Weil-McLain 2 Series Manual page 18

®
SlimFit Series 2
Install water piping
Zoning with zone valves — alternate
High-flow-rate/high-head-loss DHW
circuits
See Figure 17.
This configuration is for applications requiring DHW circuit flow rates
higher than allowable for the boiler, or for high pressure-drop coil-type
DHW tanks, connect the piping as in Figure 17. The DHW water only
flows through the secondary circuit connection piping. The primary/
secondary piping shown ensures the boiler loop will have sufficient flow.
It also avoids applying the high head of the boiler circulator to the zone
valves.
1. Make sure to size the connection piping (Figure 17, item 23) to handle
the total flow it must handle.
2. Install a system circulator (supplied by installer) capable of delivering the
proper flow and head as shown.
3. 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 pri-
mary/secondary connection, item 21).
piping shown ensures the boiler loop will have sufficient flow.
For other piping methods, see guidelines on page 15.
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. See Advanced Manual to
configure Boiler Pump to run during DHW demands.
2. DHW as Zone – not applicable to this application.
3. Priority of DHW/Space Heating:
a. DHW Priority – DHW is priority over space heating. Use Priority1
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 set up for Space Heat-
ing (Priority 2). Each input correlates to its respective circulator output.
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)
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
18
COMMERCIAL CONDENSING GAS
(continued)
pipe size shown in Figure 12, page 15
Legend — Figure 17
- — Boiler Manual
FIRED WATER BOILER
Zone valve zoning plus optional DHW piping
For DHW applications, assign DHW inputs to determined Priority (1,
2 or 3). Priority 1 is defaulted to DHW for DHW
3. For more than 3-zones, use Weil-McLain WMZV zone valve controller.
Connect zone valve end switches to a
Priority input, , (default
Connect system circulator to corresponding output.
Use isolation relays if connecting 3-wire zone valve
end switches to the inputs.
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 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.
33 Strainer, recommended.
Items supplied with boiler
Items supplied by others
Priority applications.
Space Heating
Priority 2) to use default settings.
Part number 550-100-180/0917