G1540TC = thermal cover helps maintain temperature, this is non electrical
G1540HTR = made to order G1540 unit that does control the temperature of the water coming out of the units. It is built with thermostat controlled heating pads.
WARNING: California Residents
This product and/or packaging can expose you to chemicals including Styrene, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.