About Home Inspection
Home Inspection Legislation

Kaplan Graduate Benefits

Inspector Tech Support

Inspection Report Newsletter

Inspection Tips Free E-Newsletter

Inspection Industry Events
Articles & Press Releases
Errors & Omissions Insurance
Classified Ads / Help Wanted
Free Online Advertising
Realtor Resources
Inspector's Resource Guide
Site Map


Kaplan ITA's Monthly Inspection Tips - Free Electronic Newsletter

March, 2005
On-Demand Water Heaters
Issue #35

This month I would like to discuss on-demand (also known as instantaneous or tankless) water heaters.

There are basically two types of water heaters, storage type and tankless. Storage water heaters are still the most popular in the United States due to the higher initial cost of tankless and the flow demand limitations of some units.

Storage type heaters keep water at a 120-140 degree constant temperature ready to use. This is a waste of fuel and can represent 10-20% of energy costs. In a tankless heater water is only heated when there is demand (flow). Once activated the unit continues to heat water as long as there is demand. The elimination of continuous storage of heated water can substantially reduce standby heat loss thus saving energy. Since demand water heating required more BTU's when operating than standby you will notice units designed to replace a 40-gallon storage type heater (usually about 40-50K BTU) will be about 125,000 BTU's.

Tankless heaters are easily installed and occupy much less space than a storage type. In high flow conditions (multiple bathrooms) several units may be necessary strategically placed near bathroom groups or centrally located and connected in series to provide high volume heated water.

Illustration from the new Code Check HVAC 2nd Edition, available soon from Kaplan.
Pre-Order yours NOW for only $17.95!

Mark Your Calendar for "Safe and Sound", Kaplan's East Coast Regional Seminar.
May 21-22, 2005 in Miami, FL.
Click Here for Details

Nearly every one of these units I have seen (whether electric or fuel gas) is clearly labeled with minimum clearances to combustibles. Of course the clearances are much less for electric models.

Many of these units are factory supplied with overheat sensors to auto shutoff. However, the IRC requires any equipment used for water heating or hot water storage to be equipped with pressure and temperature relief. Most units have tappings specific for this valve. Some units have anti-freeze protection wherein the unit turns on intermittently if the temperature drops below freezing.

I have included an illustration of a typical fuel gas fired tankless water heater for further demonstration.

We'll talk next month,

Michael Casey
Kaplan Professional Schools

Now You're Ready For Business!™


Home inspection training schools nationwide

Advertising Opportunities Available

A Kaplan Professional Company.   © 2004, DF Institute, Inc. All rights reserved. Call Toll-Free: 1-888-323-9235