NTI TRX II Series Installation Start-Up Maintenance page 30

Part 4 - Water Piping
ZONE 1 ZONE 2
TRANSFORMER
JUMPER
ZONE #1
WARNING
For direct (not primary / secondary) piping applications, the
expansion vessel must be placed on the return 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.
NOTICE
Figure illustrates the basic plumbing
requirements for a TRX199C 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 9 gpm at 9 ft. of
head pressure).
WARNING
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.
30
LINE VOLTAGE JUNCTION BOX
CH PUMP DHW PUMP
N G L N G
ZONE #2
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.
120VAC INPUT
L N G L
Figure 19 - Combi Boiler without Central Heating Circulator
M
MAKE-UP WATER
IMPORTANT:
EXPANSION TANK MUST BE ON THE
RETURN SIDE IN APPLICATIONS
PIPED DIRECT TO ZONES
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. For direct (not primary / secondary)
piping applications, it is required to
install the expansion vessel on the return
side of the boiler as illustrated.
420012001300 - Rev. 04 - 031524