Dunkirk XEB-4 Installation, Operation & Maintenance Manual page 11

4�2 Supply and Return Requirements
• Install radiation units (panels, radiators or cabinets) and
supply and return mains first then make connections at
boiler.
• Verify clean water supply is available when connecting
cold water supply to water valve. Install sand strainer at
pump when water supply is from well or pump.
• Provide low water cutoff device when boiler is installed
above radiation level or as required by the Authority
having jurisdiction, either provide as part of boiler
or at time of boiler installation. Periodic inspection
is necessary, as is flushing of float type devices, per
manufacturers specific instructions. Refer to Figures 3
& 4 for minimum height for installation of LWCO. Refer
to parts manual for LWCO kit. When using LWCO other
than kit listed in parts manual follow specific LWCO
manufacturer instructions.
• Boiler used in connection with refrigeration systems
shall be installed so chilled medium is piped in parallel
with heating boiler with appropriate valves to prevent
chilled medium from entering heating boiler.
See Figure 5.
• Boiler connected to heating coils located in air handling
units exposed to refrigerated air circulation, piping
system shall be equipped with flow control valves or
other automatic means to prevent gravity circulation of
boiler water during cooling cycle.
Figure 5 - Piping Arrangements For Boiler When
Used In Connection With Refrigeration
System
4 - CONNECTING SUPPLY AND RETURN PIPING
!
WARNING
Asphyxiation hazard! Gradual flueway blockage
resulting from condensate induced corrosion may
block boiler passages, resulting in carbon monoxide
and or flame rollout. Install bypass piping if return
temperature is under 130°F. Failure to follow these
instructions could result in death or serious injury.
Low Design Water Temperature Systems (Below
150°F) And Large Water Content Systems
Condensation is corrosive and can eventually cause severe
damage to boiler and venting system.
• Minimum design return water temperature to prevent
condensation in boiler and venting is 130°F. Minimum
high limit setting is 150°F.
• Boiler used in heating systems where design water
temperatures below 150°F are desired (e.g. radiant floor
heating), a 3-way or 4-way mixing valve or suitable
alternative is required to prevent low temperature return
water from entering boiler. When using mixing valve,
follow manufacturer's installation instructions.
• Boiler connected to system having large water content
(such as former gravity system), suggest use of bypass
piping. See Figure 6.
Figure 6 - Bypass Piping
11
Adjust two throttling valves to maintain at
least 130° F (54° C) in boiler return.
PN 240013099 Rev. A [08/15/2020]