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Part number 550-142-054/1211
GV90+ gas-fired water boiler — Boiler Manual
20
Figure 23 Auto system supply temp regulation —
zone valve zoning
Figure 24 Auto system supply temp regulation —
circulator zoning
Multi-zone radiant heating system
Multi-zone systems require automatic regulation of the system sup-
ply temperature because of widely varying load conditions. Figure 23
(zone-valve zoning) and Figure 24 (circulator zoning) show suggested
piping for these systems.
Provide an automatic temperature control valve or
motor-operated valve which can be adjusted for the
desired supply water temperature. This is required to
protect the radiant system from excessive temperature.
Zone-valve zoning — The suggested piping uses a separate circulator
for system circulation to provide the higher flow typical of radiant
heating systems and to assure good temperature distribution in the
system when the return water temperature is low.
Circulator zoning — The GV90+ internal circulators must not be
removed. Provide a separate circulator for each zone.
Balancing, when required
—
Substitute a memory-stop
valve for one of the isolation valves in each zone to use
the memory-stop valve for balancing flow as well as
isolation.
Zoning with zone valves —
Provide a separate 24-volt
transformer to power the zone valves. Size the trans-
former to handle the total rated load of all connected zone
valves. Alternatively, use a zone valve zone controller.
Zoning with circulators — The GV90+ internal system
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. The sys-
tem circulator must be supplied by the installer.
Outdoor reset
Apply Figure 23 or Figure 24 for any system intended for outdoor reset
of the supply water temperature. Use a motor-operated three-way valve
and an outdoor reset temperature control system.
MINIMUM
Boiler loop pipe size
GV90+3/4
GV90+5/6
1”
1¼”
MINIMUM
Boiler loop pipe size
GV90+3/4
GV90+5/6
1”
1¼”
Legend
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 Supply temperature automatic mixing valve
11 Differential pressure by-pass valve
16 Cold water fill line — see Figure 15, page 14 for typical components
Install water piping (continued)
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