I have an AquaStar propane tankless hot water heater. I ran out of propane this morning. This afternoon I lit the pilot light. When I run the water I can see the flames heating but the water is not heating immediately. It was working fine until I ran out of propane. Should I have done something other than just light the pilot?

Many tankless hot water heaters automatically adjust water temperature to its minimum setting when turned off. See if you can re-adjust the temperature back to 125 F.. Also, I would read Trouble shooting in heater's manual... Milo