This sounds to me like a check valve before the water heater may help if the issue is reverse flow when the petal is first pushed. Pushing the pedal causes a reduction in system pressure. The pressurized air in the hot water system causes water to be pushed backward through the heater. When the pedal is released, pressure increases and water pushes back through the heater, triggering the flow switch, which starts the combustion air fan, but not long enough to complete the pre combustion purge cycle before the flow stops due to the air being compressed back up to system pressure. The fan then runs through it's post combustion cycle and shuts down.
Installing a check valve before the heater would prevent the backward flow through the heater. That keeps the hot water system fully pressurized and stops the hot water system from needing to be re-pressurized after each flush even if air is trapped in it.
Sent from my iPhone using Forest River Forums
Lou and Paula
2014 Rockwood 8289WS UltraLite w/Revolution Pinbox Engaged.
2011 F250 Power Stroke Super Duty King Ranch Super Crew Cab w/Reese 16K Hitch
Lou & Paula
2014 Rockwood 8289WS Ultra Lite w/Reese Revloution Pinbox.
2011 F250 Power Stroke Super Duty King Ranch Super Crew w/Reese 16k Fixed Hitch