Water Heaters and Radiant HeatingThe July 16 letter, “Water Heating Prohibition” by chief boiler inspector Darryl Peetz of the Missouri Department of Public Safety, is misleading and a cause of concern for installers of combination space heating and domestic hot water systems. His comments leave readers with the impression that combination systems are illegal and dangerous and that health regulations prohibit their use. This is not the case.
Issues regarding combination systems have been thoroughly addressed by all code jurisdictions, and it has been conclusively determined that the systems do not add any concerns for the health, safety, or welfare of the user.
The combination systems do not come under boiler regulations according to GAMA, CGA, the National Boiler Board, or ASME, and the systems meet the requirements of BOCA, SBCCI, and IAPMO. ANSI has adopted a National Standard for combination systems (ANSI-Z21.10.1 and Z21-.10.3).
Combination systems using gas water heaters were developed starting in 1979 as an alternative to the use of heat pumps and strip heat in apartments, condos, and homes. The acceptance by water heater manufacturers encouraged refinement and greatly increased the usage of combination systems. Today, there are hundreds of thousands in use from Florida to Alaska. The properly installed combination systems have proved to be energy efficient, reliable, very cost effective, and easy to service.
Gas water heaters are designed to ANSI standards and certified by CSA (formerly AGA) and do not have a UL listing. Combination systems with electrical components are designed to ANSI standards and are listed by ARL, UL, ETL, or other national listing agencies. These listings are not voided when the equipment is used for space heating applications.
Mr. Peetz has encountered radiant heating systems in car washes and other small commercial applications that used a water heater to provide the source of heat only for space heating. This is not a combination system, and is contrary to Missouri codes. I believe that he has no objection to combination systems that are properly installed in accordance with ANSI standards and all components and piping are suitable for use with potable water.
Jim Whiting Sr. Codes Consultant Alternative Technology Raleigh, NC