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When using forced circulation with the pump it is desirable to fit the boiler with the TH 163 thermostat located on
the outlet pipe from the boiler. This thermostat will switch the pump on as soon as the water temperature in the
boiler reaches 70 °C. The pump will be deactivated should the water temperature fall below 60 °C.
If the boiler is installed in the forced circulation heating system (with circulation pump), the boiler shall
be secured against pump failure or power outage for the pump motor respectively. This shall be carried
out in compliance with the Czech standard CSN 060830, Securing the central heating equipment.
I)
Installation and operating instructions for the pressure expansion
vessels
designed for the steel boilers of up to 50 kW according to CSN 07 0245
The pressure expansion vessels have been used increasingly in the level and central heating systems recently.
Their utilization brings a number of benefits, the most important of which is preventing the air ingress into the
system. Some pressure expansion vessel based systems experienced an excessive pressure buildup due to an
incorrect design. Another size calculation method for pressure expansion vessels for the steel boilers of up
to 50 kW to CSN 07 0245 with respect to the max. pressure difference which cannot damage the boiler body
during dynamic loading has been proposed based on the long-term testing of boiler bodies. This pressure
difference (B) has been determined to 50 kPa for the steel boilers.
The main principles that shall be met during installation of the pressure expansion vessels for the steel
boilers of up to 50 kW are given underneath. Should any of these principles not be met, warranty shall
not apply to the damaged boiler with the pressure expansion vessel.
1)
The supply pipe of the pressure expansion vessel shall be as short as possible without closures and it
should allow extension. The expansion vessel shall be positioned so that heating of the vessel by radiant
heat cannot occur.
2)
Each heating system shall be fitted with at least one safety valve positioned on the discharge pipe or on the
boiler and the pressure gauge. Location, installation and inside diameter of the safety valves shall meet
provisions of the Czech standards CSN 06 0830, ON 06 0830.
3)
Correct overpressure setting (200 kPa) of the safety valve shall be checked during installation. This is the
pressure, the safety valve shall open at. Please readjust the safety valve if it is set incorrectly.
4)
Installation and setting of the safety valve, check and adjustment of the gas pressure in the pressure
expansion vessel shall be performed by qualified organization only. The gas pressure in the expansion
vessel shall be measured prior to priming the system with water. Check whether it is higher than the
hydrostatic height in the system.
5)
The heat source shall be fitted, among others, with the flue controlled in compliance with the Czech
standard CSN 06 0830. This applies to solid fuel boilers of up to 50 kW output. The higher admissible
operating temperature is limited to 95 °C.
6)
The pressure expansion vessel as well as the supply pipe shall be protected against water freezing.
7)
The gas filling overpressure in the expansion vessel shall be adjusted by releasing to the hydrostatic
pressure of the system in cold condition. This shall be performed using the tire valve installed on the
pressure expansion vessel. The overpressure should be measured by the pressure gauge which is normally
used for checking the tire pressure. Adjust the pressure by adding water to the system to the value which is
max. 10 kPa higher than the hydrostatic height in the system.
8)
After priming the system with water, mark the adjusted hydrostatic height and max. pressure in the system
after reaching the water temperature of 90 °C. Mark these values by lines on the pressure gauge.
9)
If the pressure difference changes during operation (i.e. minimum or maximum pressure is exceeded), the
system shall be checked, bled, water shall be refilled in cold condition and/or increase the gas pressure in
the pressure expansion vessel as per manufacturer's instructions.
10) The maximum hydrostatic height for boilers according to CSN 07 0245 when using the pressure expansion
vessel may reach 12 meters.
Hot Water Boiler Manual – Models H 635, H 650
9
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