Weil-McLain SlimFit Manual page 20

SlimFit
™
commercial condensing gas
Install water piping
Radiant heating applications
1. The SlimFit boiler is ideal for use in radiant heating. The SlimFit boiler's
unique heat exchanger design allows it to work well even in condensing
mode. So there is no need to regulate boiler return water temperature
in radiant heating applications.
2. Adding the recommended high limit control (Figure 19, item 22) can
help ensure supply water temperature will not exceed the maximum
allowable for the radiant system. Wire this limit control in either the
manual reset or automatic reset external limit circuit of the Sola.
3. When using a closed-type expansion tank, connect the expansion tank
and make-up water piping as shown in Figure 15, page 16.
4. 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 al-
lowable flow rate range listed in Figure 13, page 15 of this
manual.
5. 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.
Controlling the pumps
6.
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)
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 pump
13 Zone valves, when used (zoning may also be done using manifold-mounted
valve actuators)
20
-
fired water boiler
(continued)
Figure 19
Legend — Figure 19
20 Make-up water supply
21 Primary/secondary connection (tees no more than 8 pipe diameters apart)
22 Optional high limit temperature control, set to protect radiant tubing
25 Systems using high-head pumps 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
NOTE 1:
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 guidelines could result in system problems.
— Boiler Manual
Typical radiant heating system piping
plus optional DHW
Use at least 3-inch schedule 40 pipe on all
boiler loop piping (connecting boiler to and
Part number 550-100-116/0713