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It is recommended that a bleed valve be installed in the discharge line, or in a line from the vent port to the
reservoir. This will allow the pressure in the pump to be relieved for service.
Installing a bleed valve is especially necessary in hot water application to prevent injury.
Pipe, valves and fittings must have a pressure rating equal to or greater than the maximum system pressure.
A bypass or pressure relief valve should be installed in the discharge line if there is any possibility the pump may
operate against a closed valve in the discharge line.
Minimum flow is required for proper cooling and lubrication of the pump. Operating below the following mini-
mum pumping rates could cause damage and premature failure could occur.
Series
To avoid damage to the pump, make sure on the suction side of the pump that there are no airlocks in the
system. The suction pipe should be level or slightly rising.
Correct Installation
Suction Pipe Sloping Up
Make sure that the system is properly installed and primed as instructed in the installation section.
Check that the suction valve is fully open and the discharge valve is in the open position.
Caution: Prolonged operation of the NV Series pump with either valve in the closed position will cause
severe damage to the pump.
Check to make sure all electric connections are correct.
Apply power to the motor.
Check motor rotation. Shaft rotation must be counter-clockwise when viewed from back of motor. On 3 phase
motors, if the rotation is not correct reverse any two leads to the starter. The rotation will now be correct.
Check that the noise, vibration, pressure, voltage and amps are at normal levels.
Warning: Webtrol NV Series pumps are designed for continuos and normal on/off operation.
Rapid cycling can cause high heat and loading that can cause damage to the pump or motor.
Minimum Pumping Rate
Flow Rate
NV6
2 GPM
NV12
4 GPM
NV25
7.5 GPM
NV45
10 GPM
NV65
10 GPM
Suction Pipe Belled Down
Series
NV85
NV120
NV180
NV280
NV400
Suction Pipe Sloping Down
Operation
- 7 -
Flow Rate
20 GPM
30 GPM
30 GPM
50 GPM
100 GPM
Incorrect Installation
Air Pockets
Suction Pipe Belled Down
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