Sime Murelle 25 BF Installer'S Instructions Download Page 42

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– Reduce the D.H.W. draw off rate to the minimum neces-

sary to maintain the burner alight by carefully adjusting
the D.H.W. inlet valve and check that the burner pressure
decreases in response to D.H.W. temperature rise. Fully
open the inlet valve.

– Close the D.H.W. tap and ensure that the burner is extin-

guished and the pump stops.

4.3

SETTING THE C.H. INPUT

– Turn the rotary switch to the WINTER position “

❄

" and

ensure that the room thermostat (if fitted) is calling for
heat. Turn the C.H. thermostat knob to maximum (fully
clockwise) and the burner will light.

– Allow the boiler to run for at least 5 minutes and check

the burner pressure. The heating input is factory set as
stated in

Table 3.

– If the heating output is to be adjusted, proceed as follows:

– refer to section 1.3 and establish the desired burner

pressure;

– remove (pull forwards) the C.H. knob protecting the

potentiometer;

– set the burner pressure as required using a small

screwdriver on potentiometer (1 fig. 19). Rotate the
screw anti-clockwise to reduce the burner pressure;

– operate the rotary switch between SUMMER and WIN-

TER position a few times and check that the correct
burner pressure is maintained.

– Replace the C.H. knob over potentiometer.
– To set the time clock proceed as follows:
– push in the setting tabs around the clock dial at the

times corresponding to when the heating is desired ON;

– set the clock to the correct time by rotating the dial clock-

wise until the arrow corresponds to the current time.

4.4

SETTING THE D.H.W. FLOWRATE

A restrictor nut is fitted into the diverting valve to reduce the
D.H.W. flow to that which will give an acceptable D.H.W. tem-

perature. To set the D.H.W. flow, procede as follows:
– select Summer position “

” and turn the D.H.W. thermo-

stat to max.;

– fully open the D.H.W. tap furthest from the boiler;
– check that the boiler is firing at maximum burner pressure;
– adjust the D.H.W. flowrate by turning the restrictor lever

on the divertor valve until a D.H.W. temperature rise of
appr ox 35° C is achieved. This corr esponds t o t he
flowrates shown in

Table 4;

– turn off the tap;
– remove the pressure gauge and refit the sealing screw;

Remember that the flow rates and corresponding tempera-
tures of use of hot water, given in

Table 4, have been obtained

by positioning the selector of the circulation pump on the max-
imum value.

Should there be any reduction in the D.H.W. flow rate, the
filter installed on the inlet to the pressure switch valve will
need cleaning.
To gain access to the filter, first close the cold water isola-
tion valve (20, figure 2), drain the D.H.W. circuit via the low-
est tap, make provision to collect a small discharge of
water, then loosen the brass swivel connection to access
the filter.

4.5

FINAL CHECKS

– Re-light and test for gas soundness.
– Re-fit the casing front panel and securing brackets.
– Set the C.H. and D.H.W. potentiometers to the required

settings.

– Ensure that the time clock is set at the desired time peri-

ods. Set the room thermostat (if fitted) to the required
setting.

4.6

USER’S INSTRUCTIONS

Upon completion of commissioning and testing the system,
the installer should:
– Give the “Users Instructions” to the householder and

emphasise their responsibilities under the “Gas Safety
(Installation and Use) Regulations 1996 (as amended)”.

– Explain and demonstrate the lighting and shutdown proce-

dures.

– Advise the householder on the efficient use of the system,

including the use and adjustment of all system controls
for both D.H.W. and C.H.

– Advise the user of the precautions necessary to prevent