41
perpendicular to the flow direction for the
best flow sensitivity. Do not tighten the switch
by grasping the switch enclosure. Use the
wrenching flats on the bushing only. The turning
radius required for the switch mounting is 3 in.
(80 mm).
o. For flow switch wiring refer to Section VIII
“Electrical” of these instructions.
B. Piping System To Be Employed.
Apex boilers are designed to operate in a closed loop
pressurized system. Minimum pressure in the boiler
must be 20 psi (140 kPa). Proper operation of the Apex
boiler requires that the water flow through the boiler
remain within the limits shown in Table 12 any time the
boiler is firing.
NOTICE
Failure to maintain the flow through boiler within
specified limits could result in erratic operation
or premature boiler failure.
1. Near boiler piping must isolate Apex boiler
from system piping via closely spaced tees
to insure specified flow range through boiler
any time the boiler is firing.
a. The flow rate through the isolated near-boiler
loop is maintained by installer supplied
boiler circulator. See Tables 13A and 13B for
recommended circulators.
b. The flow rate through the isolated near-boiler
loop is completely independent of the flow rate
through the heating system loop(s).
c. The flow rate through the heating system loop(s)
is controlled by installer sized/provided system
loop circulator(s).
d. This piping arrangement can be used either for
space heating-only applications or space heating
with indirect water heater(s) applications.
i.
Space heating only - refer to Tables 13A and
13B and Figure 20 “Near Boiler Piping -
Heating Only” as applicable.
ii.
Space heating plus indirect water heater(s)
– refer to Tables 13A and 13B and Figure 21
“Near Boiler Piping - Heating Plus Indirect
Water Heater” as applicable.
iii.
If piping indirect water heater off boiler
(see Figure 22A), be sure that indirect water
heater and domestic hot water circulator are
sized to maintain flow through boiler within
limits shown in Table 12.
VI. Water Piping and Trim
B. Piping System To Be Employed (continued).
NOTICE
Where it is not possible to install a separate
boiler loop, the system circulator must be
sized to ensure that the flow through boiler
stays within the defined parameters to prevent
overheating when the boiler is fired at it’s full
rated input. Install a flow meter to measure the
flow, or fire the boiler at full rate and ensure the
boiler
Δ
T does not exceed 35°F (19°C).
2. Direct connection of Apex boiler to heating
system, similar to a conventional boiler, is
NOT RECOMMENDED because:
a. The flow rate through system must be the same
as through boiler and fall within limits specified
in Table 12.
b. Pressure drop through entire system must be
known, added to pressure drop through boiler,
and a circulator selected to provide required flow
at total calculated pressure drop.
c. It is often very difficult to accurately calculate
the pressure drop through the system.
d. In replacement installations, it may be nearly
impossible to get an accurate measurement of
piping amount and number of fittings in the
system. If system is zoned, the system flow rate
may drop well below recommended minimum
flow when only a single zone is calling for heat.
C. Standard Installation Requirements.
Observe the following guidelines when making the
actual installation of the boiler piping:
1. Safety Relief Valve (Required)
– The safety
relief valve is packaged loose with boiler and
must be installed in the location shown in Figures
19A, 19B or 19C “Factory Supplied Piping and
Trim Installation”. The safety relief valve must
be installed with spindle in vertical position.
Installation of the safety relief valve must comply
with ASME Boiler and Pressure Vessel Code,
Section IV. The standard factory shipped safety
relief valve is set at 50 psi (340 kPa) on APX425
and APX525 and 60 psi (410 kPa) on APX625,
APX725 and APX825. Optional 80 psi (550 kPa)
and 100 psi (689 kPa) safety relief valve kits are
available. If the safety relief valve is to be replaced,
the replacement valve must have a relief capacity
equal or exceeding the minimum relief valve
capacity shown on the heat exchanger ASME plate.
Also, when replacing the safety relief valve, verify
the temperature and pressure gage meets ASME
requirements for the replacement safety relief valve.
Pipe the safety relief valve discharge to a location
where hot water or steam will not create hazard or
property damage if the valve opens.
Summary of Contents for APEX
Page 57: ...57 VIII Electrical continued Figure 26 Ladder Diagram ...
Page 58: ...58 VIII Electrical continued ...
Page 59: ...59 Figure 27 Wiring Connections Diagram VIII Electrical continued ...
Page 105: ...105 ...
Page 109: ...109 XIII Repair Parts continued APX625 APX725 and APX825 APX825 shown ...
Page 112: ...112 XIII Repair Parts continued APX425 and APX525 ...
Page 114: ...114 XIII Repair Parts continued APX625 APX725 and APX825 ...
Page 122: ...122 ...
Page 123: ...123 ...
