The E+ heater cannot be used in damp or wet environments as the IP rating of the E+ heater is 10B, 'not for use in damp or wet environments'. For full details please see the E+ installation manual (https://www.reznor.co.uk/wp-content/uploads/2024/08/Reznor-e-Installation-Manual-EN-2024-06-D301600-Iss-0-print-quality-1.pdf).
Can the E+ heater be used in damp or wet environments?
Information on Reznor's range of warm air heaters