BaltGaz NEVALUX 7224 User Manual page 45

Another way to determine water volume in the heating system is to compare values of the water sensor before and
after filling with water.
Minimal initial pressure in the expansion tank should not be less than the static pressure at the connection point of
the vessel.
Static pressure- is a pressure of the water column between the expansion vessel and the highest point of the
heating system. Measuring this height in meters, we calculate static pressure taking 0, 001 MPa of overpressure for
each height of meter. Initial pressure in the expansion tank should be approximately 10% more than calculated static
pressure/
For instance: Measured height is 8 meters, which corresponds to the value of the static value 0,08 MPа. Initial
pressure in the expansion vessel should be approximately (8х0,01) х 1,1=0,09 MPа. To sum I up, calculated pressure
is considered as initial one in the heating system with cold water.
Membrane expansion vessels have nipple apertures which serve for regulating and monitoring of pressure's
values in the gas part of the vessel. After you define the initial pressure, it is necessary to measure pressure in the gas
part of the vessel (for instance; by the car gauge) and then release or add (for instance; by the car gauge) the air up to
the set pressure value. Simultaneously you should consider that for the boilers BaltGaz NEVALUX the initial
pressure in the expansion tank should be at least 0,1 MPа and not more than 0,3 MPа.
Lower pressure can cause the boiler's operating failure.
To calculate the full volume of the expansion vessel you can use the following formula:
Vc =1,099*Vi*Av*(Рmах +0,1) / (Рmах – Р),
where:
Vi – full volume of heating system dm
Av – growth of water volume in the heating system from the heating up to the maximal possible temperature;
Рmах=0,3 MPа – maximal calculated pressure in the expansion tank (equals to the pressure of the safety relief
valve);
Р – initial pressure in the expansion tank начальное давление в расширительном баке (calculated according the
mentioned above method).
Expansion tank full capacity, [dm
In case, volume of the tank is between tyschemeal values, when choose, follow by the rule "first is larger".
In the boiler is installed a vessel with a volume 6 dm
If after calculating it will turn out that for such heating system it is necessary to have an extension tank of bigger
volume, it is necessary to install an additional extension tank, where its value will be equal to the difference between
calculated value and volume of the boiler's extension tank (6 dm
For instance: according to the calculation, the heating system requires to install an expansion tank with a volume 6
3 , i.е. 13 – 6 = 7 dm 3
dm
monograph you should choose the next bigger standard expansion tank with a volume 8 dm
3
;
Central heating system capacity, [dm
3
]
. Consequently, it is necessary to install additionally a vessel with a volume 7 dm
3
]
Starting pressure in the expansion tank
3
.
3
).
User's manual
3
. On the
3
.