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Hot Water Boiler with Steel Body, Automatic Fuel Feed Operation and Maintenance Manual
Example: The volume of open expansion tank required for a 60,000 kcal / h boiler is 90 liters.
Open expansion tanks were selected by considering the open expansion volumes of Ünmak brand and panel
radiator in the system.
Wiring diagram with open expansion tank
Warning of corrosion in installation:
ÜNMAK boilers are extremely resistant to corrosion and therefore corrosion. However, all iron-based
components in the heating installation (including installation pipes and radiators) must be protected
against corrosion. Oxygen in the heating water causes oxidation of the iron surfaces resulting in rust
and thus loss of material.
During the initial filling of the installation, the accumulated air must be evacuated. Usually, if the
necessary measures are taken after the first filling, there is no damage caused by the oxygen in the
water. Oxidation is mostly caused by oxygen which is involved in the heating water during operation.
The main reasons are:
1. In systems with open expansion tank, oxygen is added to the system because the tank is open
to the atmosphere. For this reason, the information given in this manual must be strictly
observed in the open expansion tank dimensions, the position in the system and the safety
connections.
2. Leaks in the system cause oxygen to be added to the heating water. Therefore, the lowest
water pressure in the closed expansion tank system must be higher than the atmospheric
pressure and periodic control of the operating pressure is required.
