Correct me if I'm wrong because I don't have a Heater to look at. If there is a spring in there and I don't see any use for it as far as heater operation, it means that it is loading the shaft against a cotter or pin to retain the shaft inside the can or at least involved in shaft retention somehow. Unless it's a torsion spring, in which case it's for return. Maybe just tension on shaft to keep flapper in open/close position? If I could fiddle with it I could figure it out.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
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