Technical information
Installation of Boiler Controls 
Vitotronic 100, GC1 and Vitotronic 300, GW2 on Vitocrossal CT3 boilers (CT3-17 to CT3-89 models) 
Refer to boiler manual for more detailed instructions on the boiler jacket assembly 
2 
3 
4 
IMPORTANT 
Route and insert fixed high limit, 
adjustable high limit capillaries as 
well as boiler temperature sensor 
to rear of boiler before installing 
boiler jacket and/or cover 
Install limit capillaries into correct 
wells and ensure pushed in all the 
way. 
WARNING 
! 
Ensure limit capillaries are not kinked 
or bent. This will adversely effect the 
operation of the limit. 
1  Side panel on Vitocrossal CT3 
boiler is designed for mounting 
control harness without the 
need for drilling holes. 
2  Control harness is fastened to 
the side of the boiler using the 
four supplied screws. 
3  Burner harness is installed onto 
the control harness. Position 
behind DIN rail and fasten 
screws at either end to secure. 
4  Control is installed on two tabs 
at the top of the control 
harness (mounting plate). 
Control pivots down into the 
burner harness housing. 
Control fastened down to 
burner harness housing with 
two screws. 
Control limit capillaries fed 
though rectangular access holes 
in boiler jacket. 
Insert limits into multi-point 
sensor well at back of boiler. 
Installation Steps 
Section 2 
Section 2.3 
1 
12 
5346540 v1.0 09/2006 Technical information subject to change without notice 










