a good overview of these systems.

4. Unique Products: Stoves, Solar, Heat Pump, D’MAND

Hot Water From Wood Stoves
This article from Hearth Net site explains (with diagram) how to design a system for getting free hot water from a wood stove using internal or external heat exchangers.

Solar Water Heating
If you use a lot of hot water, or have high fuel costs, solar may provide at least part of your needs. Advanced Buildings shows you where and how a system works, along with costs.

Heat Pump Water Heaters
The US DOE has a detailed overview of heat pump water heaters including how they work, where to use them, design considerations, savings and maintenance issues.

Hot Water On Demand System
For those times when you want water quickly, especially to distant fixtures, this innovative D’MAND hot water recirculation system as explained by NAHB might be just what you need.

5. Issues: Water Quality, Treatment, Energy Efficiency

Safe Drinking Water FAQ
With water quality being of increasing concern to many consumers this FAQ from Lenntech could be valuable for answering some common drinking water questions.

Water Treatment
To help you sort through the various water treatment methods check out these CMHC articles that include overviews of reverse osmosis, UV, distillers, filters and softeners.

Energy Efficient Water Heating
If you or your homeowners want to reduce hot water heating costs this fact sheet from DOE has info on lowering usage, increasing efficiency, and links to more resources.

6. Safety: Combustion Gases, FVIR, Safety Tips

Combustion Gases In Your Home
Carbon Monoxide poisoning can be a concern if fuel fired DHW tanks are not selected and installed based on considering the House as a system, as CMHC explains.

FVIR: Flammable Vapour Ignition Resistant
New standards call for gas DHW systems to be equipped with FVIR. This consumer information from GAMA gives some background and answers common questions about FVIR.

Safety Tips
This Water Heater Rescue site has information on a number of safety issues such as vents, dielectric connectors, T & P valves, earthquakes straps, controls, hatch and pedestal.

7. Maintenance: Troubleshooting, Maintaining, Replacing

Troubleshooting Chart
To help you or your homeowners troubleshoot problems the Plumbing World site has a couple of very simple charts listing various problems along with possible causes and solutions.

Maintaining A Water Heater
Water heaters do require maintenance and Lowe’s has a very simple online tutorial showing how to check the pressure relief valve and steps to follow for flushing the tank.

Replacing A Water Heater
The site offers this tutorial with drawings showing how to remove and replace natural gas, LP and electric water heaters.

Dittie For Today: On Experience
Learn from the mistakes of others. You can't live long enough to make them all yourself.

 © Copyright 2004               Ken Farrish               All Rights Reserved