Technical data

31Instructions for installation and servicing ecoMAX 31
4.17.5 Connection details for external time switches
and boiler terminal strip
Fig. 4.20 shows the connection details where a time
switch is used without a room thermostat to control the
boiler.
Important:
The arrowed numbers indicate connection into
the relevant terminal in the boiler terminal strip.
If a room thermostat is to be connected in addition to a
time switch the wire between the time switch ”ON” ter-
minal and boiler terminal 4 should be broken by the
contacts of the room thermostat (see schematic layout,
Fig. 4.21).
4.17.6 Vaillant optional plug in timer accessories
Refer to the instructions supplied with the optional
accessories for connection details. Upon completion of
all electrical connections refit the terminal box cover by
pushing into place. The cover is secured by two locking
clips.
4.18 Controls (ecoMAX 600)
4.18.1 External electrical controls
The boiler terminals 3, 4 and 5 are for connecting exter-
nal electrical controls such as a programmer, room ther-
mostat, etc. Terminals 3 and 4 are linked together when
the boiler is supplied. If external controls are used, this
link must be removed, and the controls connected
across terminals 3 and 4. Terminal 5 is an additional
neutral connection for external controls.
4.18.2 Connection of external electrical controls
4.18.3 Connection details using an external wiring
centre
The boiler should be connected to the system controls
using an external wiring centre. Fig. 4.22, 4.23 shows
connection details for a system utilising a 3 port mid
position motorised valve, figure 4.24, 4.25 shows the
connection details for a system utilising two 2 port
motorised valves (Important: the arrowed numbers indi-
cate connection into the relevant terminal of the exter-
nal wiring centre).
4.19 Thermostatic radiator valves
The boiler has a built in automatic bypass valve making
it ideal for use in systems with thermostatic radiator val-
ves (no separate system bypass is required). For opti-
mum fuel economy where TRV’s are used they must be
used in conjunction with a boiler control interlock. A pro-
grammable room thermostat or separate timer and
room thermostat will ensure complete boiler shut down
when the heating demand is satisfied. (The radiator in
the room containing the room thermostat should not be
fitted with a TRV).
4.20 Frost protection
The boiler has an integral frost thermostat which is desi-
gned for protection of the boiler. To protect remote or
exposed parts of the heating system or property additio-
nal frost protection measures must be taken such as the
installation of an external frost thermostat. This frost
thermostat should be connected across the boiler termi-
nals 3 and 4, in parallel with any external heating controls.
Note:
External frost protection cannot be used when
plug in timers are utilised.
4.21 Circulating pump
The boiler incorporates a built in circulating pump that is
fully prewired (no additional wiring is necessary). The
pump incorporates an automatic overrun period after
the boiler switches off.
4.22 Anti–cycling ‘economiser’ control
The boiler incorporates a built in anti–cycling control to
ensure that energy wasteful short cycling of the boiler
cannot occur. This control prevents the boiler from
re–igniting for a preset period after central heating ope-
ration (the hot water operation is unaffected by this con-
trol and hot water can be drawn at any time).
Note:
To temporarily override the anti–cycling control
turn the main boiler on/off switch to the off
position ”0” and then back to the on position
”I” after a few seconds.
4.23 Automatic pump spin control (APS)
The boiler incorporates a built in control which will spin
the built in circulating pump and operate the diverter
valve (ecoMAX 800) once in a 23 hour period. This con-
trol helps to prevent seizure when the boiler is not ope-
rated for a period of time. This control is not active
when the power supply to the appliance is turned off.
Boiler installation sequence 4
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