34
420012001500 - 03182024 - Rev. 04
NOTE: In piping applications utilizing a single
zone, it is recommended that the installer
use flow / check valves with weighted seats
at or near the appliance to prevent gravity
circulation.
NOTES:
1. This drawing is meant to show
system piping concept only. Installer
is responsible for all equipment and
detailing required by local codes.
2. The minimum pipe size of DHW piping
should be ¾” diameter and CH piping
should be 1” in diameter.
3. Circulators are shown with isolation
flanges. The alternative is standard
flanges with full port ball valves. Purge
valves can be used with circulator flanges
as an alternative.
4. Install a minimum of 12 diameters of
straight pipe upstream of all circulators.
5. VERY IMPORTANT – Minimum flow rates
outlined in this manual (2 gpm) must be
maintained through the heat exchanger
to minimize short cycling.
Part 4 - Water Piping
ZONE
#1
ZONE
#2
ZONE 1 ZONE 2
CH PUMP
N LG
DHW PUMP
N LG
120VAC INPUT
N LG
LINE VOLTAGE JUNCTION BOX
JUMPER
TRANSFORMER
MAKE-UP
WATER
INCREASE FILL
PRESSURE TO 20PSI
WHEN PIPING
DIRECT TO ZONES
IMPORTANT:
EXPANSION TANK MUST BE ON THE
SUPPLY SIDE IN APPLICATIONS
PIPED DIRECT TO ZONES
M
For direct (not primary / secondary) piping applications, the expansion vessel must be placed on the supply side of the boiler as illustrated.
Placement of flow resticting devices, such as check valves, is prohibited between the boiler return and the expansion vessel. Failure to place the
expansion vessel as instructed, may result in the release of the pressure relief valve, property damage, severe personal injury, or death.
WARNING
6. In a valve-based system, each heating
zone has a zone valve which opens
when that zone calls for heat. Each zone
thermostat is wired to its corresponding
zone valve. Contacts in the zone valves
provide a signal to the boiler to operate
when there is a call for heat.
7. Unit is equipped with built-in primary
pump for the heating loop. This pump
is sized to ensure proper flow rate
through the boiler heat exchanger and
related piping.
8. In direct (not primary / secondary) piping
applications, it is required to increase
fill pressure to 20 psi to ensure proper
system operation.
Figure 27 - TRX110C / TRX150Cwithout Central Heating Circulator
The piping will not support the weight
of the circulators. Refer to the circulator
manufacturer’s instructions to properly
support the circulator. Failure to comply with
these instructions could result in property
damage, severe personal injury, or death.
NOTICE
WARNING
Figure illustrates the basic plumbing
requirements for a TRX110C / TRX150C
boiler installation without an external Central
Heating circulator; the boiler’s internal
circulator delivers flow to the heating system.
Application is limited to zone valve (or non-
circulator) distribution systems with small
flow requirements (e.g. systems requiring no
more than 5 gpm at 9 ft. of head pressure)
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