20
FUTERA II INSTALLATION AND OPERATION INSTRUCTIONS
Low Water Cutoff
If a boiler is installed above any radiation elements it must
be fitted with a low water cutoff device.
Refer to the 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 flow rates or
return water temperatures less than
125°F,
52°C must be
isolated from these systems to protect the boiler. Figure
13, shows a typical primary/secondary piping system. A
dedicated pump is used to maintain a constant water flow
through the boiler. This boiler pump is sized to overcome
the head loss of the boiler and near-boiler piping system
while supplying the flow rate required to maintain the
desired temperature rise across the boiler heat exchanger.
The system pump is sized to provide the required flow
to the heating system. The boiler piping connections to
the heating system piping must be a maximum 10X pipe
diameters between centers to ensure zero pressure drop
in the primary system. Flow must be properly accounted
for in the design of primary/secondary systems. In order
to prevent boiler(s) short cycling the system flow must be
equal to or higher than the boiler(s) local flow.
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
14 and 14A. The bypass and bypass valve must be sized
the same as the secondary piping. A balancing valve must
also be installed in the supply side of the secondary piping
downstream of the bypass. The 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. The primary and secondary pumps should be
sized to provide the required flow through each system.
The secondary piping connections to the primary system
piping must not be more than 10X pipe diameters apart
to ensure zero pressure drop in the primary system, see
Figure 14.
Multiple Boiler Systems
Systems using multiple boilers can also be installed using
a primary/secondary manifold system, Figure 15.
Piping For Use With Cooling Units
The 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 flow-control valves
or some other automatic means of preventing gravity
circulation of the boiler water during the cooling cycle.