Fantech HEPA DM 3000P, Installation, Operation And Maintenance Manual

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Troubleshooting
A) Problem: When the DM3000P is on "STANDBY" it does not come ON.
1) The pressure switch's positive pressure port is not connected.
Solution: Use the supplied tube and grommet and install one end of the tube to the supply (positive pressure) air duct and
the other end of the tube to the pressure switch connection on electrical panel next to the power cord.
2) The pressure differential between the return (negative) air and the supply (positive) air of the forced air system is less than 18 Pa
(0.07 in wg).
Solution: Check the static pressure difference by connecting the LOW pressure side of a manometer to the return air duct
and the HIGH pressure side of the manometer to the supply air duct. If it reads less then 18 Pa (0.07 in wg), the pressure
switch will not work. The only remedy is to set the rocker switch to "CONTINUOUS". Check this differential pressure on all
available speeds of the forced air system.
B) Problem: When the DM3000P is on "STANDBY" it does not turn OFF.
1) Other exhaust equipment in the house may interfere with the operation of the DM3000P by creating pressure differences in the
forced air system's duct work.
Solution: If this is a constant problem, disconnect the positive pressure tube from the DM3000P to the supply air duct.
Check if the DM3000P turns ON when the forced air system is on and turns OFF when the forced air system is OFF.
Depending on the furnace and the duct design, the negative static pressure in the duct may not be more than 17Pa (0.07"WC). As such, the pressure
switch will not activate the DM3000P while it is on "STANDBY" mode.