Xylem MM 200G Series 64 Low water Cut-Offs - Manual (Page 4)

4
HOT WATER
BOILER
DO NOT REDUCE
THIS 2 1/2" DIMENSION
BLOWDOWN
VALVE
MODEL 764
LOW WATER
CUT OFF
a. See figure 1. The 2 1/2" (65mm) tapping on
the boiler has to be above the minimum safe
operating level, as determined by the boiler
manufacturer. On steam boilers, make sure
the line on the casting is above the lower
gauge glass nut.
NOTE: Do not reduce the
2 1/2" (65mm) tapping, as this would compro-
mise low water protection.
Model 764 – For Steam or Hot Water Boilers
INSTALLATION –
TOOLS NEEDED:
One (1) flathead screwdriver and two (2) pipe wrenches.
STEP 1 - For Steam or Hot Water Boilers where 2 1/2” (65mm) Tapping is Provided
HOT WATER
BOILER
DO NOT REDUCE
THIS 2 1/2" DIMENSION
MODEL 764
LOW WATER
CUT OFF
BLOWDOWN
VALVE
SUPPLY
LINE
a. See figure 2. If there are no 2 1/2" (65mm)
tappings on a hot water boiler, the 764
control can be mounted on a 2 1/2" (65mm)
tee on the riser going to the radiation or
compression tank.
NOTE: Do not reduce the
2 1/2" (65mm) tapping, as this would compro-
mise low water protection.
STEP 2 - For Hot Water Boilers where 2 1/2” (65mm) Tapping is not Provided
Test the Model 764 Before Leaving the Site
While the burner is operating open the blow-down valve, causing the water level to drop in the float chamber.
As the float drops the alarm circuit (if used) closes first; then on further drop the cut-off circuit will open,
shutting the burner off. NOTE: If no Test-N-Checks (TC-4) valves were used, do this test before filling the
system completely.
IMPORTANT: Instruct boiler attendant to blow down the float chamber at least once a week during the heat-
ing season, if operating pressure is below 15 psi (1 kg/cm 2 ). If above 15 psi blow down once a day.
NOTE: On a new boiler installation, leaky system, or where the quality of the water is poor, blow down the
control more frequently.
Protect yourself when blowing down controls, hot water will flow out of the drain pipe attached to the blow-down valve.
Failure to follow this caution may result in serious burns.
CAUTION
Figure 1
Figure 2