Weil-McLain SlimFit 2 Series Manual page 21

SlimFit ® Series 2
Install water piping
WATER CHILLER systems — ZONE
VALVES primary/secondary
Figure 20
1. The chiller must be piped in parallel with the boiler.
2. Use appropriate valves to prevent chilled medium from entering
boiler.
3. Circulator zoning option — The space heating system can be zoned
with circulators if a separate circulator is supplied for the chilled water
loop. Install a separate circulator for each zone.
4. The flow/check valve shown on the boiler outlet piping prevents
gravity circulation in the boiler loop during DHW heating.
Use at least the MINIMUM pipe size shown in Figure 12,
page 15 on all boiler loop piping (connecting boiler to and
from the primary/secondary connection, item 21). Primary/
secondary piping shown ensures the boiler loop will have
sufficient flow. For other piping methods, see guidelines on
page 15.
If antifreeze is used in the system, consider the effects of
antifreeze on circulator sizing and DHW performance. Some
local codes may require double-wall DHW heat exchanger
design. Use only the antifreeze listed by Weil-McLain for use
with this boiler. See page 105 for details.
Chilled medium, if used, is piped in parallel with heating boiler
as shown in Figure 20. Use appropriate valves to prevent
chilled medium from entering boiler. If boiler is connected
to heating coils located in air handling units where they can
be exposed to refrigerated air, use flow control valves or
other automatic means to prevent gravity circulation during
cooling cycle.
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 direct connection—Pipe from the near-boiler piping to the
DHW tank's boiler connections as shown.
2. DHW as zone— Not recommended for this application.
3. Priority of DHW/Space Heating:
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 simultaneously.
Controlling the circulators
1. The control can control up to four circulators (boiler circulator
and three others). Refer to Field wiring, beginning on page 47, for
instructions on wiring to circulators.
2. The factory default settings are: all three inputs are setup for Space
Heating (Priority 2). Each input correlates to its respective circulator
output. For DHW applications, assign DHW Input(s) to determined
1 SlimFit 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)
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
15 Closed-type expansion tank
16 Water chiller
Part number 550-100-561/0224
commercial condensing gas
(continued)
See
Legend — Figure 20
- — Boiler Manual
fired water boiler
Figure 20
Chilled water system plus optional DHW piping
— primary/secondary piping
Priority (1, 2, or 3). Priority 1 is defaulted to DHW for DHW
Priority applications.
3. For more than 3-zones, use Weil-McLain WMZV zone valve
controller.
Connect zone valve end switches to a Space Heating
Priority input, (default Priority 2) to use default settings
Connect system circulator to corresponding output.
Use isolation relays if connecting 3-wire zone valve
end switches to the inputs.
17 Check valve
18 Strainer
19 Balancing valve
20 Make-up water supply
21 Primary/secondary connection (tees no more than 8 pipe diameters
apart)
24 Strap system supply and return sensors to lines as shown, 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.
31 Install a union on the boiler supply and return connections as close
as possible to the boiler to allow disconnection for service when
required.
Items supplied with boiler
Items supplied by others
21