Electric showers are great, but they do go wrong occasionally. At Kitamura we repair all types of showers. A lot of people seem to confuse “power showers” with “electric showers”. They aren’t the same. An electric shower simply heats the water, the water goes through the shower under simple water pressure itself. That is where power showers differ. They still heat the water, but they also have a motor assisted water pump, which acts like the turbocharger in an engine, where a little amount of pressure is converted into massive pressure by an impeller.
We recently got called out to a faulty Mira Essentials electric shower. These were made in 2000, and this one was suffering from random pressure drops, and weak output. Here’s a shot of under its cover, I’ve labelled its parts which I’ll explain below:
A. Water input w/filter
The cold water input, with filter. This is a gauze filter that filters any silt in the water. If not filtered out it could collect in the water heater, and cause failure, or blockage in other parts of the shower system.
B. Water impeller.
This is not electrically assisted as in a power shower, but it helps to keep the shower running if there is momentary pressure drop due to something else being used in the water system like a tap.
C. Power and Temperature knob with flow solenoid
This is the ON/LOW/MED/HIGH selector, which works in tandem with two microswitches, and two heating elements. When the shower is switched on, the electric flow solenoid opens, allowing water flow. In the LOW position the water heater is fully switched off, and the water is cold as all microswitches are open. In the MED position, one microswitch is closed, so one of the elements is active, and in HIGH both switches are closed, making the heater operate at full wattage, in this case 4.2kw.
D. HIGH microswitch
This is the microswitch that operates the second element by turning the temp knob to HIGH as above.
E. Temperature knob.
This works by varying the amount of water that gets through to the output. By reducing the speed of water flowing through the heater, it makes the water hotter, and increasing it makes it colder. If the Mode selector is HIGH and the Temp knob turned all the way to HOT, the heater would be shut off by the TCO (Thermal CutOut) on the heater as the water temperature is too high, which will cause scalding to the person using it, and also damage to the heater.
F. Neon indicator PCB
This board contains the neon indicators for Power, Overheat, and Low Pressure. It also contains resistors to prevent premature wear of the neon bulbs, they are run from 240v and don’t last long, especially the POWER indicator, as that is on as long as the mains is on.
G. Mains input terminal block
Self explanatory, this is where the mains is wired in to the shower. In this case the shower had its own switch and fuse in the consumer unit, so we didn’t have to turn the electricity off to the customer’s entire house while we worked!
H. Water heater with TCO (Thermal Cut Out)
Here’s where the water is heated before going to the shower head. The two elements are individually controlled by the microswitches previously mentioned in C, controlled by the MODE knob. The heater contains a thermal cutout so that the elements are turned off if the water gets too hot. Once the water reaches a certain colder temperature, the thermal cutout switch turns the elements back on.
The thermal cutout is normally only activated if the temperature knob is on HIGH, and the TEMP knob set to its hottest, which is minimal water flow, as mentioned in E.