Thanks for the information so far L1ftmech and Partsguy5. We used the fan as the front reference per the application guide. We originally tried the 3100019 for the H20-II but after talking with zero start tech support they suggested using the 3100016 which is for the H20 and to them it appeared to be a little smaller. Both heaters are the same diameter, wattage, and voltage. They only had a drawing for one of them so they couldn't confirm it.
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