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Part number 550-100-400/0119
54
Legend — Figure 50
1 Ultra boiler
2 Indirect water heater (DHW), if used
3 Boiler relief valve (see page 9 for piping details)
4 Relief valve discharge piping (see page 9 for details)
5 DHW circulator (see page 56 for suggested sizing)
6 Isolation valves
7 System circulator (see information above for wiring)
8 Diaphragm (or bladder) type expansion tank (see page 56 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
21 Primary/secondary connection (tees no more than 12 inches apart)
22 Optional high limit temperature control, set to protect radiant tubing
23 DHW supply/return
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 Temperature/Pressure gauge
27 DHW relief valve, if used
Items supplied with boiler
Items supplied by others
Figure 50Tpical radiant heatin sstem pipin plus
optional
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 boil-
er return water temperature in radiant heating applications.
2. Connect boiler to system as shown in Figure 50 for typical
radiant heating applications. The primary/secondary piping
shown ensures the boiler loop will have suffi cient fl ow. Size
the system piping and circulator to provide the fl ow and
pressure drop needed for the radiant system.
Use the pipe size shown in Fig-
ure 50 on all boiler loop piping (connecting boiler
to and from the primary/secondary connection,
item 21).
Failure to follow these guidelines could
result in system problems.
3. Adding the recommended high limit control ( Figure 50 ,
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 U-Control.
4. When using a closed-type expansion tank, connect the
expansion tank and make-up water piping as shown in
Figure 4, page 11 .
5. Connect DHW (domestic hot water) piping to indirect stor-
age water heater as shown.
By default, the U-Control Module turns off space
heating during DHW heating (if DHW input is
priority 1). The boiler circulator will turn off, pre-
venting hot water from circulating to the system
(optional timeout setting can be used to override).
The fl ow/check valve shown on the boiler outlet
piping prevents gravity circulation in the boiler
loop during DHW heating.
Overriding the Outdoor Reset function by setting control
to DHW mode when system is intended for space heat-
ing may violate Section 303 of the 2007 Energy Act. See
page 137 for compliance information and exemptions.
6. Controlling the circulators
a. The U-Control can control up to three circulators (boiler
circulator and two others). Refer to Field wiring, begin-
ning on page 30 , for instructions on wiring to circulators.
Install water piping — advanced (continued)
b. The factory default settings are: DHW circulator as Circu-
lator 1, boiler circulator as Circulator 2. See Field wiring
instructions, beginning on page 30 , for details.
®
Series 4
gas-fired water boiler — Boiler Manual
Boiler loop pipe size
Ultra-80, 105
Ultra-155, 230
Ultra-299/310,
399
1”
1¼”
1½”
See CAUTION at left.
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