Part 7 - Central heating (CH) and Domestic Hot Water (DHW) circuit
Connect an external expansion tank
The boiler comes standard with a 11 liter (2,9 US Gallon) internal expansion tank. In case the total size of the
installation configuration requires this, an extra expansion tank needs to be selected with regard to the total
installation size and static pressure. Install the external expansion tank in the CH return pipe (figure 7.6).
Make sure there is always an open line in the CH system and expansion tank.
Installation volume using
internal expansion vessel
If the installation operates at 194/158 F (90/70
°C) and 29 PSI (2 Bar) installation pressure
the volume of the installation is maximized to
17 Gallon (63 liters)
If the installation operates at 194/158 F (90/70
°C) and 22 PSI (1,5 Bar) installation pressure
the volume of the installation is maximized to
30 Gallon (115 liters)
If the installation operates at 176/140 F (80/60
°C) and 22 PSI (1,5 Bar) installation pressure
the volume of the installation is maximized to
40 Gallon (150 liters)
Cxxx types: CH return
Figure 7.6 Expansion vessel to be located in
Hxxx
thereturn
types:
pipe
CHreturn and Tank return
Figure 7.6 External expansion tank to be located in the CH return pipe
Use of pumps and maximum remaining pump head of internal pump at CH supply connection
The boiler is equipped with an internal pump. This pump is to be used as the only pump in the installation or as
the only pump in the primary circuit.
Warning
Installing a pump in series with the internal pump is not permitted. It will cause unwanted effects on the
boiler control. This might result in noise or delta T irregularities.
In the graph below the maximum remaining head at the boilers CH supply is depicted. Installations with a
higher internal resistance should be supplied via low loss headers and zone pumps (see examples).
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