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Annex II
Guidance to select an expansion membrane tank
Selecting an expansion membrane tank in case of using water as a heat carrier
In case of connecting the boiler to the heating system with a volume of more than 70 liters, it is necessary to install an additional expansion membrane tank,
connecting it to the return heating line really close to the boiler.
In the tables presented below, you can find water volume necessary for filling the elements of the heating system. The volume of the boiler by itself is 2 liters.
This data allows to make an approximate calculation of the water quantity in the heating system to which the boiler will be connected.
TABLES FOR WATER VOLUME CALCULATION:
Another way to determine water volume in the heating system is to compare values of the water sensor
before and after filling the system 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 meter. Initial pressure in the expansion tank should be approximately 10% more
than calculated static pressure.
Example:
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 up,
calculated pressure is considered as initial one in the heating system with cold water.
.
Copper pipes
Pipes
diameter, mm
Water
quantity, l/m
p.
10х0,8
0,05
12х1,0
0,08
15х 1,0
0,13
18х 1,0
0,20
22х1,2
0,30
28х1,2
0,52
35х1,5
0,80
42х1,2
1,20
Steel pipes
Pipe
diameter, mm
Water quantity, l/m
p.
G3/8
0,13
G1/2
0,21
G3/4
0,38
G1
0,60
G11/4
1,02
G11/2
1,39
G2
2,21
G21/2
3,72
G3
5,13
G4
8,71
Water volume in the radiators
Radiator type
Power,Wt
Volume, l
Cast-iron:
For 1 gill
500/160
130
1,01
ТА-1
150
1,34
Т-1
125
1,18
Steеl:
For a radiator
11-400/960
915
2,78
11-600/960
1282
4,15
22-600/960
2225
8,30
11-600/1000
1310
2,97
22-600/1000
2225
5,93
11-600/900
1179
3,10
22-600/900
1984
6,30
11-590/960
1091
3,20
22-590/960
1908
6,50
The power is indicated for the parameters 90/70/20 °С,
where: 90 –temperature in the direct heating line;
70 – temperature in the reverse heating line;
20 – temperature in the premise