Bell & Gossett DN0134D Domestic Pump Vacuum Heating Units Series VLR - Manual (Page 2)

2
DESCRIPTION AND INST ALLATION
The Series VLR vacuum heating units ar e designed to serve the
dual purpose of pumping accumulated condensate back to the
boiler feed tank and maintaining vacuum in the condensate
system. This vacuum will draw air out of the system on start-up
and facilitate the flow of steam thru the heating system.
One pump/vacuum producer/discharge valve assembly
controls both the condensate discharge and the production of
vacuum. Two pump (duplex) units have a second assembly for
backup and to provide extra capacity to handle peak loads.
Various electrical controls are offered to meet system require-
ments. These controls are normally supplied as part of the
assembled unit and a wiring diagram is furnished with the unit.
Refer to this electrical diagram as required.
The units respond to both changing condensate levels and
system vacuum requirements. The Series VLR units feature a
low inlet height and therefore have a second float (in lower
compartment). As condensate accumulates in the lower com-
partment, this float starts the pump and siphons the conden-
sate to the upper chamber.
In operation the centrifugal pump circulates condensate from
the upper compartment thru the multi-jet nozzle creating multi-
ple jets of water entering the venturi. These jets entrain air and
gasses creating a smooth steady vacuum in the lift manifold
and in the condensate system. The air and gasses are sepa-
rated in the upper compartment and vented to atmosphere.
See Figure 1.
Low system vacuum or high water in the upper compartment
or high water in the lower compartment will start the pump to
create vacuum and transfer water to the upper tank. High water
level in the upper compartment will also cause the discharge
valve to open.
When the vacuum and float switches have been satisfied and
the pump stops, the check valve in the lift manifold closes, pre-
venting the return of air and water to the system.
The solenoid operated discharge valve is opened in response
to the condensate level float switch in the upper compartment.
Controlled opening of the discharge valve holds sufficient back
pressure in the nozzle body that the vacuum producer con-
tinues to function even when discharging condensate (simul-
taneous ratings).
NOZZLE BODY
MULTI-JET NOZZLE
VENTURI
PUMP SUCTION
SOLENOID OPERATED
DISCHARGE VALVE
DISCHARGE
LIFT MANIFOLD
CHECK VALVE
CENTRIFUGAL PUMP
LOWER COMPARTMENT FLOAT SWITCH
UPPER COMPARTMENT FLOAT SWITCH
STRAINER
LOW INLET
VACUUM GAUGE
VACUUM BREAKER
VACUUM SWITCH
AIR VENT
OPERATION IS SIMPLE, EFFECTIVE AND RELIABLE
FIG. 1 CUT -AWAY VIEW OF SINGLE SERIES VLR SINGLE UNIT: TYPICAL OF ALL SINGLE AND DUPLEX MODELS
FIG. 2 SERIES VLR VACUUM PRODUCER
AIR VENT
RECEIVER INLET
MULTI-JET NOZZLES
VENTURI
NOZZLE
BODY
CENTRIFUGAL PUMP
DSK-1328
SOLENOID
DISCHARGE
VALVE