Full and gas water heater inlet valve filter position
The filter of water heater is installed: water and cold water connection. The filter of water heater is to prevent impurities into water heater in tap water, cause heat exchanger in the water heater to make a scale, block and so on. So, the strainer is usually installed on the pipe joint before the tap water enters the water heater.
The filter should be cleaned regularly to prevent the impurities from silting the filter, causing the intake to be too small and the water heater can't be started.
On the right side of the water heater, where the inlet pipe is connected, there is a water flow size adjustment knob, which is taken apart and should be in there.