Below is a basic overview of faults you may experience with Electric Showers, Mixer Showers (both Manual and Thermostatic) and Power showers, together with some tips which might be helpful. This doesn't cover all faults, as some showers are more complex than others, but should be sufficient for most cases.

Electric Showers


Manual Mixer Showers


Thermostatic Mixer Showers


Power Showers


 Electric Showers

Electric showers use water from the cold mains, and are heated via a heating element (much like a kettle) inside the box on the wall.

See our article: Video: Common problems with electric showers



Common FaultPossible Remedies
No flow at all from the showerIsolating valve closed - check and open if required
Solenoid valve fault - replace solenoid coil or valve (sometimes as part of flow valve)
Low flowIsolating valve not open fully
Excessive limescale build up in heater tank (see Electric Shower Tips below)
Blocked handset or hose - clean or replace
Drop in cold supply water pressure
Flow valve faulty - replace
Completely cold water onlyRCD tripped - check fuse box and reset
Problem with power supply to the shower - check pull cord switch
Blocked filter - check and clean
Thermal switch failed - check continuity and replace if necessary
Water temperature fluctuating hot and coldOther outlets being used whilst showering ie taps turned on or toilet flushed - ensure no
other outlets are used during shower
Blockage in shower head or hose - clean shower head and check for kinks/blockages in hose
Limescale build up in heater tank - replace heater tank (see Electric Shower Tips below)
Oversensitive thermal switch - replace thermal switch
Only lukewarm waterLow water pressure - check isolating valve is open and the filter is clean
Pressure switch microswitch faulty - replace microswitch
One of the elements in the heater tank has failed (see Electric Shower Tips below)
Water leaking from bottom of the shower and only cold water through the headPressure relief device blown (usually due to blockages in heater tank, handset or hose) - locate cause of fault, remedy, and replace PRD
Unit works fine, but no indicator lightReplace neon assembly
Push button on/off showers only - unit starts, but flow stops after a second or twoInner section of button assembly on front cover not reaching the latching switch properly,
therefore not engaging it - replace either button or cover
Latching switch faulty - replace

Electric Shower Tips

  • If the temperature is fluctuating, you can see if it is a limescale issue by trying this - put the plug in the bath or cover over shower waste. Remove shower head, and start the shower on the hottest setting and turn temperature dial from hot to cold several times. If it is a limescale build up issue, some limescale will be ejected into the water. In most cases the complete heater tank would need to be replaced anyway, as you cannot descale most heater tanks.
  • If you are only getting lukewarm water - it may be that one of the heater tank elements has failed. To test this, turn shower on to medium heat. Is there any heat? If no heat, the first element is probably faulty. If there is heat, turn to highest heat setting - does it get hotter? If not, the second element is probably faulty. In most cases the complete heater tank would need to be replaced anyway, as most manufacturers do not supply elements separately.
  • Checking whether a thermal switch is faulty - you need to perform a continuity test on it using a multimeter- as the thermal fuse will display no visual indicators of its fault. Disconnect the wires from the thermostat to be tested. Place the probes on each side of the thermal switch and switch it to Ohms. The reading for a working thermal fuse should be zero- meaning that this thermal fuse is working perfectly and doesn't need to be replaced. Set the function switch on the multimeter to 'Ohms'. Connect one lead to each side of the thermal switch. If the reading comes up as Zero, the thermal switch is not faulty and working as it should. If you get any current. it means that it is faulty and needs replacing.

 


 

Manual Mixer Showers

Manual mixer showers take the hot and cold supplies and just act as a means to mix the water to achieve the temperature requested by you. The shower cannot adjust temperature itself.

