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For installations subject to UL726, a second operating control that senses water temperature is also required (not provided). Use an L4080B or equivalent. Install in the supply piping near the boiler. 2. Steam Boiler Controls: a. Install the limit / operating control, pressure gauge, gauge glass trim and safety relief valve. See Figure 7.2 (Section 7), Figure 3.7 (float boilers) and cover photo (probe boilers). b. For installations subject to UL726, a second operating control that senses steam p