35110331-01 - 5/20
PHTM II
Installation, Operating & Service Instructions
General System Piping Precautions
WARNING
Asphyxiation Hazard.
• Failure to properly pipe boiler could cause
improper operation and damage to boiler or
building resulting in severe personal injury,
death or substantial property damage.
• Protect gas ignition system components
from water (drippings, spraying, rain, etc.)
during boiler operation and service (circulator
replacement, condensate trap, control
replacement etc).
• Oxygen contamination of boiler water will cause
corrosion of iron and steel boiler components
and could lead to premature boiler failure.
Warranty does not cover problems caused by
oxygen contamination of boiler water or scale
(lime) build-up caused by frequent addition of
water.
• Maintain clearances to system piping per
Figure 5-1.
Standard Piping Components
1. Safety relief valve (required).
A. Shipped loose in miscellaneous parts
carton (30 psi).
B. Pipe outlet of safety relief valve to location
where water or steam will not create a
hazard or cause property damage if valve
opens. (The end of discharge pipe must
terminate in unthreaded pipe.)
C. If safety relief valve discharge is not piped to
drain, it must terminate within 6 in. (150 mm)
of floor.
D. Do not route discharge piping through an
area that is prone to freezing temperature.
E. Termination of safety relief valve must be in an
area where it is not likely to become plugged
by debris.
CAUTION
Toxic Material.
The heat transfer medium must be water or
other nontoxic fluid having a toxicity rating or
Class of 1, as listed in Clinical Toxicology of
Commercial Products, 5th edition.
10 Heating System Piping
!
!
2.
WARNING
Burn Hazard.
Safety relief valve discharge piping
must be piped near floor to eliminate
potential of severe burns. Do not
pipe in any shut-off valves between:
1. Safety relief valve and boiler
2. Safety relief valve and discharge.
Union may be installed in safety relief valve
piping.
Pump (required)
Boiler loop pump is factory installed inside
boiler cabinet. At least one additional pump is
required on system side.
3. Expansion tank (required)
A. If this boiler is replacing an existing boiler with
no other changes in system, old expansion
tank can generally be reused.
B. If expansion tank must be replaced, consult
expansion tank manufacturer's literature for
proper sizing.
C. If using antifreeze, account for additional
expansion of glycol solution when sizing
an expansion tank. In a typical residential
heating system, a glycol mixture has an
expansion rate of 1.2 times that of water
alone, therefore a tank for an anti-freeze
system should be at least 1.2 times
greater in size.
4. Fill valve (required)
A. Either a manual or automatic fill valve may
be used, but a manual valve is preferred
because it eliminates unmonitored additions
of make-up water to the system.
B. Ideal location for fill valve is at expansion
tank.
If using antifreeze with automatic fill valve,
C. it is recommended to install a water meter
to monitor make-up water. Antifreeze
concentration will decrease as make-up water
is added. If using antifreeze, local codes often
require a backflow preventer or disconnect
from city water.
!
F. If replaced, replacement must have a setting
less than or equal to maximum allowable
working pressure (MAWP) shown on ASME
data plate located on left side of heat
exchanger.
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