Preparing the heating hydraulic system - secondary
Prepare the system according to one of the recommended hydraulic schemes (
Catalogue of Hydraulic
Wiring Diagrams
) which is specified by the manufacturer of the device. This is the only way to ensure
reliable and effective operation of the device. After connecting the device to the heating system, it is
necessary to examine all circulating pumps and electric motor valves if they function correctly.
The device must be connected to the heating system via rubber compensator or flexible pipes. The
latter must not be under tension in final position, this would worsen the devices noise and vibration
protection. In extreme cases this can also lead to damage to the device.
Quality of heating water
Maximal allowed content of individual substances in the heating water and the influence of these on the
heat exchanger are presented in the table below. It is not allowed to use heating water which contains
any substance in concentrations which cause corrosion in the heating system (influence “-”). It is also
not allowed to use heating water which contains two or more substances in concentrations which could
cause corrosion in the heating system (influence “0”).
TYPE OF PRESENT
SUBSTANCE
UNIT
CONCENTRATION
INFLUENCE TO THE HEAT
CONDUCTOR
Organic sediment
mg / L
0
Ammonia NH
3
mg / L
< 2
1 to 20
> 20
+
0
-
Chloride
mg / L
< 300
> 300
+
0
Allowed water hardness
°dH
5 – 10
Electrical conductivity
µS / cm
< 10
10 to 500
> 500
0
+
-
Iron (Fe) removed
mg / L
< 0.2
> 0.2
+
0
Free carbonic acid
mg / L
< 5
5 to 20
> 20
+
0
-
Manganese (Mn) removed
mg / L
< 0.1
> 0.1
+
0
Nitrates (NO
3
) removed
mg / L
< 100
> 100
+
0
pH value
mg / L
< 7.5
7.5 to 9
> 9
0
+
0
Oxygen
mg / L
< 2
> 2
+
0
Hydrogen sulphide (H
2
S)
mg / L
< 0.05
> 0.05
+
-
HCO
3
- / SO
4
2
-
mg / L
> 1
< 1
+
0
Hydrogen carbonate
mg / L
< 70
70 to 300
> 300
0
+
0
Aluminium (Al) removed
mg / L
< 0.2
> 0.2
+
0
Sulphates
mg / L
< 70
70 to 300
> 300
+
0
-
Sulphite (SO
3
)
mg / L
< 1
+
Chlorine (gas) (Cl
2
)
mg / L
< 1
1 to 5
> 5
+
0
-
Table: Influence of various aggressive substances in the heating water on the stability of stainless
copper welded plate transmitters. (+ = no influence,
0
= danger of corrosion,
-
= corrosion - use not
permitted).
