1. Central air conditioners
2. Central heating (see above) with air conditioning (1H/1C)
3. Hot water system (steam or gravity) with or without pump
4. Central heating - gas, oil, electric or high-efficiency furnace (1H)
5. 750 mV heating systems
6. Heat pumps without auxiliary heating (1H/1C)
7. Dimensions
(in.) 4 11/16 in. High X 2 7/8 in. Wide X 1 1/8 in. Deep