Installation & Servicing instructions
AT
AG XL
34
8.1 External controls
NOTE:
- T10 common flow sensor (supplied) must be connected
- T4 outside sensor (optional) is adviced to be connected.
The ATAG XL provides many possibilities to operate the boilers from external controls.
Only 1 type of control can be connected. Connections of the external control
must be done in the master boiler (address 01) on terminal 3 and appropriate
connections.
Below you will find a description of the possibilities and parameter adjustments to take
account of.
1. On-Off contact
An On-Off contact is a volt-free switch to create a heat demand with closed contact.
The On-Off control must be connected to terminal 3, position 7 and 8. This is also the
connection for an OpenTherm-control, but it is self-detecting. No specific adjustments
are necessary. See chapter 9.4 to adjust the flow temperature.
2. OpenTherm-control
An OpenTherm-control is a digital controller which is communicating with the boiler ac-
cording the OpenTherm-protocol. The controller calculates continuously the desired flow
water temperature and sends this to the boiler(s).
ATAG supplies the MadZ zone controller (AG1MZ05U).
The OpenTherm-control must be connected to terminal 3, position 7 and 8. This is also
the connection for an On-Off contact, but it is self-detecting. .
After connecting an OpenTherm-control P230 will be visible (Setting level, Param. Chap-
ter, Cascade Param.) where the maximum set point CH can be adjusted.
For control option 1 and 2 counts that the boiler controls its own output (modulating) to
achieve the desired temperature. When this is achieved the boiler modulates back to
maintain the desired temperature and prevents over shoot.
If an OpenTherm controller of another brand than ATAG is used, it must be
ensured that for certain error messages the heat demand is not omitted. This
can result in complete loss of heat production.
0-10Volt
Open-
Therm
On/Off
T3
DHW
1 2 3 4 5 6 7 8 9 10 11 12 13 14
T10
General
purpose
LWCO
T4
Out
Figure 8.1.a
0-10Volt
Open-
Therm
On/Off
T3
DHW
1 2 3 4 5 6 7 8 9 10 11 12 13 14
T10
General
purpose
LWCO
T4
Out
Figure 8.1.b
OpenTherm error messages
The coding of the transmitted Error Messages on a OpenTherm controller is displayed as follows:
(E) EB (E = Error Code = B and boiler number)
example: Error Code Ex02SC02 on boiler 6 will appear as (0) 26
