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The following scheme below shows the behavior of the 3-way valve and boiler circulator during one whole cycle
of De-Air sequence with a DAir_Repetition_OnOff set to 2.
ON
Boiler Circulator
OFF
Figure 7. 8
Relevant variables:
Specific Parameters
De_Air_Config
0 = DAir disabled; 1 = DAir enabled.
De_Air_State
Current state of the DAir function.
DAir_Repeation_OnOff
Number of repeating ON/OFF.
DAir_Number_Cycles
Number of DAir cycles.
Table 7. 6
Automatic Feed Valve
If an automatic feed valve is installed in the system, it may not be left open indefinitely. A continuous feed of fresh
water could damage the system (fresh water is bringing fresh oxygen into the system). It is recommended that
after a short period of time following the installation of the boiler into a heating system that the automatic feed
valve be closed
When using an automatic water refill system some precautions must be taken, like installing a water meter to
measure and evaluate the total water volume that is added to the system. A water meter can be used to detect
and eliminate any water leakage as soon as possible.
When an automatic feed valve system is used, some form of logging must take place to prevent continuously filling
of the system with large amounts of oxygenated fresh water. This can happen when a leak in the system is not
detected and the total added water amount is not being logged.
Water pressure
The installation must be designed and built to conform to all applicable regulations and standards, including the
right safety relief valves. IMPORTANT: Always keep the pressure in the boiler lower than the value at which its
safety relief valve opens.
Sensor
A water pressure sensor has been built into the boiler. The minimum water pressure in the boiler is 15 psi and the
maximum pressure is 87 psi. The normal water pressure must be between 22 and 50 psi. Or 22 and 75 psi when
the optional pressure relief valve is used. The pressure sensor will stop the boiler from firing when the water
pressure drops below 10 psi, and starts the boiler firing again when the water pressure reaches above 15 psi.
These values may never be changed in the boiler control settings. The boiler cannot be properly purged of air if
the water pressure is less than 15 psi.
Higher pressure systems (e.g. in high buildings)
If a pressure higher than 87 psi is required for the heating system, the best solution is to separate the system from
the boiler by means of a plate heat exchanger. In this way, the boiler pressure can remain under 87 psi. (60 psi
recommended)
Level
(Default) Value
2: Installer
0
1: User
-
2: Installer
2
2: Installer
10
E93.1601EN032.C VGH installation manual
t
Range
0...1
-
0...255
0...255
27
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