Dunkirk XEB-3 Installation, Operation & Maintenance Manual page 12

If you are installing an entire new heating system,first install all of
your radiation units (panels, radiators or cabinets) and the Supply
and Return Mains - then make the connections at the boiler.
In connecting the cold water supply to the water vane, make sure
that a clean water supply is available. When the water supply is from
a well or pump, a sand strainer should be installed at the pump.
A hot water boiler installed above radiation level must be equipped
with a low water cutoffdevice. A periodic inspection is necessary, as
is flushing of float type devices, per manufacturers specific instruc-
tions.
When the boiler is used in connection with refrigeration systems
it shall be installed so that the chilled medium is piped in parallel
with the heating boiler with appropriate vanes to prevent the chilled
medium from entering the heating boiler (Figure 7).
If the boiler is connected to heating coils located in air handling
units where they may be exposed to refrigerated air circulation, the
piping system shall be equipped with flow control valves or other
automatic means to prevent gravity circulation of the boiler water
during the cooling cycle.
Low Design Water Temperature Systems (Below 140 ° F)
And Large Water Content Systems:
Significant condensation may form in this boiler and/or
the venting system if the boiler is operated with return
temperatures of less than 120° E
This condensation is corrosiveand can eventuallycause severedam-
age to the boiler and venting system. The minimum design return
water temperature to prevent this condensation in the boiler and
venting is 120°EThe minimum high limit setting is 140°E
If the boiler is to be used in a heating system where design water
temperatures below 140°Fare desired (e.g. radiant floor heating),
a 3-way or 4-way mixing vane or suitablealternative is required
to prevent low temperature return water from entering the boiler.
When using a mixing vane, followthe manufacturer's installation
instructions.
If the boiler is to be connected to a system having a large water con-
tent (such as a former gravity system), it is suggested to use bypass
piping shown in Figure 8.
Figure 7 - Piping Arrangements For Boiler When Used In
Connection With Refrigeration System
VALVES A & B_OPENFORHEATmNG; CLOSEDFORCOOLING
VALVES C & D - CLOSED FORHEATING;OPENFORCOOUNG
TOSYSTEM
Figure 8 - Bypass Piping
Front
Return From System
Throttling
Thermometer
Aquastat Water To System
Feed
Fi_Rro_ With
Air Purger
[ Adi_stthe two th_ttli_g valves to maintain at leas_i20_F i:nthe boiler reLum