How Heated Waterer Thermostats Work (35°F On Explained)
It maintains just-above-freezing, not warm
Bimetal thermostat closes ~35-40°F (turns heat on), opens ~50-60°F (off). Water 38-45°F feels cold to you, perfect for birds – warm water grows slime + wastes power.
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Test: plug meter shows 0W above 50°F ambient even plugged in – normal. If 0W at 20°F, thermostat/element failed. See tripping, cost.
Controls source
Bimetal stats close ~35-40°F, open ~50-60°F – verify draw with plug meter. Rates context: EIA, DOE.