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1. Water is heated instantaneously as it flows over the
heating elements in the copper cylinder (diagram 2).
2. The heaters are only switched on when sufficient
water is flowing.
This is done automatically with a switch which works
on water pressure and is indicated by the “High” or
“Medium” light illuminating, depending on whether
Button “A” or “B” has been pressed.
3. The water is turned on and off by the solenoid valve
built into the shower. This is switched on by
pressing Button “A”, “B” or “C”.
4. The flow of water is automatically held at the level
set by the user even though the supply pressure
may vary (see “Effect of Other Water Devices on
Incoming Water Supply”).
5. If the water supply falls below a set limit, the
pressure switch will operate and switch off the
power to the elements. This is indicated by the “Low Pressure” light illuminating (see “Effect of
Other Water Devices on Incoming Water Supply”).
6. As a further safeguard, a thermal cut-out switches the power off if the water temperature
climbs above the set limit and the “Overheat” light will illuminate.
This cut-out, which gives an audible click, may also operate due to residual heat when the shower
is switched off. It will reset itself if water is run through the shower for 10 to 20 seconds, and
the “Overheat” light will go out.
7. The pressure relief device is to safeguard against abnormal pressure conditions.
Effect of Seasonal Incoming Water Temperature Changes
The required water temperature is achieved by adjusting the rate of water flow.
Diagram 3 shows the principle involved in relating temperature rise to flow rate.
The higher the water rate the lower the temperature and vice versa.
The temperature of the water supplied from the mains can vary considerably
throughout the year from 5 to 20°C.
This means that in the winter, flow rate will be less than in the summer to
achieve the same outlet temperature.
In summer the “Medium” power setting may give adequate hot water.
In some winter conditions, it may be necessary to select the inner or outer spray pattern only of
your shower handset. This will ensure correct operation of the shower with a slightly lower flow rate.
Effect of Other Water Devices on Incoming Water Supply
Your shower is designed to stabilise temperature changes caused by water pressure
fluctuations. These can result from toilets being flushed or taps being turned on and off.
When this happens your showering temperature will be held within a controlled band, provided that
the minimum pressure required by the shower is maintained.
Your shower requires a minimum operating pressure of 69kPa (0.7 bar, 10 psi).
At pressures above 69kPa (0.7 bar, 10 psi) it will minimise temperature fluctuations as detailed
above. If the water pressure falls below 69kPa (0.7 bar, 10 psi) it is likely that the pressure switch
w
ill turn off the power to the heating elements, resulting in a cold shower.
This will be indicated by the “Low Pressure” light illuminating.
HOW YOUR EXPRESSIONS 550S SHOWER WORKS