cycles of 15 seconds). The RT850 is compatible with both mechanical and 2-wire or 3-wire electronic thermostats (with or without batteries). I The RT850 must be mounted on a 4” x 4” electrical box. WARNING: The relay must be mounted so the heat sink fins are vertical or facing upwards. You should also provide space above the heat sink for warm air to escape. Disregarding this warning may result in improper operation of the relay. Refer to the diagram below for correct mounting guidelines. .. All