Alpha E-Tec Plus 28NX - Page 10

3.8 BOILER SCHEMATIC
1 Cold mains isolation valve with
integrated filling valve
2 Gas isolation valve
3 Air vent drain valve (do not block)
4 Gas valve
5 DHW flow switch
6 Gas injector
7 Flow regulator
8 DHW temperature sensor
9 Condensate trap
10 3 bar safety valve
11 Expansion vessel
12 Venturi positive pressure point (+)
Fig. 3.4
13 Pressure signal vent fitting
14 Venturi
15 Primary flow temperature sensor
16 Burner
17 Flue temperature sensor
18 Air supply pipe
19 Flue test point (pressure point +)
20 Air test point (pressure point -)
21 Primary heat exchanger
22 Ignition/sensing electrode
23 Primary return sensor
24 Fan
25 Automatic air vent
26 Boiler pump
27 Primary pressure sensor
28 DHW heat exchanger
29 Diverter valve
30 By-pass
31 Drain point
32 Safety valve indicator
33 Filling loop
34 Heating return isolation valve
with integrated filling valve
35 Heating flow isolation valve
Alpha E-Tec Plus 28NX, 33NX and 38NX - Technical Data
Gas
Condensate discharge
and expansion relief
Primary
Heating
return
Primary
Heating flow
Domestic
hot water
outlet
Cold mains
water inlet
3
4
5
6
7
8
27
10
11
12
13
14
15
17
18
16
19
21
22
23
24
25
26
28
29
30
9
31
34
35
33
32
2
1
20
10