Weil-McLain 550 MBH Nstallation And Operation Manual page 16

®
SlimFit Series 3
Install water piping
Zoning with zone valves — alternate
High-flow-rate/high-head-loss DHW
circuits
See Figure 8.
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 8. 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 8, 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
Figure 4, page 13 on all boiler loop piping (connecting boiler
to and from the primary/secondary connection, item 21).
loop will have sufficient flow. For other piping methods,
see guides on page 13.
Expansion Tank required
1. Provide a system expansion tank following the guidelines on page 14.
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 50, for
instructions on wiring to circulators.
1
SlimFit boiler
2 Indirect water heater (DHW), if used
3 Boiler relief valve (see page 12 for piping details)
4 Relief valve discharge piping (see page 12 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 14 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
16
COMMERCIAL CONDENSING GAS
(continued)
the pipe size shown in
ensures the boiler
-
FIRED WATER BOILER
Zone valve zoning plus optional DHW piping
2. The factory default settings are: all three inputs are set up for
Space Heating (Priority
circulator output. For DHW applications, assign DHW inputs to
determined Priority (1, 2 or 3). Priority 1 is defaulted to DHW for
DHW Priority
3. For more than 3-zones, use Weil-McLain WMZV zone valve
controller.
Connect zone valve end switches to a
Priority input, , (default
settings. Connect system circulator to corresponding
output.
Use isolation relays if connecting 3-wire zone valve
end switches to the inputs.
Legend — 8
12 Boiler circulator
13
Zone valves, typical
20 Make-up water supply
21 Primary/secondary connection
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 Boiler drain valve, ¾" or larger
31 Install a union on the boiler supply and return connections as close as pos-
sible to the boiler to allow disconnection for service when required.
Items supplied with boiler
Items supplied by others
—
Boiler Manual
2). Each input correlates to its respective
applications.
Priority 2)
Part number 550-100-168/0516
Space Heating
to use default