Pressure Relief Valve; Pressure Gauge; Heating Circuit Expansion Vessel; Shift Load Storage Tank Expansion Vessel - Vaillant ecoTEC plus 937 Instructions And Maintenance Instructions

3 General requirements

3.10.3 Pressure relief valve

The boiler is equipped with a pressure relief valve. This
safety device is required for all sealed central heating
systems, is preset to 3 bar and is fitted with a 15 mm
compression connection for the discharge pipe, whose
diameter must not be less than 15 mm. The pressure
relief valve must not be used for draining purposes.

3.10.4 Pressure gauge

The pressure gauge is fitted to the boiler in the factory
and indicates the pressure of the primary circuit, to
make filling and testing easier.

3.10.5 Heating circuit expansion vessel

The boiler of the ecoTEC series are equipped with a 10 litre
expansion vessel which is suitable for a sealed heating
system with a maximum water volume of 100 litres.
If the nominal capacity of the boiler expansion vessel is
not adequate for the heating system (e.g. when modern-
ising old open systems) an additional expansion vessel
can be fitted outside the boiler. The pressure gauge
must be fitted in the return pipe, in accordance with
BS 5449: Part 1, as close as possible to the boiler.
In Table 3.5 you will find an overview of the required
size of an additional expansion vessel.
Initial system pressure (in bar)
Setting of the excess pressure valve (in bar)
Total water volume of the system (in l)
25
50
100
125
150
175
200
225
250
275
300
325
350
375
400
425
450
475
500
With other system volumes than shown above,
multiply the volume by the adjacent factors
Table 3.3 Size of an additional expansion vessel
16

3.10.6 Shift load storage tank expansion vessel

The shift load storage tank is fitted with a 1 litre expan-
sion vessel.
3.11
3.11.1
The circulation pump is integrated in the combi boiler.
The remaining head of the pump with respect to the
bypass valve is shown in Fig. 3.8.
The operating mode of the 2-speed pump can be adjust-
ed using diagnostic number d.19, see Section 8.1.2.
400
300
200
100
0
Fig. 3.8 Technical data of the pump in the combi boiler
Vessel volume

3.11.2 Shift load storage tank circulation pump

(in l)
The shift load storage tank is equipped with a mainte-
1.0 1.5 nance-free charging pump.
3.0
3.12
The boiler is fitted with an automatic system by-pass.
2.7 3.9
The installation can be used in systems with thermostat-
5.4 7.8
ic radiator valves without the need for an additional
by-pass. The by-pass valve is adjustable, see Section 5.8.
10.9 15.6
13.6 19.5
3.13
16.3 23.4
The boiler is fitted with an automatic air vent. Other
19.1 27.3
measures need to be taken to allow the heating system
to be either automatically or manually vented during
21.8 31.2
filling and during commissioning.
24.5 35.1
27.2 39.0
3.14
30.0 42.9
The boiler is fitted with a siphonic condensate trap
incorpaorating a water seal of 145 mm.
32.7 46.8
35.7 50.7
38.1 54.6
40.9 58.5
43.6 62.4
46.3 66.3
49.0 70.2
51.8 74.1
54.5 78.0
0.109 0.156
Installation and maintenance instructions ecoTEC plus 0020031552_03

Details for the pumps

Circulation pump

1. Step
0 200 400 600 800 1000 1200

System-Bypass

Venting

Condensate siphonic trap

2. Step
1400 1600 1800 2000
Volumeflow [ l/h ]