Pending water heater regulatory changes will impact the manufacture and installation of water heaters from three directions: ozone depletion concerns mean changing the blowing agent used in the insulation, safety concerns force the introduction of designs that resist the ignition of flammable vapors; and the installation of high-efficiency gas-fired water heaters affects venting requirements. Most residential water heaters are insulated with polyurethane foam. Currently, water heater manufacturers use HCFC-141b, an ozone-depleting substance, as the blowing agent. As a result of the Montreal Protocol, after 2003 manufacturers must use blowing agents with Zero Ozone Depletion Potential. This paper compares the efficiency and cost effectiveness of using two leading blowing agent replacement candidates, HFC-245fa and water-blown foam. Current designs for gas-fired water heaters rely on a standing pilot to ignite the main burner. If flammable vapors are in the air around a water heater unintended ignition is possible. This is a potential safety problem addressed by an ANSI Standard change which will become effective in 2001. Water heater designs with increased efficiency may cause condensation problems in the venting system. To prevent this, certain venting systems may require Type-B vent connectors or relining of masonry chimneys. This paper discusses the expected solutions to these changes and possible impacts on water heater costs.
展开▼
