Solar, Solid-Fuel, and Specialty Heating Systems
This domain tests solar thermal, solid-fuel, and specialty heating installations: collector mounting, freeze protection, relief and expansion, chimney and flue requirements, floor protection, clearances, and specialty equipment limitations.
Core rules
- Solar thermal collectors must be structurally supported and mounted per listing. The loop needs expansion control, relief protection, isolation valves, and freeze protection appropriate to the climate and fluid.
- Solar storage tanks and heat exchangers must be protected from overpressure and overheating. Relief discharge must terminate safely. Potable-water connections require backflow protection.
- Solid-fuel appliances must be listed, installed on approved floor protection, and connected to a listed chimney or vent. Clearances to combustibles are critical and cannot be reduced by field-built shields unless approved.
- Solid-fuel appliances may be prohibited in certain locations, such as garages, where gasoline vapors can be drawn in. Check occupancy and location restrictions.
- Specialty systems such as pellet stoves and direct-vent appliances require listed venting and manufacturer clearances. Chimney height and termination affect draft and safety.
Worked example
A solar hot-water loop is installed with an expansion tank but no pressure relief valve because the tank is rated for high pressure. The reviewer should still require relief protection for the loop and storage vessel as designed, with safe discharge. An expansion tank controls pressure changes but does not replace overpressure protection.
Traps
Omitting relief protection on solar loops; ignoring freeze protection; installing a solid-fuel appliance in a prohibited location; reducing listed clearances with unapproved shields; and using an unlisted chimney.