Initial Start-up, Inspection and Maintenance
58
Steps
(continued)
18. Check diaphragm expansion tank and system pressure
S
ervice
Start-up and Maintenance
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. 60 ºF/15.6 ºC.
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.
3.
Top up with water until filling
pressure is higher than the inlet
pressure of the diaphragm expansion
tank.
With the system cold, the filling
pressure must be approx. 3 psig
higher than the static pressure.
Max. operating pressure:
45 psig
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Min. operating pressure:
14 psig
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.
When starting up the system for the
first time, mark this value as the
minimum filling pressure on the
manometer.
A lower manometer reading usually
indicates loss of water due to
leakage. All leaks must be repaired.
19. Check functioning of safety valves
S
ervice
Start-up and Maintenance
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
manufacturer.
Refer to maintenance instructions
supplied with low water cut-offs,
pumps, etc.
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.
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