I wouldn't compromise on the timer either. It is a 110.3(B). I guarantee when you look at the "fireman's switch" section of the installation manual they will tell you the pump needs to be wired to a timer that makes the pump run "X" minutes after the heater shuts off (X = 15 in the case of my StaRite 330kbtu). The safeties in the heater will shut the heater down but you still have a lot of residual heat in there and you will make steam. Playing with my IR thermometer I figured out 30 seconds to a minute will probably do the trick but the instructions are what they say.
