If the Rain cap is blocked, or not long enough, the portable tankless water heater will shut off after a few minutes.

The portable tankless water heater requires a minimum of about 0.75 gallons per minute (2 liters) and a minimum of about 20 PSI / 1.38 bars. Note: water pressure is at the lower end of operating parameters. You will need a sustained water pressure of approximately 40-60 PSI / 2.7-4.1 bar for adequate use if you are using a 12/18/120/240-volt pump. See ADJUSTMENT in previous section above.

Out of, or low on gas. Propane gas cylinders sometimes are contaminated with air, especially new tanks upon their first filling. Cycle the portable tankless water heater on and off by using the shower head switch several times (5) to purge the air from the gas. If this doesn’t clear the air then the tank must be purged.

One of the ignition sensors is bent and/or too close to the burner. Look to ensure that the ignition pins and the heat sensor are completely vertical and they do a 90 degree to the back of the box. If they are not straight (i.e. a 45-degree angle) then you can straighten them with pliers.

The thermocouple is either too high or too low to complete the circuit. Check to ensure that the thermocouple is flush with the hole in the heat exchanger.

The gas sensor wire (looks like a black ground wire on the gas regulator) flange might have come loose or is no longer connected.

There is a faulty heat sensor. This is usually diagnosed by taking the front case off the portable tankless water heater and let it run. If it continues to operate, then one of the sensors and/or the wire harness needs to be replaced. This may also be caused by insufficient clearance on the back of the portable tankless water heater where most of air intake is.

The valve on the propane tank should be all the way “Open”.

Fresh batteries are required for ignition spark. Make sure batteries are aligned in the proper polarity (+/-).