47
LEGEND
A
Gas
B
ICold water inlet
C
Hot water outlet
D
System delivery
E
System return
1
Air bleed valve
2
Control electrode
3
Nozzle connection
4
Ignition transformer
5
Ignition electrodes
6
System delivery control sensor
7
System return control sensor
8
Fan
9
Air pressure switch
10
Gas valve
11
Water trap for condensate discharge
12
Expansion tank
13
Circulating pump
14
Hot water sensor
15
3-way valve
16
Water-heater
17
Filling cock
18
Safety valve
19
Drain tap
20
Lack of water pressure switch
21
Air bleed tap
D C A B
E
1
2
3
5
4
8
9
7
6
1
13
11
10
19
18
16
15
14
12
20
21
17
HYDRAULIC CIRCUIT
