Figure 16
Variable Primary Flow, DHW as Zone
SVF
™
Series 1
Commercial Condensing Gas-Fired Water Boiler
— Boiler Manual
Part number 550-100-250/0819
19
ZONE VALVE zoning - Variable Primary
Flow
See Figure 16.
This configuration is for applications that use a variable flow system
pump.
1. Install a system circulator (supplied by installer) capable of delivering
the necessary variable flow and head as shown.
2. A bypass with a differential pressure valve or pressure reducing
valve may optionally be used between the near boiler supply and
return piping in high flow systems. If used, ensure the System Supply
Temperature sensor is placed AFTER the bypass.
3. A flow switch is recommended if system flow could drop below
the minimum flow specified on page 15 in Figure 10. A 1"FNPT
connection is located on the boiler return pipe.
Expansion Tank required
1. Provide a system expansion tank following the guidelines on page 16.
2.
DO NOT
use a closed-type tank if connecting to a water heater that
is equipped with an automatic vent.
Domestic Hot Water (DHW) tank, if used
1. DHW as a zone – A DHW tank can be connected as a zone if a
DHW tank is NOT already connected to the boiler. See Advanced
Manual to configure Boiler Pump to run during DHW demands
and change TARGET MOD SENSOR to System Supply.
2. System Priority choices:
a. DHW Priority – DHW is priority over space heating. Use
Priority 1 for DHW; Priorities 2 and/or 3 for space heating.
The control will not run multiple priorities simultaneously.
b. Space Heating Priority – Space heating is priority over DHW.
Use Priorities 1 and/or 2 for space heating; Priority 3 for
DHW. The control will not run multiple priorities simultane-
ously.
c. No Priorities – Space heating and DHW can occur simultane-
ously at same Supply Max temperature. Use only if DHW is a
zone in system. Assign DHW and Space heating to the same
Priority. Do not use outdoor reset for this application.
Controlling the circulators
1. The control can control up to four circulators (boiler circulator and
three others). Refer to Field wiring, beginning on page 59, for instruc-
tions on wiring to circulators.
2. The factory default settings are: all three inputs are set up for Space
Heating (Priority 2). Each input correlates to its respective circulator
output. For DHW applications, assign DHW inputs to determined
Priority (1, 2, or 3). Priority 1 is defaulted to DHW for DHW Prior-
ity applications.
3. For more than 3 zones, use Weil-McLain WMZV zone valve controller.
Legend — Figure 16
1
SVF
TM
boiler
2
Indirect water heater (DHW), if used
3
Boiler relief valve (see page 14 for piping details)
4
Relief valve discharge piping (see page 14 for details)
5 DHW
circulator
6 Isolation
valves
7
System circulator (see information above for wiring)
8
Diaphragm (or bladder) type expansion tank (see page 16 for piping of closed-
type expansion tank, if used)
9
Air separator [with automatic air vent only on systems using diaphragm
(or bladder) type expansion tank]
10 Flow/check
valves
11 Purge/drain
valves
12 Boiler
circulator
13 Zone valves, typical
20 Make-up water supply
21 Primary/secondary connection (tees no more than 8 pipe diameters apart).
23 DHW secondary connector piping — no more than 8 pipe diameters apart.
24 System supply and return immersion sensors, at least 6 pipe diameters
(but no more than 3 feet) from boiler connection tees.
25 Systems using high-head pumps may require a bypass pressure regulator to prevent
damage to control valves.
26 External drain/blowdown valve, when used.
32 Flow switch, by others
33 Strainer,
recommended.
34 High flow systems may require a bypass pressure regulator/pressure reducing
valve to prevent excessive flow in heat exchanger.
Install water piping
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