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7. Repair work
7.1. General
The following repair work may be done on this machine:
•
Setting the air pressure
•
Setting the pressure switch
In general, the following should always be heeded when
doing this work:
•
Screw locking devices such as spring washers must
always be exchanged.
•
Torque values must be complied with.
The following applies in general to repair work:
Switch the machine off, disconnect it from the grid,
clean it and lay it in a horizontal position on a firm
supporting surface. Secure it against falling over
and/or slipping!
Unless stated otherwise, the torque values in the Tables
should be used. Values for clean, lubricated screws. Tight-
ening torque [Nm] for A2/A4 screws (friction coefficient
= 0.2)
A2/A4,
strength class 70
DIN912/DIN933
M4
2.5 Nm
M5
3.5 Nm
M6
6 Nm
M8
16 Nm
M10
32 Nm
7.2. Setting the air pressure
The pressure vessel (E) contains an elastic membrane
(F). This membrane is compressed by an air cushion
with an air pressure of 1.5 bar. If the automatic domestic
water system has already been put into operation for the
withdrawal of small quantities of water, the air pressure
will have fallen. In this event, and every six months at the
latest, check the air pressure as follows:
•
First disconnect the plant from the grid (withdraw the
mains plug)
26 | EngliSH
A2/A4,
strength class 80
DIN912/DIN933
3.3 Nm
4.7 Nm
8 Nm
22 Nm
43 Nm
•
Then let the water located in the pressure vessel flow
away
•
Remove the valve cover (G) from the pressure vessel
and, using an air pump on the air valve (H), restore
the required positive pressure of 1.5 bar.
7.3. Setting the pressure switch
The pressure switch has standard settings for the switch-
on pressure (1.5 bar) and switch-off pressure (3.0 bar)
and, for normal operation of the plant, these need not
be changed. During the operation of garden sprinklers,
however, a back pressure high enough to reach switch-
off pressure may build up in the system, even though the
pressure pipe is not closed.
In order to prevent the pump switching off and on for
this reason, switch-off pressure can be increased at the
switch. In this and other cases when it is necessary to
change the switching value, you can do so directly at the
pressure switch.
To do this, disconnect the plant from the grid (withdraw
the mains plug). Unscrew the cover of the pressure
switch. Underneath it, there is a small tension spring and
a large tension spring (see Figure below). Tighten the
nut on the small spring to increase switch-off pressure,
and loosen the nut to reduce it. Tightening or loosening
the nut on the large spring increases or reduces both
switch-on and switch-off pressure simultaneously.
Check with a trial run that the desired switch-on and/or
switch-off pressure has been set. On no account should
the switch-off pressure be set so high that the pump out-
put cannot reach it, or the pump will continue to run with-
out delivering even if the pressure pipe is closed. This will
cause overheating and the destruction of the pump.
Switching-on and switching-off points for domestic
water systems:
HWE 55
On
1.5bar
Off
3.0bar
All others
1.5bar
3.5bar
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