See our article: Video: Common problems with mixer showers


Common FaultPossible Remedies
Only hot or cold water coming from showerBlockage in hot or cold water supply - check pipework for blockages
Check filters - clean if necessary
Fluctuating or reduced flow rateCheck the shower head, hose, and filters for any blockages
Airlock or partial blockage in pipework
Hot or cold flow drops off when another outlet turned onThe boiler is not able to supply more than one outlet with hot water at once - do
not use any other outlet ie flush toilet, whilst using the shower
Insufficient mains cold water pressure - so other outlet takes the water from the
shower
N.B. To solve these issues, install thermostatic mixer, which adjusts the water, to
ensure that there are no hot or cold fluctuations due to draw off from other outlets
Low flow or no flow from shower headBlocked filter - inlet filters and clean if necessary
Inlet check valve faulty - check and clean or replace if necessary
Spray plate blocked - clean and descale if required
Stop valve closed or partially closed - ensure both hot and cold stop valves are open
Temperature issuesHave you just replaced the cartridge? If YES - reset the maximum temperature. If NO - see below
Check the shower head, hose, and filters for any blockage
Airlock or partial blockage in pipework
Faulty thermostatic cartridge - renew cartridge
Water dripping/leaking from the shower head after turned offIs it for a short period - If YES - a small amount of water may be retained in the fitting after the shower control has been turned off, and may drain after a few
minutes. This is normal. Changing the angle of the shower head to point
downwards may speed up this process.
If NO - see below
Check that the pressures are not in excess of the specifications for product
Cartridge seals damaged - replace seals
Faulty cartridge - replace cartridge
Shower control 'thumps' when another tap is turned off suddenlyInlet check valve faulty - check and clean or replace if necessary
Shower runs cold during shower
Boiler running out of hot water
Shower flow control stiff to operateShower internals stuck with limescale or debris - clean, descale and service or
replace cartridge if necessary

 


 

Thermostatic Mixer Showers

Thermostatic mixers are designed to adjust the temperature of the shower itself, so it maintains a constant and safe temperature.

See our article: Video: Common problems with mixer showers


Common FaultPossible Remedies
Only hot or cold water coming from showerBlockage in hot or cold water supply - check pipework
Blocked filters - check filters
 
Fluctuating or reduced flow rate
 
Blocked head or inlet filters - check the shower head, hose, and filters for any blockages
Airlock or partial blockage in pipework - check pipework for obstructions
No flow at allCold supply failure - if the for some reason the cold water is interrupted, the thermostat would
come into force and shut off the water to prevent scalding
Fluctuating temperature hot and coldIs it on a combi? - if NO - check hot supply for blockages or interruption in supply.
If YES - if the shower head is blocked, or hose kinked this would created back pressure,
causing the combi to cycle - clean and descale shower head
Also, if you have just replaced the shower head, check that there are enough holes and
holes are large enough. If possible replace like for like shower head
Temperature issuesHave you just replaced the cartridge? If YES - reset the maximum temperature as per
manufacturers instructions.
If NO - see below
Check the shower head, hose, and filters for any blockage
Airlock or partial blockage in pipework - check the pipework and that stop valves are fully
open
Faulty thermostatic cartridge - renew cartridge
Water dripping/leaking from the shower head after turned offIs it for a short period? - if YES - a small amount of water may be retained in the fitting after
the shower control has been turned off, and may drain after a few minutes. This is normal.
Changing the angle of the shower head to point downwards may speed up this process.
If NO - check that the pressures are not in excess of the specifications for product
Cartridge seals damaged - renew seals
Faulty cartridge - renew cartridge
Shower flow control stiff to operateShower internals stuck with limescale or debris - clean descale and service or replace
cartridge if necessary
Shower runs cold during showerBoiler running out of hot water


Mixer Shower Tips

  • Lubricants - Silicone based lubricants must only be used on the rubber seals. Oil based or other lubricant types may cause rapid deterioration of seals.
  • Cleaning of Chrome components - chrome plated parts should be cleaned using a milder washing up detergent or soap solution, rinsed and then wiped dry with a soft cloth. Many household cleaners contain abrasive and chemical substances, and should not be used for cleaning plated or plastic fittings. Do not use descalents on metal or plastic parts.

 


 

Power Showers


Power Showers are usually tank fed. There is a box on the wall which mixes the water then pumps the water to increase the flow rate.

Common FaultPossible Remedies
No flow from showerWater not reaching shower - check isolating valves are open
RCD has tripped - check fuse and reset if necessary
No power getting to the shower - check wiring and transformer
Faulty PCB - replace PCB
Faulty flow valve or solenoid valve - replace
The pump/motor is not working or poor flow from shower headBlown fuse - check and reset or replace as necessary
No power getting to the shower - check wiring and transformer
Faulty PCB - replace PCB
Faulty flow valve or solenoid valve - replace
If the pump is making a grinding or loud noise - bearings may be worn -
replace pump assembly
If the pump making a noise, with black carbon dust inside the cover -
carbon brushes may be worn - remove all of the carbon dust and replace pump.
Some manufacturers supply just the brushes, but would not recommend it
Dripping from the shower headMixer valve seals faulty - replace mixer valve seals or replace whole
mixer valve or cartridge

 


Important Disclaimer

As per the manufacturers we deal with, most shower repairs, especially involving electricity, require a fully qualified professional. National Shower Spares accept no responsibility for any damage to property or personal injury caused by following the advice above.


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