There isn't a push button on the AquaHot display for the middle zone. That is because there are no "radiators with blowers" separate for that area. However, I believe it is because the AquaHot radiators for the front zone all operate identically.... the radiator under the kitchen sink area, the one in my half bath that blows out into the living area (by the refrig in our B) and the radiator under the center console in front dash all blow simultaneously and in "unison". The rear radiators are under the vanity and in the wall between the rear bath and the bedroom.
The draft while traveling, I have no clue.... ours does not. Sounds like all three of those radiators may have the fan running and no hot water through the "radiator" or you have a hole somewhere behind the kitchen cabinets that is open to the outside air.
Gary and Dee, Zowie and Bowie (traveling cat sibs)
2019 Cornerstone 45B, X15-605hp, Imperial, Spartan K3,
2013 Honda CR-V toad, Demco Excali-Bar II,
Demco Baseplate, Demco Toad Light system, 73 de W5FI