27
Expansion vessel
Before fi lling up the heating system, check
pressure in the expansion vessel. The ini-
tial pressure inside the expansion vessel
should be by 0.2 bar higher than the assu-
med pressure in the heating system.
If the heating system is already fi lled up,
it is necessary to shut the heating water
valves located underneath the boiler and,
using the draining valve, relieve the boiler
from pressure. Then you can check the ex-
pansion vessel pressure and if necessary
increase the pressure.
Important:
Make sure that the expansion
vessel capacity is suffi cient for the volume
of water in the heating system (see instal-
lation design documentation).
Safety valve
At the bottom of the boiler among the hyd-
raulic group is on the right side located a
safety valve (Fig. 15). When the maximum
pressure in the system is exceeded, water
or steam can be discharged from the safety
valve, therefore we recommend to attach
a hose to the safety valve, discharging
the water into the building’s water waste
system.
Important: Under no circumstances may
anyone manipulate with the safety valve
while the boiler is in operation.
Connecting gas supply
The ZP (natural gas) version of the
PROTHERM 24 KTV, 28 KTV and 24 KOV
boilers is designed to be fuelled by natural
gas of nominal pressure in the gas mains
2 kPa, for which the calorifi c value is most
commonly stated as being between 9 and
10 kWh/m
3
. The indoor gas distribution
pipes and the gas meter must be sized
adequately, taking into account also the
user’s other gas appliances.
All gas distribution pipes must be installed
in accordance with ČSN EN 1775.
If your boiler is fuelled by propane gas
and the gas supply piping is installed
below the terrain level, the space around
the connection point must be suffi ciently
ventilated or equipped with a valve which
shuts off the section below the terrain le-
vel when the boiler fl ame is off. The valve
must also shut when the ventilation fails, i.e.
when the forced ventilation system fails or
when natural ventilation is monitored by a
detector (when the detector sends a war-
ning signal).
Important: The boiler’s gas connection point
is a ¾” gas valve coupling with a technolo-
gical fl attening. This technological fl attening
prevents the thread from being sealed in
a conventional way by a pipe union and
sealers such as for instance “combing”,
Tefl on, paste, etc. The coupling must be
sealed by merely tightening the cap nut
on the coupling end over an appropriate
24×15×2 fl at sealing ring.
After completing the gas supply connection
to the boiler, the coupling must be checked
for potential leaks.
Toping up boiler water
Toping up water in the boiler is described in
the part “Operating instructions – Service/
Maintenance” on page 13.
Fig. 15
Safety valve
