Instruction manual
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Pump Requirements (Primary/Secondary)
 is low mass boiler requires a continuous minimum water  ow 
for proper operation.   e boiler pump must be sized to overcome 
the head loss of the boiler and the near piping in order to achieve 
the required temperature rise. Table 7 provides the heat exchanger 
pressure drop and temperature rise  gures.  e temperature rise 
across the boiler must never exceed 35°F, 19.4°C. 
  A temperature rise outside of the range listed in Table 
7 indicates that the  ow rate through the heat exchanger 
is incorrect which will damage the heat exchanger 
voiding the warranty!  e maximum allowable 
temperature rise is 35°F, 19.4°C. 
   e maximum allowable  ow rate through a LCD 
boiler with copper heat exchanger is 92 GPM, 
5.8 L/s on 225-1200 models and 115 GPM, 
7.3 L/s on 1480 to 2300 models.  e cupro-nickel 
heat exchanger allows for 100 GPM, 6.3 L/s on 225 
to 1200 models and 125 GPM, 7.9 L/s on 1480 to 
2300 models. 
Low Water Cuto 
If a boiler is installed above any radiation elements it must be   ed 
with a low water cuto device. 
Refer to wiring diagram supplied with the boiler/water heater for 
proper wiring connections.
Expansion Tank & Air Separator
An expansion tank or other means to control thermal expansion 
must be installed in the heating system. An expansion tank must 
be installed close to the boiler on the suction side of the pump. An 
air scoop and automatic air vent must also be installed to eliminate 
air trapped in the system.
Primary/Secondary Piping
Boilers connected to heating systems using zone valves, zone pumps, 
or systems that have excessive  ow rates or return water temperatures 
less than 125°F, 52°C must be isolated from these systems to protect 
the boiler.
Variable Water Flows
Figure 11 shows a typical primary/secondary piping system. A 
dedicated pump is used to maintain a constant water  ow through 
the boiler.  is boiler pump is sized to overcome the head loss of 
the boiler and near piping while supplying the  ow rate required 
to maintain the desired temperature rise across the boiler heat 
exchanger.   e system pump is sized to provide the required  ow 
to the heating system. 
Low Return Water Temperatures
To prevent the problems associated with condensation of the 
products of combustion due to low return water temperatures a 
primary/secondary piping system with a bypass and bypass valve 
must be installed, see Figure 12 and 12A.  e bypass and bypass 
valve must be sized the same as the boiler piping. A balancing valve 
must also be installed in the supply side of the boiler piping 
downstream of the bypass.   e balancing valve should be adjusted 
to divert some of the heated discharge water into the return water 
until the required inlet water temperature is achieved.  e primary 
and secondary pumps should be sized to provide the required  ow 
through each system. 
Multiple Boiler Systems
Systems using multiple boilers can also be installed using a primary/
secondary manifold system, Figure 13.
Piping For Use With Cooling Units
 e boiler, when used in connection with a refrigeration system, 
must be installed so the chilled medium is piped in parallel with 
the boiler. Appropriate valves must be used to prevent the chilled 
water from entering the boiler.
When a boiler is connected to a heating coil that may 
be exposed to refrigerated air from an air handling device, the piping 
system must be equipped with  ow-control valves or some other 
automatic means of preventing gravity circulation of the boiler water 
during the cooling cycle.










