Water Connections; Manifold Pressure - Viessmann Vitogas 050 Rs Series Installation & Service Manual

B
Gas
A
supply
Manual
Redundant Combination
gas shut-
automatic regulator and
off valve
gas valve automatic gas
valve

Manifold pressure

test port
Fig. 8
Gas valve leak test
Pilot gas pressure (5˝) regulator RV-10
Pilot gas valve ITT
Pilot gas pressure test port
Reducing
elbow
Pilot manual
shut-off valve
Reducing
bushing
Tee
Union
Manual gas
shut-off valve
Inlet
pressure
test port
1
⁄ ˝ NPT
8
Gas burner manifold
Fig. 9
Gas control assembly
3.0 Gas valve leakage test
Maximum inlet pressure for all gases 14˝ w.c.
This is a test for checking the tightness of closure of the
gas safety shut-off valves. It should be performed by
qualified personnel during the initial start-up of a burner
system, or whenever the valve is replaced. It is
recommended that this test also be included in
scheduled inspection and maintenance procedures. For
a periodic inspection test, follow steps 1, 3, 4, 5, 8, 9,
10, 12, 13, 16 and 17.
1. De-energize the control system to ensure that there
is no power to the safety shut-off valves (B) and
(C), shown in Fig. 8.
2. Close the upstream manual gas valve (A).
3. Make sure the manual test valve (F) is closed in the
leak test tap assembly (D).
4. Remove the leak test tap plug and connect the test
apparatus to the leak tap (D).
5. Close the downstream manual gas valve (E).
6. Open the upstream manual gas valve (A).
7. Run the safety shut-off valves (B) and (C) to their
fully open positions (through the safety system);
then immediately de-energize the system to close
the valves.
1
8. Immerse a ⁄ ˝ tube vertically
4
of water.
8
1
⁄ ˝ flexible
4
C
Leak test
tubing
tap
D
1
⁄ ˝ aluminum
4
E
or copper
tubing
1
⁄ ˝
2
Cut at 45°
angle
Jar or glass
with water
1
⁄ ˝ NPT
8
Automatic gas
valve
Main gas valve
and regulator
Pressure test port
1
⁄ ˝ NPT
8
90° street elbow
Manual test
firing valve
Union
1
⁄ ˝ (12.7mm) into a jar
2
Adjustable high limit sensor bulb
Manual reset high limit sensor bulb
F
Test
valve
Thermometer
Fig. 10
5-point boiler well
9. Slowly open the test valve (F).
10. When the rate of bubbles coming through the water
stabilizes, count the number of bubbles appearing
during a 10 second period. Each bubble appearing
during a 10 second period represents a flow rate of
approximately 0.001 ft
To meet all U.S. requirements, leakage must not
exceed the values given below.
Gas valve
size (in.)
1, 1
Following the test:
11. Close the upstream manual gas valve (A).
12. Close the test valve (F), remove the test apparatus,
and replace the leak test tap plug (D).
13. Open the upstream manual gas valve (A) and
energize the safety shut-off valves (B) and (C).
14. Test with soap bubbles to ensure that there is no
leak at the test tap (D).
15. De-energize the safety shut-off valves (B) and (C).
16. Open the downstream manual gas valve (E).
17. Restore the system to normal operation.
4.0 Water connections (see Figs. 11, 15, 23, 24, 25)
The 2˝ NPT supply and return water connections must
be on the same side of the boiler (right side is
standard). Use isolation valves for service purposes.
The length of 2˝ pipe should be limited to the distance
from the boiler to the main headers which will usually be
larger than 2˝ diameter pipe. This distance should be
kept as short as possible. Larger diameter pipe can be
used to connect the boiler to the main supply and return
headers. Use standard friction loss methods for
calculating pipe sizes.
4.1 Low water cut-off
An approved low water cut-off device must be supplied
and installed by the mechanical contractor (see Fig. 11).
Do not install shut-off valve between low water cut-off
and boiler.
Attach to mid panel with sheet
metal screw
Install cable clamp to secure high
limit capillaries in well
3 /h (27 cm
Allowable
leakage
1
⁄ 353 cm 3 /h
4
3 /h).
No. of bubbles
per 10 sec.
13