21
Cast Iron Condensing Boilers – Installation Manual
FlexCore Stainless Steel Condensing Boilers – Installation Manual
Figure 10 - Typical Single Boiler Piping
(RECOMMENDED)
(Circulator pump must be sized for minimum water
flow rate of boiler, including system pressure drop)
Reverse Return Piping (RECOMMENDED)
Systems using multiple boilers can also be installed
using a reverse return system, Figure 11.
Primary/Secondary Piping
Although acceptable, the system is not as cost effective as
reverse return piping. Figure 12 shows a typical primary/
secondary piping system. A dedicated pump is used to
maintain a constant water flow through the boiler. 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. Systems using multiple boilers can be installed
using a primary/secondary manifold system, Figure 13.
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.
It is essential that following boiler shut off,
the boiler pump continue to operate for
approximately (5) minutes to dissipate the
heat away from the heat exchanger.
PUMP
GATE VALVE
BACKFLOW PREVENTION
DEVICE
THERMOMETER
EXPANSION TANK
PRESURE
RELIEF VALVE
PRESURE
REDUCING VALVE
AQUASTAT
RIOM-0209_A
SYSTEM
RETURN
COLD WATER
MAKE-UP
SYSTEM
SUPPLY
WATER
METER
WM
WM
PUMP
GATE VALVE
BACKFLOW PREVENTION
DEVICE
THERMOMETER
EXPANSION TANK
PRESURE
RELIEF VALVE
PRESURE
REDUCING VALVE
AQUASTAT
RIOM-0209_A
SYSTEM
RETURN
COLD WATER
MAKE-UP
SYSTEM
SUPPLY
WATER
METER
WM
WM
Water Treatment
This boiler was designed to operate in a closed loop
heating system. System fill water must not contain more
than 500 ppm of total dissolved solids, less than 150
ppm chloride concentration and no greater than 300
ppm hardness. Suspended solids such as Magnetite,
Iron Oxides must be flushed from the system prior to
commissioning the boiler(s). The PH level must be
within the 6.5-10 range. Where required, the system
must be protected by the addition of a corrosion inhibitor
per the chemical supplier’s instructions.
For systems requiring glycol for freeze protection use a
glycol/water mix that prevents foaming. Air entrapped
within foam significantly decreases heat transfer and
can result in damage to the heat exchanger. Products
such as DOWFROST, DOWTHERM, UCARTHERM or
an equivalent product must be used to ensure proper
protection to the boiler.
The water used for dilution of concentrated heat transfer
fluids must be distilled, de-ionized, or equivalently clean
as stated above. De-ionized water by itself can be
aggressive torwards many metals, but is perfectly safe
when used for dilution of DOWFROST, DOWTHERM or
UCARTHERM as specified by the manufacturer.
FAILURE TO ENSURE PROPER WATER QUALITY
CAN RESULT IN DAMAGE TO THE BOILER(S)
VOIDING THE WARRANTY.
Water Meter
Make-up water introduced into a closed system due
to system leaks can negatively affect the long term
reliability of the heating sytem resulting in abnormal
boiler water quality. It is recommended that a water
meter be installed in the system make-up line. If make-
up is recorded, the leaks must be found and repaired.
Pump Requirements
This boiler requires a continuous minimum water flow
for proper operation. The system pump must be sized
to overcome the head loss of the boiler and the heating
system in order to achieve the required temperature rise.
If the system contains hydronic antifreeze this must be
considered when sizing the pump. The temperature rise
across the boiler must never exceed
100°F, 55.6°C.
Low Water Cutoff
Each boiler comes equipped with a factory installed low
water cutoff.
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.
