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Water heater thermostat control board

Jet

New Member
Joined
Jun 22, 2021
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118
Does anyone know how many amps a water heater circuit board and thermostat draws if there is no element connected. I plant to use a DC heating element connected to the battery using a relay. If the heating element isn't power through the AC power supply, how many amps would the other electronics probably use on a basic 20 gallon water heater without a digital display or anything like that. Would it be crazy to hook the AC to a light switch if the amperage is very low. That way the water heater can be turned on and off with the switch!
 
Basic water heaters just use the thermostat and element. So zero consumption when it’s not heating. Fancier ones with electronics and “options” gotta be less than 25W, probably less than 5. As long as your electronics are separated from the HVDC from the panels, maybe. Make sure it’s a DC rated relay - that might be the hardest part of your project. DC versus AC stuff and they are generally not interchangeable.

While you are at it, put a tempering valve on the water heater and change your temp set point to something higher, like 140-150. Temper it down to 120 and voila. Your 20 gal water heater is now a 30 gallon for no additional space.
 
Basic water heaters just use the thermostat and element. So zero consumption when it’s not heating. Fancier ones with electronics and “options” gotta be less than 25W, probably less than 5. As long as your electronics are separated from the HVDC from the panels, maybe. Make sure it’s a DC rated relay - that might be the hardest part of your project. DC versus AC stuff and they are generally not interchangeable.

While you are at it, put a tempering valve on the water heater and change your temp set point to something higher, like 140-150. Temper it down to 120 and voila. Your 20 gal water heater is now a 30 gallon for no additional space.
The space of the water heater wasn't really a problem, just how long it takes to heat up. I think I'll go with 20 gallon. A 10 gallon maybe too small as it won't be enough for the shower. Crydon makes lots of heavy duty Dcdc relays up to 160A. Thanks for your input. I just realized a normally close relay won't consume unless the water heater needs the heat! I'll research what a tempering valve is.
 
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