Weil-McLain SlimFit 2 Series Manual page 18

™
SlimFit
COMMERCIAL CONDENSING GAS
Install water piping
Radiant Heating — Zone valve zoning –
secondary (Shown with optional DHW piping)
The SlimFit boiler is ideal for use in radiant heating. The unique heat
exchanger design allows it to work well even in condensing mode. There
is no need to regulate boiler return water temperature in radiant heating
applications. 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. Apply this configuration for typical radiant heating applications.
2. Size the system piping and circulators to provide the flow and pressure
drop needed.
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).
will have sufficient flow. For other piping methods, see guides
on page 13.
High limit in system piping
1. Add the recommended high limit control (Figure 10, item 22) to help ensure
supply water temperature will not exceed the maximum allowable for the
radiant system.
2. Wire the limit control to either the manual reset or automatic reset external
limit circuit of the Control.
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— Not recommended for this application.
3. Priority of DHW/Space Heating:
a. DHW Priority – DHW is priority over space heating. Use Priority
1 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 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 45, for instruc-
tions 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
12 Boiler circulator
18
-
FIRED WATER BOILER
(continued)
See Figure 10.
the pipe size shown in
ensures the boiler loop
Legend — 10
—
Boiler Manual Series 2
primary/
Typical radiant heating system piping plus
optional DHW
2. The factory default settings are: all three inputs are set up
for Space Heating (
respective circulator output. For DHW applications, assign
DHW Input(s) to determined Priority (1, 2, or 3). Priority
1 is defaulted to DHW for DHW Priority applications.
3. For more than 3-zones, use Weil-McLain WMCR zone Circ
controller.
Connect zone valve end switches to a Space
Heating Priority input, (default Priority 2) to
use default settings Connect system circulator
to corresponding output.
Use isolation relays if connecting 3-wire zone
valve end switches to the inputs.
13 Zone valves, when used (zoning may also be done using manifold-mounted valve
actuators)
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
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
Priority 2) . Each input correlates to its
Part number 550-100-162/0815