Make sure the unit is installed properly using the Proper Installation section (p. 6) of this guide.

Check the flow and temperature right at the unit at the pressure relief valve. If the flow rate and temperature are correct at the PRV, then the problem resides elsewhere in the plumbing line. The following could be plumbing line problems:
o Check for cross plumbing between cold water lines and hot water lines. See the Procedures section (p. 21) for instructions.
o Check to see that a check valve is installed between the pump discharge and the connection to the cold water supply. Inspect the check valve for proper operation. If there isn’t one installed, or if it is malfunctioning, cold water may be back?feeding into the system.
o Problems with a recirculation system:
? Check that a check valve is installed between the pump discharge and the connection to the cold water supply.
? Check to see if the pump is operating properly.
? Check for air cavitation. The pump will be very hot or chattering.
? Check the directional indicator on the pump flange.
? Check the sizing of the pump – a minimum flow of 2 gpm is required.

Check gas supply
o Verify the gas supply lines are sized for the maximum Btu/h demand, as indicated in the Proper Installation section (p. 6) of this guide (See the specification page p.3 at the beginning of this manual for gas input rating).
o For LP models, there may not be enough gas left in the propane tank.
o Verify that the supply gas pressure is within specification, not only when the heater is in standby, but while the heater is running on maximum fire as well. This may be caused by a malfunctioning gas supply regulator.

o Verify that the exhaust venting is installed to manufacturer’s specification.
o Verify that the vent run does not exceed the maximum limit (50 ft.)

The filter on cold water inlet should be clean; look for signs of hard water scaling.

Check to make sure that the clear tube between the proportional gas valve and the bottom of the combustion chamber is connected.

On well systems or even on some city water systems, water pressure fluctuations (especially on low flow) of 8 to 10 psi will result in flow rate fluctuations, which will in turn result in minor temperature fluctuations.

Flow sensor or water control valve may be compromised. Contact the Technical Department.