Williamson-Thermoflo GWC-070 Manual page 21

GWC -
gas fired water boiler
Install water piping
Piping snow melt systems or combination
snow melt/space heating systems
Combination snow melt/space heating systems can have return water
temperature below 60°F, and the return temperature will fluctuate. So
these systems require automatic return water temperature as shown in
Figure 25 (zone-valve zoning) or Figure 26 (circulator zoning).
Select an automatic temperature control valve or motor-operated valve
which can be adjusted to provide a return water temperature of at least
60°F. Any setting higher than 60°F will also be acceptable.
Zone-valve zoning — The suggested piping uses a separate circulator
for system circulation to assure good temperature distribution in the
system when the return water temperature is low.
Circulator zoning — The GWC internal circulators must not be re-
moved. Provide a separate circulator for each zone.
The return water temperature to the boiler must be
at least 60°F. Provide and apply means to regulate the
return temperature. Failure to do so can result in boiler
control operation problems, causing possible significant
property damage.
Zoning with zone valves
diagrams in this section is shown with an isolation valve
on each side. Substitute a memory-stop valve for one of
these in each zone in order to use the memory-stop valve
for balancing flow as well as isolation.
Provide a separate 24-volt transformer to power the zone
valves. Size the transformer to handle the total rated load
of all connected zone valves.
Zoning with circulators
circulator cannot be removed from the boiler for use as
one of the zone circulators. It must remain as shipped
from the factory to allow proper flow control inside the
boiler. You will need a circulator for each zone. Provide
circulator relays or circulator zone controller.
tem circulator must be supplied by the installer.
1 Isolation valves
2 Automatic air vent (with diaphragm-type expansion tank), or
connect to tank fitting (closed-type expansion tank).
3 Diaphragm- or bladder-type expansion tank, if used (For closed-
type expansion tank, pipe from top of air separator to tank fitting
as in Figure 15, page 14.)
4 Zone valve
5 System or zone circulator
6 Flow/check valve
7 Hose bibb purge valve
8 Boiler pressure/temperature gauge
9 System supply temperature gauge
10 Return temperature automatic mixing valve
11 Differential pressure by-pass valve
16 Cold water fill line — see Figure 15, page 14 for typical components
Part number 550-142-056/0411
— Boiler Manual
(continued)
— Each zone in the piping
— The GWC internal system
Legend
Auto return temp regulation — circulator
Figure 25
zoning
Auto return temp regulation — zone valve
Figure 26
zoning
The sys-
MINIMUM
Boiler loop pipe size
GWC-070/105 1"
GWC-140/175 1¼"
MINIMUM
Boiler loop pipe size
GWC-070/105 1"
GWC-140/175 1¼"
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