Weil-McLain Ultra Commercial Installation And Start-Up Manual page 19

COMMERCIAL GAS
Install water piping
Radiant heating applications
1. The Ultra boiler is ideal for use in radiant heating. The Ultra
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. Connect boiler to system as shown in
heating applications. The primary/secondary piping shown ensures
the boiler loop will have sufficient flow. Size the system piping and
circulator to provide the flow and pressure drop needed for the
radiant system.
3. Adding the recommended high limit control (
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 U-Control.
4. When using a closed-type expansion tank, connect the expansion
tank and make-up water piping as shown in Figure 7, page 15.
5. Connect DHW (domestic hot water) piping to indirect storage
water heater as shown.
If DHW input is priority 1: With factory default, on a
call for DHW heating, the U-Control turns circulator 1
(DHW) and circulator 4 (boiler) ON and turns circula-
tors 2 and 3 OFF (so there is no space heating during
DHW operation). For the system shown in Figure 8, you
can set the U-Control to turn the boiler circulator off
during DHW heating. It is not needed. (The flow/check
valve shown on the boiler outlet piping prevents gravity
circulation in the boiler loop.)
6. Controlling the circulators
a. The U-Control can control up to four circulators (boiler cir-
culator and three others). Refer to Field wiring, beginning on
page 51, for instructions on wiring to circulators.
b. The factory default settings are: DHW circulator as Circula-
tor 1, system circulator as Circulator 2, and boiler circulator
as Circulator 4. See Field wiring instructions, beginning on
page 51, for details. (
)
1 Ultra boiler
2 Indirect water heater (DHW), if used
3 Boiler relief valve (see page 13 for piping details)
4 Relief valve discharge piping (see page 13 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 15 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
13 Zone valves, when used (zoning may also be done using
manifold-mounted valve actuators)
20 Make-up water supply
Part number 550-100-086/0809
-
FIRED WATER BOILER
(continued)
Figure 11 for typical radiant
Figure 11, item 22)
Legend — Figure 11
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 possible to
the boiler to allow disconnection for service when required.
Items supplied with boiler
Items supplied by others
NOTE 1:
connection, item 21). Pipe sizing is based on a temperature rise of 30°F, corresponding
to the recommended maximum flow rate. Use only primary/secondary piping as shown.
Failure to follow these guidelines could result in system problems.
— Boiler Manual
Typical radiant heating system piping plus
optional DHW
Use at least the following pipe sizes on all boiler loop piping
(connecting boiler to and from the primary/secondary
19