I have a Pentair Minimax Plus 400 gas heater. It is about 60 degrees here. Grand kids are visiting so I turned on the heater to heat my pool/spa. It has been running for 6+ hours with plenty of hot air near the heater but not even warming the outgoing water pipe. There is a cast iron manifold where the water inlet and outlet are connected but that manifold is also cold. All lights are normal, thermostat setting are at high and switch is set to Pool. The burners are running. It this normal behavior? Is there a troubleshooting guide available for this unit? Any and all help will be appreciated.