Letters: March/April 2011

March/April 2011
A version of this article appears in the March/April 2011 issue of Home Energy Magazine.
Click here to read more letters.

Combustion Appliance Zone


Signs of a sick water heater. (Pure Energy)

I saw your recent article on combustion safety (“Combustion Appliance Testing: Why, How, When?” Nov/Dec ’10, p. 38). I think I have a problem and was wondering if you would give any suggestion. I have a ranch-style home. In the basement, my furnace and water heater shared the same exhaust. A direct-vent furnace was installed, and a 4-inch liner for the orphaned water heater. If a dryer, two bathroom fans, and one kitchen fan are turned on, the combustion appliance zone (CAZ) is at about -8 Pa. The BPI guy who had checked on the house suggested a power-vented water heater or that I remove all the fans from the house. Unfortunately, the water heater is only three years old. What else can I try to correct the problem?


via e-mail


Author Tamasin Sterner replies:

If the CAZ is depressurized more than the CAZ depressurization limits for the appliance you have (which it is, according to the info you have provided me), and you can’t figure out why it is under so much negative pressure, then BPI requires one of three options: Have some pressure relief in the CAZ with respect to the outdoors (make a hole to the outside near the water heater); modify the exhaust appliances (typically move the dryer out of the CAZ); or supply combustion air directly to the water heater to assist draft. If it were my home, I’d remove the water heater and put in a power-vented water heater or an electric water heater. But first I’d attempt to figure out why my CAZ is under so much negative pressure.

The CAZ negative pressure may be due to air leaks through the attic floor into the living space. Sealing these air leaks should be your highest priority for energy savings, comfort, and building durability. Sealing these leaks may make the CAZ less negative with reference to the outdoors, and if this brings the CAZ depressurization into an acceptable limit, you should be safe. Your BPI BA Professional is required to do an attic zonal pressure test. I suggest you ask for the diagnostic test result.

Cheating Not Such a Secret Anymore

Great article: “Cheating—The Insulation Industry’s Dirty Secret” (Nov/Dec ’00, p. 24) by Michael Uniacke. I have been involved in the building industry for over 30 years. There is no question that the insulation contractors and installers have gotten and are getting away with murder.

Many inspectors believe, “If it’s not a safety issue, it’s not my problem.” However, times are changing and building departments are now finding that they are accountable for enforcement of the energy codes. We all need to make sure the customers are getting what they are paying for. Our collective efforts will save millions of dollars in energy costs if we work together and do our jobs.

Kent L. Partridge
Building Official
Eagle Mountain City, Utah

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