Weil-McLain 2 Series Manual page 21

®
SlimFit Series 2
Install water piping
WATER CHILLER systems — ZONE
VALVES primary/secondary
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
on all boiler loop piping (connecting boiler to and from the primary/
secondary connection, item 21).
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 an-
tifreeze 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 Priori-
ties 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
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 550-100-180/0917
COMMERCIAL CONDENSING GAS
(continued)
See Figure 20.
pipe size shown in Figure 12, page 15
Legend — Figure 20
- — Boiler Manual
FIRED WATER BOILER
Chilled water system plus optional DHW
piping — primary/secondary piping
DHW applications, assign DHW Input(s) to determined 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