Water Flow Sensor - Girard Products GSWH-2 Technical Manual

Hot water flow on - Pre-Trial for Ignition

Water Flow Sensor:

As the water flow increases the board will increase the BTU's to compensate for the lower temperature rise. As the
water flow decreases the board will decrease the BTU's to compensate for the higher temperature rise.
The water flow sensor or water flow meter gives the actual water flow measurement to the control board. As water flows
through the flow meter. The fins in the flow meter spin the water through the flow meter which turn the magnetic impeller.
The board sends 5vdc to the flow meter. The Reed switch on the side of the flow meter turns on and off quickly as the
magnetic impeller turns past it. This changes the "frequency" of the power coming back to the board. The board actually
reads the "frequency" determining how fast the impellers are turning. The flow meter cannot be tested with a resistance
check.
The simplest way to determine that the board has confirmed that the water flow meter has engaged is by examining
UCP. If the water flow icon (a shower head symbol) is active on the User Control Panel when the hot water faucet is
turned on then the flow meter can be eliminated.
The control board starts the operation of the water heater when the water flow exceeds .80 GPM (+/- 10%).
Confirm the actual water flow by timing how long it takes to fill a gallon container. Divide 60 seconds by the seconds
measured to come up with the GPM.
If the water flow is too low then you will need to inspect the
Valve adjustment on the water heater. Ensure that it is opened all of the way
up.
Other causes of reduced water flow are plumbing restrictions, pressure
regulators, water filters and insufficient shore or pump water pressure.
Water Control
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