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6A
Hydronic piping
System water piping methods
The Noble Fire Tube is designed to function in a closed loop
pressurized system not less than 12 psi (Non-metallic system
piping must have an oxygen barrier to be considered a closed
loop).
A temperature and pressure gauge is included to
monitor system pressure and outlet temperature and should
be located on the boiler outlet.
For boiler only models, it is important to note that the boiler
has a minimal amount of pressure drop and must be figured
in when sizing circulators.
Each installation must have an air elimination device, which
will remove air from the system. Install the boiler so the
gas ignition system components are protected from water
(dripping, spraying, etc.) during appliance operation for
basic service of circulator replacement, valves, and others.
Observe a minimum of a 1/4 inch clearance around all
un-insulated hot water pipes when openings around the
pipes are not protected by non-combustible materials.
Low water cutoff device
On a boiler installed above radiation level, some states and
local codes require a low water cutoff device at the time of
installation.
Chilled water system
If the boiler supplies hot water to heating coils in air handler
units, flow control valves or other devices must be installed to
prevent gravity circulation of heater water in the coils during
the cooling cycle. A chilled water medium must be piped in
parallel with the heater.
Freeze protection
Freeze protection for new or existing systems must use
glycol that is specially formulated for this purpose. This
includes inhibitors, which prevent the glycol from attacking
the metallic system components. Make certain to check that
the system fluid is correct for the glycol concentration and
inhibitor level. The system should be tested at least once
a year and as recommended by the producer of the glycol
solution. Allowance should be made for the expansion of the
glycol solution in the system piping.
Use only inhibited propylene glycol
⚠WARNING
solutions, which are specifically formulated
for hydronic systems. Ethylene glycol is
toxic and can attack gaskets and seals used
in hydronic systems.
Heating fluid and Domestic Hot Water
(DHW) piping (Combi only)
The diameter of the heating fluid (hot boiler water) and for
combi models only, DHW piping will depend on the model
number and size of the water heater being installed.
Installation & Service Manual
™
F I R E T U B E
General piping information
All boiler piping must contain an oxygen
IMPORTANT
barrier. This will help prevent any excess
oxygen from entering the system.
Basic steps are listed below along with illustrations on the
following pages (FIG.'s 6-2 through 6-10), which will guide you
through the installation of the Noble Fire Tube.
1. Connect the system return marked "Boiler Inlet".
2. Connect the system supply marked "Boiler Outlet".
3. Install purge and balance valve or shutoff valve and drain
on system return to purge air out of each zone.
4. Install a backflow preventer on the cold feed make-up
water line.
5. Install a pressure reducing valve on the cold feed make-
up water line, (15 psi nominal). Check temperature and
pressure gauge (shipped separately), which should read a
minimum pressure of 12 psi.
For boiler models only, install a circulator as shown in the
piping diagrams on the following pages in this section.
Make sure the circulator is properly sized for the system
and friction loss.
6. Install a system pump if necessary as shown on the piping
diagrams in this section.
properly sized for the system and friction loss.
7. Install an expansion tank on the system supply. Consult the
tank manufacturer's instruction for specific information
relating to tank installation. Size the expansion tank for the
required system volume and capacity.
8. Install an air elimination device on the system supply.
9. Install a drain valve at the lowest point of the system.
Note: The boiler cannot be drained completely of water
without purging the unit with an air pressure of 15 psi.
10. This appliance is supplied with a relief valve sized in
accordance with ASME Boiler and Pressure Vessel Code,
Section IV ("Heating Boilers"). Pipe the discharge of the
safety relief valve to prevent injury in the event of pressure
relief. Pipe the discharge to a drain. Provide piping that is
the same size as the safety relief valve outlet. Never block
the outlet of the safety relief valve.
11. Install a field supplied strainer to prevent damage to the
heat exchanger caused by debris entering from the system
piping. When installing in a pre-existing system, a strainer/
filter capable of removing debris left in the system is
recommended.
See the *piping illustrations included in this section, FIG.'s 6-2
through 6-10 for suggested guidelines in piping the Noble Fire
Tube with either zone valves or circulator pumps.
*Please note that these illustrations are
NOTICE
meant to show system piping concept only,
the installer is responsible for all equipment
and detailing required by local codes.
Make sure the circulator is
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