Pilot Water Heater Replacement PartThermostat/E.C.O. 110 VACAtwood part number: 91873Atwood 91873 Pilot Water Heater Replacement Parts - Thermostat/E.C.O. 110 VAC. Atwood Mobile Products, LLC has been a world leader in designing, engineering and manufacturing appliances and hardware for the RV industry for over 30 years. Whether it's our constant drive for innovation and improvement or our unwavering commitment to our customers it's no coincidence that Atwood Mobile Products, LLC has found itself an integral part of the RV industry for now and many years to come.