Relief Valve Installation and Piping
The heater is supplied with a Section IV “HV” stamped
relief valve sized for the full input of the unit. The relief
valve assembly is shipped loose and must be mount-
ed directly to the heater outlet. No valve shall be
installed between the heater and the relief valve. The
relief valve shall be mounted with its spindle vertical
(see Fig. 1, 2 and 3 on page 6). Relief valve discharge
piping shall provide no less than the cross sectional
area of the relief valve outlet and must be routed to a
safe point of discharge. Installation must comply with
all national, state and local codes.
Temperature & Pressure Gauge
The temperature and pressure gauge is shipped loose
for field installation and must be installed within 12
inches of the boiler outlet (if possible) in an easily
readable location. Installation must comply with ASME
Section IV as well as all applicable national, state and
local codes.
Hydrostatic Test
Unlike many types of heaters, this heater does not re-
quire hydrostatic testing prior to being placed in
operation. The heat exchanger is ASME certified for
160 psi maximum working pressure. However, Raypak
does recommend hydrostatic testing of the piping con-
13
nections to the heater and the rest of the system prior
to operation. This is particularly true for hydronic sys-
tems using expensive glycol-based anti-freeze.
Raypak recommends conducting the hydrostatic test
before connecting gas piping or electrical supply.
Leaks must be repaired at once to prevent damage to
the heater. NEVER use petroleum-based stop-leak
compounds.
To perform hydrostatic test:
1. Connect fill water supply. With bleed valve open,
fill heater with water. When water flows from bleed
valve, shut off water. Close bleed valve. Carefully
fill the rest of the system, making sure to eliminate
any entrapped air by using high-point vents. Close
feed valve. Test at standard operating pressure for
at least 24 hours.
2. Make sure constant gauge pressure has been
maintained throughout test.
3. Check for leaks. Repair if found.
Flushing/Cleaning of System Piping
Many of the chemicals used to perform this function
will harm the heat exchanger as well as some gaskets
and seals within the unit, causing a non-warrantable
failure. When required, Raypak recommends the boil-
er be isolated from the system piping prior to flushing
or cleaning using any cleaning agent.
Cold Water Operation
Raypak’s Cold Water Protection systems provide func-
tionality to bypass water from the heater discharge to
be mixed with the cooler water returning to the heater
inlet. This is done to elevate the heater inlet tempera-
ture 50ºF (10ºC) or above (user adjustable) within 7
minutes to prevent harmful condensation from forming
in the combustion chamber.
This heater must operate with a stable inlet tempera-
ture at 50ºF (10ºC) or above. Long periods of
operation with temperatures below 50ºF (10ºC) can
excessively cool the products of combustion, resulting
in collection of condensate in the heat exchanger,
combustion chamber and significantly reducing the life
of the equipment.
WARNING:
Pressure relief valve discharge piping
must be piped near the floor and close to a drain to
eliminate the potential of severe burns. Do not pipe
to any area where freezing could occur. Refer to
local codes.
CAUTION:
This boiler requires forced water
circulation when the burner is operating. See Table H
and Table I for minimum and maximum flow rates
and water pump selection. The pump must be
interlocked with the boiler to prevent heater
operation without water circulation.
NOTE:
Minimum pipe size for in/out connections is
1-1/2 NPT for model 300A and 2 NPT for models
400A, 500A, 700A and 850A. Verify proper flow rates
and ∆T as instructed in this manual.
WARNING:
The pressure relief valve must be
installed at the outlet of the boiler. No valve is
permitted to be installed between the boiler and the
relief valve.
NOTE:
The continuous inlet water temperature
must be no less than 50°F.
WARNING:
Damage due to internal condensation
may occur if the heater inlet water temperature does
not exceed 50ºF (10ºC) within 7 minutes of startup.
