If the heater was just installed it may have been installed incorrectly. If this is not the case there may be an issue with the flow sensor, which will require a certified HVAC technician. Alternately, the filter may need to be cleaned.
To clean the filter, the unit must first be drained:
- Close the manual gas shut off valve.
- Turn off power to the unit, and then turn on again.
- Wait 30 seconds, and then turn off power to the unit again.
- Close the cold water inlet shutoff valve.
- Open all hot water taps in the house to remove the initial pressure.
- When the residual water flow has ceased, close all hot water taps.
- Unscrew the drain plugs (hot water outlet drain plug and cold water inlet filter) to drain the remaining water out of the unit. Have a bucket or pan to catch the water from the unit’s drain plugs.
- Wait a few minutes to ensure all water has completely drained from unit.
- Check the water filter located within the cold inlet.
- With a tiny brush, clean the water filter of any debris which may have accumulated and reinsert the filter back into the cold water inlet.
- Securely screw the filter