The standard pressure relief valve is a Watts 1˝ Model
174A set at 50 psi with a relief capacity of 1,400,000
Btu/h. Maximum allowable working pressure of boiler is
60 psig.
Optional relief valve is 1˝ Watts 174A set at 60 psi with
a relief capacity of 1,621,000 Btu/h.
Optional relief valve is 1˝ Watts 174A set at 30 psi with
a relief capacity of 958,000 Btu/h.
A discharge pipe the same diameter as the pressure
relief valve discharge opening must be rigidly installed
directly onto the pressure relief valve. The discharge
should extend to the floor drain and end approximately
6˝ above drain. Do not install a shut-off valve in
discharge piping. Do not pipe discharge outdoors. Refer
to Fig. 13.
Never cap or plug relief valve opening or discharge
pipe. The discharge pipe must be arranged so as to
prevent scalding of attendants. Follow instructions
supplied with pressure relief valve.
If pressure relief valve is discharging frequently locate
source of problem and correct. Significant amounts of
make-up water will cause mineral deposits in boiler
which may lead to boiler failure. This type of failure is
not covered under warranty.
7.0
Start-up and operating instructions
Do not attempt to start the boiler if you smell gas. If you
smell gas, open windows, do not touch electrical
switches, extinguish any open flame, close all gas
valves immediately. See page 14 for detailed lighting
instructions.
Ensure that boiler is filled with water prior to start-up.
7.1
Pilot and manifold pressure check
Gas supply pressure must not exceed 14˝ w.c. for all
gases.
After checking for gas leakage according to sections
2.4.4, 2.4.5 and 3.0, ensure pilot pressure is between 5˝
and 6˝ w.c. for natural gas and between 8˝ and 10˝ w.c.
for LP with pilot burner operating.
Attach manometer to test port downstream of pilot
valve. Close main burner test firing valve so that only
pilot burner operates. Pilot pressure is factory adjusted
to 5.0˝ w.c. with a supply pressure of 7.0˝ w.c. for
natural gas. Adjust pilot pressure if necessary to
between 5.0˝ and 6.0˝ w.c. and between 8˝ and 10˝ w.c.
for LP. The ionization signal has to be greater than
1
µ
A D.C. (typical 3-5
µ
A D.C.) Re-attach pressure port
and leak test.
After checking pilot pressure, check manifold pressure
with manometer to ensure it is 3.5˝ w.c. Do no operate
the burner at pressures higher than 3.5˝ w.c. Test port
at centre of gas manifold may be used. To open, turn
screw in fitting counterclockwise two turns. To close,
turn screw clockwise until it seats. Leak test pressure
port.
For 2-stage RS boilers, the first stage pressure is
factory preset to 1.3˝ w.c. Do not attempt to readjust it.
Any attempt to readjust this pressure will render the
warranty null and void.
7.2
Boiler wiring
Boiler electrical requirements are 120V, 60 Hz, less
than 12A. Pumps must be powered by separate power
supply.
See wiring diagram in rear of manual and wiring label
on boiler. Viessmann reserves the right to substitute
electrical components as necessary. The boiler wiring
label diagram takes precedence.
All wiring must be properly grounded! Before
attempting to wire the unit, disconnect power supply at
main service panel first. Dedicated ground wire must
be run from boiler to service panel.
All electrical wiring is to be done in accordance with
the latest edition of the National Electrical Code ANSI
/NFPA 70. In Canada use CSA C22.1 Part 1 and/or
local codes.
Caution:
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation. Verify proper operation after
servicing.
7.3
Testing – gas pipe
The boiler and its individual shut-off valve must be
disconnected from the gas supply piping system during
any pressure testing of that system at test pressures in
excess of 14˝ w.c. (3.5 kPa).
The boiler must be isolated from the gas supply piping
system by closing its individual manual shut-off valve
during any pressure testing of the gas supply
11
Fig. 13
Boiler accessories
Pressure relief valve
Air vent
Pressure gauge
faces towards
boiler front
Front of boiler
Flange
