Vaillant ecoTEC plus 937, Instructions And Maintenance Instructions, Page: 33 / 64

33 Installation and maintenance instructions ecoTEC plus 0020031552_03
• Check that both stop valves on the combi boiler are
open.
• Connect the filling loop as described in Section 5.4.2.
• Open the water stop valve.
• Slowly open the isolator valve in the filling loop so
that water can flow into the heating system. Bleed the
radiator at the lowest point until water flows out of
the bleed valve without bubbles.
• Bleed all other radiators until the heating system is
completely filled with water, all bleed valves have
been shut and the manometer pointer is in the centre
of the dark grey area. Bleed the heating pump by loos-
ening the central screw. Close the filling loop valve
and the cold water stop valve.
• Loosen the cap on the automatic air vent by a couple
of turns. (In continuous mode the unit is vented inde-
pendently by the automatic air vent system.)
• Check all connections and the entire system for leaks.
5.5 Initial flushing of the system ("cold“)
h
Note
The entire heating system must be flushed
through completely at least twice: once cold
and once hot, in accordance with the following
instructions.
• Check if all radiator thermostat valves and both stop
valves on the combi boiler are open.
• Connect a hose to the drain valve which is located at
the lowest position in the heating system.
• Open the 1/2“ drain valves and all the bleed valves on
the radiators so that the water flows quickly and com-
pletely out of the heating system and the combi boil-
er, in order to remove the contamination caused dur-
ing the installation out of the heating system before
the combi boiler is started up.
• Close the 1/2” drain valves and radiator bleed vavles.
• Re-fill the heating system with water as described in
Section 5.4.3.
• Check that the pressure relief valve in the heating
system is functioning correctly by turning the handle
on the valve.
• Check the pressure in the heating system and top up
with water if necessary.
• Close the filling loop valve and the cold water stop
valve.
5.6 Filling the condensate siphon
d
Danger!
If the condensate siphon is empty during opera-
tion of the combi boiler there is a danger that
exhaust gases can flow into the room and
cause poisoning. For this reason you must
make sure that the siphon is filled up every
time the unit is cleaned.
• Remove the lower section ( 1 ) of the condensate
siphon by turning the bayonet connection in a coun-
terclockwise direction a quarter of a turn.
• Fill the lower section with water until about 10 mm
below the upper edge.
• Replace the lower section of the condensate siphon.
1
Fig. 5.4 Filling the condensate siphon
5.7 Setting the pump output
Only in ecoTEC plus appliances:
The output of the two-speed pump can be matched to
the requirements of the heating system. If required,
change the pump output, depending upon the setting of
the operating mode, under diagnostic number "d.19“
(see Section 8.1.2).
5.8 Adjusting the bypass
The appliance is equipped with an adjustable bypass
valve. The pressure can be set between 170 and
350 mbar. The valve is pre-set to approx. 250 mbar
(mid-position). Each turn of the setting screw changes the
pressure by approx. 10 mbar. The pressure is increased by
turning to the right and reduced by turning to the left.
1
Fig. 5.5 Setting the bypass valve
• Setting the by-pass valve using the setting screw (1).
Commissioning, Part I 5