The tank-less WH have to detect hot water flowing. They do that by sensing a pressure drop from their inlet to outlet.
If the city water pressure is too high or the flow too plentiful, the WH won't detect usage and therefore not cycle.
My opinion is that they are an overrated solution to a problem that doesn't exist. Tank-type water heaters have been doing a great job in RV's for 50 years. The modern pilotless ignition saves plenty of fuel.
You've got a couple of choices:
- Buy a pressure regulator to limit the pressure and flow from the city water
- Keep your fresh water tank topped up and only use the RV's water pump
- Downgrade to a tank-type water heater
Others will chime in with suggestions...
TT 2015 19RD "TheJayco"
TV 2003 F-350 "Montblanc" - Housebroken chore truck
Sitting in The Cheap Seats.
And proud of it!