Weil-McLain 2 Series Manual page 20

®
SlimFit Series 2
Install water piping
Radiant Heating —
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 pri-
mary/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 at least the
on all boiler loop piping (connecting boiler to and from the primary/
secondary connection, item 21).
shown ensures the boiler loop will have sufficient flow. For other
piping methods, see guidelines on page 15.
High limit in system piping
1. Add the recommended high limit control (Figure 19, 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 16.
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 con-
trol 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 47, for instructions on
wiring to circulators.
2. The factory default settings are: all three inputs are set up for Space Heat-
ing ( Priority 2) . Each input correlates to its respective circulator output.
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 circulator)
6 Isolation valves
7 System circulator (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 circulator
20
COMMERCIAL CONDENSING GAS
(continued)
Zone valve zoning –
See Figure 19.
pipe size shown in Figure 12, page 15
Legend — Figure 19
-
FIRED WATER BOILER
primary/
Typical radiant heating system piping plus
optional DHW
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 Heat-
ing 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 External drain/blowdown valve, when used.
33 Strainer, recommended.
Items supplied with boiler
Items supplied by others
— Boiler Manual
Part number 550-100-180/0917