American Standard PFWF071A93ABA Installation Manual page 13

4) The installer of the boiler is required to provide
a low water cutoff switch when installing the
boiler above the distribution system. Consult local
codes which may require a low water cutoff for all
installations regardless of boiler location. The low
water cut off switch should discontinue burner
operation until proper water level is achieved.
5) The return water temperature to the boiler must
be above 110° F. The cases where this boiler is
installed on systems with large volumes of water
(for example - retro fi tted gravity system or low
temperature systems such as radiant fl oor systems),
the installer is required to use one of the methods
of boiler protection described in this manual under
"System Piping Diagrams" to protect the system.
Pipe Connections
a) The threads in the heat exchanger casting
are 1-1/4" NPT female. Supply and Return
nipples that ship with the boiler are 1-1/2" NPT
male x 1-1/4" NPT male. See Figure 2 and
Figure 6.
b) Boiler drain requires installation. See Fig. 6.
6) Install factory provided piping items as shown
in Figure 6. These include the supply water adap-
ter tee, the pressure relief valve, the return water
nipple, the drain adapter, and the drain valve.
▲ ▲
WARNING
!
.
SAFETY HAZARD.
PRESSURE RELIEF VALVE OUTLET MUST BE
ROUTED TO WITHIN 6" OF A FLOOR DRAIN OR
OTHER AREA SAFE FOR DISCHARGE OF HOT
WATER AND SAFE FROM FREEZING. THIS
PIPE MUST BE FULLY 3/4" IN SIZE THE ENTIRE
LENGTH AND IT MUST NOT CONTAIN ANY
RESTRICTIONS, TRAPS, VALVES, PLUGS, OR
CAPS. FAILURE TO FOLLOW THIS WARNING
COULD RESULT IN SERIOUS INJURY, DEATH,
OR PROPERTY DAMAGE.
Head Loss vs.
Flow Chart
for All *PFWF
Models
7) A 3/4" pipe must be routed from the outlet of the
pressure relief valve to the nearest suitable drain.
This pipe is not provided with the boiler.
8) Before connecting the boiler to the hydronic
system, carefully fl ush all the pipes of the system
with water to remove residues or impurities that
could affect the unit's performance.
9) Supply and return water connections are located
on the back of the boiler. The installation of piping
shall be in accordance with National, State and local
codes.
It is advisable to install on-off valves between the
boiler and heating system and on the inlet and outlet
side of all hydronic system components for service.
This allows the boiler or components to be isolated
from the system if necessary.
Characteristics of the water system
In the presence of water harder than 14 grains per gallon,
we recommend the use of suitably conditioned water
in order to avoid possible scaling in the boiler, caused
by hard water, or corrosion produced by aggressive
water. It should be remembered that, because of its
low thermal conductivity, even scaling of just a few mm
thick causes signifi cant overheating of the boiler walls
with consequent serious problems.
Water treatment is indispensable in the case of very
large systems (containing large amounts of water) or
with frequent introduction of replenishing water in
the system. If partial or total emptying of the system
becomes necessary under these conditions, it is advisable
to refi ll it with treated water.
Proper boiler operating pressures
The system pressure when cold should be about 12psi.
For correct operation of the boiler, when hot, its pressure
should be about 18-24 psi.
18-CG03D1-4
13