Vaillant ecoTEC plus 937, Operating Manual

11

Operating instructions ecoTEC plus 937

If the storage tank charging function is switched off, the 
tank is not held at temperature. The unit only switches 
on in this case if the water is drawn off and only 
operates in the through-flow mode.

H

 Danger!

Danger of scalding!
The units are equipped with an automatic 
Legionella protection switching system:
If the temperature in the hot water tank falls 
below 50 °C, the tank is heated up to 70 °C 
once every 24 hours. In this case there is a 
danger of scalding when drawing the water off.

The Legionella protection system can be de-activated in 
the diagnosis level. For further information see installati-
on and maintenance manual, Section 6.1.4, Storage tank 
charging and Section 8.1.2, Diagnostic codes.

Activating the storage tank charging system

•  Switch on the appliance.
•  Turn the knob for setting the hot water temperature to 

the temperature you require.

bar

i

F

P

2

1

Fig. 4.9  Display during storage tank charging

•  Activate the storage tank charging by turning the knob 

for adjusting the hot water draw-off temperature all 
the way to the right-hand end stop.

The " " symbol is displayed.
•  Turn the knob for setting the hot water temperature to 

the temperature you require.

De-activating the storage tank charging

•  De-activate the storage tank charging by turning the 

knob for adjusting the hot water draw-off temperature 
all the way to the left-hand end stop.

The " " symbol disappears.
•  Then set the desired draw-off temperature. The unit 

then operates in the through-flow mode, the storage 
tank is not held at temperature. 

4.4.4  Drawing off the hot water

1

Fig. 4.10  Drawing off the hot water

When one of the hot water taps (

1

) at a draw-off point 

(wash-basin, shower, bath etc.) is opened, the unit 
automatically starts up and provides hot water.
When the hot water tap is switched off the unit switches 
off (or, if required, continues to operate for the heating 
system or to recharge the storage tank).

4.5 Heating 

operation

The boiler can only be used if the heating system has 
water in it (see Section 4.2.2).

4.5.1 

Setting the flow temperature

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P

1

2

Fig. 4.11   Setting the flow temperature

Set the flow temperature by using the knob (

1

).

We recommend the following settings:
– 

Left-hand setting

in Spring and Autumn,

– 

Mid-position setting

   in reasonably cold weather

– 

Right-hand setting

in very cold weather

Operation 4