Class I - Dangerous
When an RM or ZM model heatbox (replacing a ZA or RA model heatbox) is inserted into a ZAC wall can and wired through a fitting in the top-left wall can knock-out (see the picture), the RM or ZM model has the potential for continuous heater operation, regardless of thermostat settings or room temperature. This can cause the heater to overheat and catch nearby combustibles on fire.