World of Water Heaters Rapidly Changing

There's also a local driving force that may soon be causing a bit of a ruckus in the world of water heaters. That driving force is the Fort Collins Housing Performance Study, which is being released in September -- about nine months later than previously mentioned by this writer.

Some facts and discussion about all three of those driving forces are listed below.

Water heaters and fires

The relatively open flame in a water heater can sometimes cause a house f ire if' it comes in contact with flammable vapors that are spilled in the room where the water heater is located. During an average year in the early 1990s, the Energy Design Update reported (April 20M) that "gas-fired water heaters ignited flammable vapors which cased nearly 2,(x)0 fires, 320 injuries, 20 deaths and more than $26 million in property damage."

In response to this potential problem, the Consumer Product Safety Commission began pushing for enhanced safety protection. Water heater manufacturers agreed, forming a consortium in 1995 to research solutions. By late 1999, the American Water Heater Company introduced a model designed to combat the problem.

Jell-Mahoney, district sales manager for Rheem Water Heaters based in Castle Rock, told the HBA's Building Technology Committee in early July that all companies were originally aiming to have new water heater lines on the market by October 2M I that could meet the new vapor-resistant water heater standard. At this point, most companies are still testing the new designs, so he believes those products won't be widely available until next year. Expect the designs to include a new type of gas value, a special flame-arrestor plate below the tank, plus a few other features.

What will the new products cost? The initial price increase is $85 today, but Mahoney expects that cost to drop once the new designs become standard.

Higher water heater standards

Last year, the U.S. Dept. of Energy proposed increasing the minimum efficiency of water heaters. Gas-fired units would improve from an Energy Factor of 0.54 (54 percent efficient) to EF-0.59, and electric units would need to increase from EF-0.86 to EF-0.90. After much back and forth debate, the proposal was approved by the Clinton administration and upheld by the Bush administration. The new minimum efficiency requirement takes effect in January 2004.

Gas-fired water heater efficiency is measured by the combination of combustion efficiency (normally about 76 percent) plus stand-by losses from the tank into the room when the water heater is in stand-by mode. A number of water heaters currently manufactured already meet this higher efficiency standard. Changes usually involve use of heat traps (preventing hot water from being lost from pipes above the tank), a more efficient flue baffle (to improve heat transfer during combustion), plus an extra inch of foam around the tank.

Two years ago, an E-Star energy rater who shopped around found an EF-0.60 gas water heater on the market for just $25 extra to his builder customers. Most builders report the price difference is more like an extra $50 to $100. Once these water heaters become standard, the $25 price increase is probably about what you should expect. (Question: Longmont and Denver building codes have required this efficiency standard for several years; are they both being enforced?)

Backdrafting and spillage

The draft of warm air rising up a water heater flue is measured in very small units of air pressure, called pascals. You can typically count on between 5 and 10 pascals of positive draft pressure drawing in surrounding air. When the area in which the water heater is located is put under a negative pressure equivalent to the positive pressure in the flue, the combustion byproducts rising up that flue may backdraft-spilling back into the room and potentially causing health and safety problems.

As previously reported in this magazine, one-third of the homes in the 1999 Fort Collins housing study have negative pressures sufficient to be considered a potential safety hazard. (in the intervening two years, nothing has changed, based on parallel testing by E-Star around the state.) This is an unacceptable risk, both to buyers and builders.

What are your options? You can either reduce or eliminate the negative pressure problem, or you can purchase a water heater that won't spill byproducts of combustion back into the home.

There are excellent reasons for eliminating the negative pressure situation. Since the problem is caused primarily by leaking ductwork, reducing or eliminating those leaks addresses several problems simultaneously. By sealing ductwork, the house is made safer, the sizing of HVAC equipment (especially AC) can be reduced, equipment durability should improve, and comfort will increase. Not bad.

But can you count on this? Just because you specify tight ductwork doesn't mean it will happen. Several builders and HVAC contractors are experimenting with new ductwork designs that eliminate using building cavities for return-air ducts (more on this in a future article); this shows great promise, but will take some months to work out.

Then again, homeowners can create changes in their homes that cause negative pressure to return. Consider a colleague's test of a client's home this morning. Due to comfort problems (can't get cooled air to the bedrooms over a garage), they had a poorly informed HVAC contractor install an attic fan. When the attic fan runs, it pulls air from three holes in the ceiling connected to the house. This fan can create major negative pressure in the house. So can some down-draft kitchen exhaust fans.

Given the slow pace of change with ductwork, plus this type of homeowner factor, your best short-term option is to purchase a more fool-proof water heater product. Buy one that isn't atmospherically vented-one that doesn't passively draw house air up the flue past an open, dish-shaped draft hood.

Your four primary choices? First, buy a water heater with an induced-draft fan -- the type installed on 80 percent-efficient furnaces. Second, buy a PVC-vented appliance, one that brings in outside air to the appliance and another that carries away the flue gases. Third, buy a direct-vent appliance; it has to be placed right next to the exterior wall and vent through double-walled pipe out the rim joist. Fourth, buy an indirect or side-arm water heater that is fired by a boiler.

I strongly recommend purchasing and installing different appliances. Do they cost more? Absolutely. Count on at least a couple hundred dollars. But when I consult with individual clients, I virtually insist that such a water heater be part of the package. It's cheap insurance. Once this is pointed out to them, I get 100 percent agreement.

Footnote for the future: these safer water heaters normally don't achieve the type of higher efficiency (EF-0.59 and higher) that will be required in the future. So the industry has some work on its hands.

Steve Andrews consults with builders for E-Star Colorado and writes on energy issues (sbandrews@att.net). E-Star (www.e-star.com), is a nonprofit home energy rating system that works with both new and existing homes statewide.

2008 Built Green Colorado

Home Builders Association of Metro Denver, 9033 E. Easter Place, Suite 200, Centennial, CO 80112
(303) 778-1400 fax: (303) 733-9440  info@builtgreen.org

Last Updated: 10/05/2007