Weil-McLain SlimFit Manual page 21

SlimFit
™
commercial condensing gas
Install water piping
Chilled water systems — primary/secondary
piping
1. Install boiler so that chilled medium is piped in parallel with the heating
boiler. Use appropriate valves to prevent chilled medium from enter-
ing boiler. See Figure 20 for typical installation of balancing valve and
check valve.
2. The space heating system may be zoned with pumps if a separate pump
is supplied for the chilled water loop.
If antifreeze is used in the system, consider the effects of an-
tifreeze on pump sizing and DHW performance. Some local
codes may require double-wall DHW heat exchanger design.
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.
3. Connect DHW (domestic hot water) piping to indirect storage water
heater as shown. Connect from the DHW tank aquastat to the DHW
terminals on the SlimFit boiler.
DHW tanks piped using this arrangement need to be sized for
the required load, with a DHW pump selected to provide a
flow rate through the boiler and tank that is within the allow-
able flow rate range listed in Figure 13, page 15 of this manual.
4. DHW priority
— Set the Sola control for the desired DHW priority
mode. Set the boiler pump to be OFF during DHW — it is not needed.
The flow/check valve shown on the boiler outlet piping prevents gravity
circulation in the boiler loop.
5. Controlling the pumps
a. The Sola can control up to three pumps. In this application, set the
Sola control to operate the boiler pump, system pump and DHW
pump.
b. Refer to Field wiring, beginning on page 51, for instructions on
wiring to pumps.
c. The factory default settings are:
Pump A — Boiler pump
Pump B — System pump
Pump C — DHW pump.
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 pump
6 Isolation valves
7 System pump (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
Part number 550-100-116/0713
-
fired water boiler
(continued)
Figure 20
Legend — Figure 20
11 Purge/drain valves
12 Boiler pump
13 Zone valves, typical
15 Closed-type expansion tank
16 Water chiller
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)
25 Systems using high-head pumps require a
bypass pressure regulator to prevent damage
to control valves.
— Boiler Manual
Chilled water system plus optional DHW
piping — primary/secondary piping
26 External drain/blowdown valve, when used
33 Strainer, recommended
Items supplied with boiler
Items supplied by others
Use at least 3-inch
NOTE 1:
schedule 40 pipe
on all boiler loop piping (connecting boiler to and
from the primary/secondary connection,
item 21). Pipe sizing is based on a temperature rise
of 30°F, corresponding to the recommended
maximum flow rate. Failure to follow these guide-
lines could result in system problems.
21