Water flow switch
A water flow switch is factory installed in the outlet piping
on all heating boilers. The flow switch must prove water flow
before a trial for ignition can begin. The flow switch requires
a minimum flow of 26 GPM to make the flow switch and
start burner operation. A water flow switch meets most code
requirements for a low water cutoff device on boilers requiring
forced circulation for operation. A fault message,
Flow Sw/
LWCO
will be indicated in the Operator Interface on a low
water flow condition as sensed by the flow switch.
Low water cutoff
If this boiler is installed above radiation level, a low water
cutoff device must be installed at the time of boiler installation.
An electronic low water cutoff is available as a factory supplied
option on all models. The low water cutoff should be inspected
every 6 months. A fault message,
Flow Sw/LWCO
will be
indicated in the Operator Interface on a low water condition
as sensed by the low water cutoff.
Relief valve
This unit is supplied with a relief valve(s) sized in accordance
with ASME Boiler and Pressure Vessel Code, Section IV
(“Heating Boilers”). The relief valve(s) is installed in the
vertical position and mounted in the hot water outlet. No
valve is to be placed between the relief valve and the unit.
To prevent water damage, the discharge from the relief valve
shall be piped to a suitable floor drain for disposal when relief
occurs. No reducing couplings or other restrictions shall be
installed in the discharge line. The discharge line shall allow
complete drainage of the valve and line. Relief valves should
be manually operated at least once a year.
CAUTION
Avoid contact with hot discharge water.
Heating boiler installations
Piping of the boiler system
The drawings in this section show typical boiler piping
installations, see FIG.’s 5-3 through 5-7. Before beginning
the installation, consult local codes for specific plumbing
requirements. The installation should provide unions and
valves at the inlet and outlet of the boiler so it can be isolated
for service. An air separation device must be supplied in the
installation piping to eliminate trapped air in the system.
Locate a system air vent at the highest point in the system.
The system must also have a properly sized expansion tank
installed. Typically, an air charged diaphragm-type expansion
tank is used. The expansion tank must be installed close to the
boiler and on the suction side of the system pump to ensure
proper operation.
CAUTION
The boiler system should not be operated at
less than 12 PSIG.
Hot water piping must be supported by suitable hangers or
floor stands,
NOT
by the boiler. Copper pipe systems will be
subject to considerable expansion and contraction. Rigid pipe
hangers could allow the pipe to slide in the hanger resulting in
noise transmitted into the system. Padding is recommended on
rigid hangers installed with a copper system. The boiler pressure
relief valve must be piped to a suitable floor drain. See the
Relief
Valve
section on this page.
CAUTION
A leak in a boiler “system” will cause the
“system” to intake fresh water constantly,
which will cause the tubes to accumulate a
lime/scale build up. This will cause a non-
warrantable failure.
Water connections
All boilers have four inch (4") ASME flanged iron pipe inlet
and outlet connections. Installed piping to and from the boiler
must be a minimum of 4 inches (4") in diameter.
CAUTION
Field installed reducing bushings must not
be used.
Any reduction in pipe size may decrease flow resulting in high
water temperatures, boiler noise, flashing to steam, and non-
warrantable heat exchanger damage.
Boiler circulator requirements
This is a low mass, high efficiency hot water boiler which
must have adequate flow for quiet, efficient operation. Pump
selection is critical to achieve proper operation. A pump should
be selected to achieve proper system design water temperature
rise. Pipe diameter and length are critical to ensure proper flow
through the boiler. A System Temperature Rise Chart (Table 5B
on page 34) is provided to assist in proper pump selection. This
table provides GPM and boiler head-loss at various temperature
rises for each model based on Btu/hr input. Temperature rise
is the difference in boiler inlet temperature and boiler outlet
temperature while the boiler is firing at full rate.
Example:
The boiler inlet temperature is 145°F (63°C) and the
boiler outlet temperature is 180°F (82.2°C). This means that
there is a 35°F (2°C) temperature rise across the boiler. The
boiler temperature rise is visible in the Operator Interface on the
boiler’s front control panel.
26
5
Water connections
Installation & Operation Manual
*Please note that these illustrations are
meant to show system piping concept only,
the installer is responsible for all equipment
and detailing required by local codes.
NOTICE