Installation instructions S-HR series page 20
10 Switching off the unit
In some situations it may be that the entire unit must be
switched off. By switching off the three keys with the
lamps for central heating, hot water and pump program,
the unit is switched off. STREBEL advise to leave the
plug in the wall socket, by which means the circulation
pump and the three-way valve are activated once every
24 hours in order to prevent jamming.
In the event of frost danger it is advisable to
drain the unit and/or the installation.
11 Commissioning and
maintenance
The top of the casing is hooked behind a locking edge
and is locked behind the door on the front of the casing
with a screw. After removing this screw the casing must
be lifted at the bottom by which means it is released from
the locking edge. Then the casing can be removed
forward.
With the S-HR settings such as burner pressure and
adjustment of the air quantity are unnecessary, due to
the fact that the unit operates with a so-called zero
pressure control. By this means the correct gas quantity
is controlled by the suction operation of the fan. The fine
adjustment which is carried out at the factory is once-
only, which means that adjusting of these values is
unnecessary.
11.1 Checking for contamination
In order to be able to check the unit for contamination in
the following running years it is advisable to measure
the maximum air displacement in the unit when putting
the unit into operation. This value can be different with
each type of unit.
In order to be able to measure this value the following
operations must be carried out:
- in order to enter the service chapter feed in the
access code as described on page 18;
- select the manual fan setting without burner action
Step
, by means of the Step key which will
indicate that the fan is off
;
- connect the digital pressure gauge hose to the
uppermost measuring nipple of the gas block
according to figure 12 (open it before fitting the
hose);
- take the fan to its maximum number of revolutions by
means of the + key;
- measure the pressure difference and write down this
value;
- when next servicing the unit the value of the fan
output may not have reduced by more that 20%
compared to the value during commissioning. If this
value is lower than 20% the unit does not require
maintenance.
11.2 Checking of the zero pressure control
The zero pressure control is set at the factory. This can
be checked by means of the following action;
- make sure that the unit is in operation and that it can
discharge the heat which it produces;
- in order to enter the service chapter feed in the
access code as described on page 18;
- select the manual fan adjustment with burner action
Step
by means of the Step key, which will
indicate that the manual operation is off
;
measuring point air pressure difference
figure 12
