Check Diaphragm Expansion Tank And System Pressure; Check Functioning Of Safety Valves - Viessmann VITODENS 100-W WB1B Series Installation And Service Instructions Manual

Initial Start-up, Inspection and Maintenance
Steps
(continued)
Start-up and Maintenance
Start-up and Maintenance
Start-up and Maintenance
60

19. Check diaphragm expansion tank and system pressure

Perform check on the system when
cold.
1. Drain boiler/system and reduce
pressure until the manometer
reading is "0".
2. If the nitrogen pressure of the
precharged expansion tank is
less than the static pressure of the
system, inflate membrane pressure
to slightly exceed pressure of
system.
The static pressure required at the
tank is based upon the static
height of the system. The system
fill pressure value must be equal to
the expansion tank pressure value
at approx. 60º F / 15.6º C.
3. Top up with water until filling
pressure is higher than the
inlet pressure of the diaphragm
expansion tank.
4. When starting up the system
for the first time, mark this value
as the minimum filling pressure on
the manometer.

20. Check functioning of safety valves

Ensure proper operation of low water
cut-off(s) (if applicable), pressure
relief valve, and pump(s).
Check pressure gage, air vent and
pressure relief valve. Ensure that
pressure relief valve does not leak and
that it operates in accordance with
information provided by the original
manufacturer.
Refer to maintenance instructions
supplied with low water cut-offs,
pumps, etc.
Example
Static head of 33 ft. / 10 m
(distance between boiler and
topmost heat emitter surface)
corresponds to a static
pressure of 1 bar / 15 psig.
With the system cold, the filling
pressure must be approx. 3 psig
higher than the static pressure.
Max. boiler
operating pressure............ 45 psig
Min. boiler
operating pressure....14 to 23 psig
Pressure relief valve.......... 30 psig
A lower manometer reading
usually indicates loss of water due
to leakage. All leaks must be
repaired.
Flush float water type low water cut-
offs (if used).
Follow local regulations with respect
to backflow preventers.
If oil-lubricated pumps are used,
ensure proper lubrication.
If motorized zone valves are used,
refer to maintenance instructions
provided with zone valves.