Weil-McLain 550 MBH Nstallation And Operation Manual page 15

®
SlimFit Series 3
Install water piping
ZONE VALVE zoning –
(Shown with optional DHW piping)
This configuration is for zone valve systems using a boiler loop connected
as a secondary circuit off of a primary system loop.
ary 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. Install a system circulator (supplied by installer) capable of delivering
the proper flow and head as shown.
2. 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.
2. DHW as 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.
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.
c. No Priorities – Space heating and DHW can occur
neously. Use only if DHW is a zone in system. Assign DHW
and Space heating to 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 50, for
instructions on wiring to circulators.
2. The factory default settings are: all three inputs are set up for Space
Priority 2)
Heating ( . Each input correlates to its respective circula-
tor output. For DHW applications, assign DHW inputs to determined
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
Part number 550-100-168/0516
COMMERCIAL CONDENSING GAS
(continued)
primary/secondary
See Figure 7.
The primary/second-
the pipe size shown in
ensures the boiler
Legend — Figure 7
-
FIRED WATER BOILER
Zone valve zoning plus optional DHW
piping
simulta-
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
Heating
default settings. Connect system circulator to cor-
responding output.
Use isolation relays if connecting 3-wire zone
valve end switches to the inputs.
12 Boiler circulator
13 Zone valves, typical
20 Make-up water supply
21 Primary/secondary connection
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
Priority input, (default Priority 2)
Space
to use
15