3
Fig 2:Typical twin controller current sensor installation.
11. Turn on the breaker and switch to the fused spur, the healthy
LED should flash/blink.
12. Turn down the Load Pot to the mid position and Time Pot to
minimum.
13. Turn on the breaker and the cooker/shower isolating switch.
14. Turn on the cooker/shower to low power and the current load
LED should light up. After approximately five seconds the run
LED should light up and the fan should run.
15. Adjust the load pot if necessary. Anti-clockwise to increase the
sensitivity and clockwise to decrease the sensitivity.
16. Now set the time pot by turning it clockwise. It has a range of
1 to 25 minutes for optimum performance and energy
conservation, a 20 minute overrun time is probably the best
starting point. N.B. the overrun time serves two functions:
the first to ensure the fan does not cycle with the cooker/
shower thermostat. Second to clear residual steam and
condensation following and after showering has finished.
17. Turn off the fused spur and fit the front cover plate to complete
the installation.
Temperature Sensing
18. Where used for temperature sensing to a normal shower, the
sensor must be fitted to the hot water dead leg. Find a position,
on the pipework which must be uninsulated copper. Remove
any paint or corrosion from the pipe, apply thermal grease to the
flat part of the sensor then firmly secure the sensor to the pipe
using the clip provided. It is most important that good thermal
conductivity is obtained. (see fig. 3 below).
19. From wherever the sensor is fitted, find a suitable route to run
the sensor control wiring to the main controller. At all times
ensure the wire does not get damaged by trapping of the cable.
20. Wire the cable into the terminals as indicated in the diagrams.
21. Test out all wiring, ensure that fan has a good earth by carrying
out a continuity test between the fused spur and the fan. Either
wire the fan for high speed operation or turn the fan on to high
speed and fix the setting.
22. Turn on the breaker and switch to the fused spur, the healthy
LED should flash/blink.
23. Turn down the load pot to the mid position and time pot to
minimum.
24. Turn on the shower wait 30 seconds after the hot water is being
delivered, if the load LED does not light up, then turn the load
pot very slightly in an anticlockwise direction, do not turn the pot
below the 50% position as this will allow the fan to run when
not required. If a lower setting is needed first check that the
temperature of the hot water is above 60oC as it should be to kill
off legionella, if it is at this temperature then the integrity of the
conduction of heat from the pipe to the sensor should be care
fully checked.
25. Now set the time pot by turning it clockwise. It has a range of
1 to 25 minutes for optimum performance and energy
conservation, a 20 minute overrun time is probably the best
starting point. N.B. the overrun time should be set to ensure
the fan clears all residual steam and condensation after
showering has finished.
26. Turn off the fused spur and fit the front cover plate to complete
the installation.
Installing a manual fan push switch (momentary)
e.g. MK - Reference: K4878P-WHI
27. Turn off the fused spur to the control unit and remove the front
cover.
28. Wire the cable into the terminals as indicated in the wiring
diagram figure 4 (i.e. OVERRIDE).
29. Run the cable to suitable location for the override switch and fix
securely.
30. Test the operation of the switch. Push and hold until the fan
starts running, this will give an override time of approximately
25 minutes. Push and hold the switch until the fan turns off, this
will disable the override during the 25 minute period.
31. Turn off the fused spur and fit the front cover to complete the
installation.
Special Notes regarding Temperature Sensing
a) There will be an inevitable delay between hot water being
delivered at point of use and the controller sensing the
temperature, this is due to the time taken by the conduction of
heat from the water through to the outside of the pipe and then
to the clamp on sensor. This time delay will vary with ambient
conditions, hot water temperature and pipe wall thickness. it is
most important therefore that great care is taken when fixing
the sensor to maximise the heat conduction process.
Please pay particular attention to cleaning the pipe, applying the
thermal grease and clamping the sensor.
b) Similarly there will be a delay in the unit turning off the fan as it
will take time for the dead leg to loose heat, again this will vary
with ambient conditions, hot water temperature and pipe wall
thickness.
The time of this natural cooling process should be taken account
of when setting the run on timer. As a guide, at an ambient
temperature of 21oC and a hot water temperature of 50oC. the
cooling down process will be 5 – 10 minutes and this should be
taken into account when setting the overrun timer.
c) The temperature sensor must be fitted to the copper pipe. With
plastic plumbing systems a section of copper tube must there-
fore be installed to receive the sensor.
