another heater installation question
 

I see in the manual one of the places the hook up the supply hose is off of the thermostat housing. When I pulled the plug I noticed its only 3/8. is that going to be a problem going from 3/8 the 5/8 hose? Will there be too much of a restriction? I would like to use this location as it seems like it would be very convenient but if not is there a better location for the supply hose?