Our website is open and shipping as normal. Read about COVID-19 here.

Fault Finder

Most types of showers have faults which are fairly standard for the type of shower you have.

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

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.

Common Fault Possible Remedies

No flow at all from the shower

Isolating valve closed - check and open if required

Solenoid valve fault - replace solenoid coil or valve (sometimes as part of flow valve)

Low flow

Isolating 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 only

RCD 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 cold

Other 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 water

Low 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 head

Pressure 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 light

Replace neon assembly

Push button on/off showers only - unit starts, but flow stops after a second or two

Inner 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

 

 

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.

Common Fault Possible Remedies

Only hot or cold water coming from shower

Blockage in hot or cold water supply - check pipework for blockages

Check filters - clean if necessary

Fluctuating or reduced flow rate

Check 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 on

The 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 head

Blocked 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 issues

Have 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 off

Is 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 suddenly

Inlet 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 operate

Shower 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.

Common Fault Possible Remedies

Only hot or cold water coming from shower

Blockage 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 all

Cold 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 cold

Is 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 issues

Have 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 off

Is 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 operate

Shower internals stuck with limescale or debris - clean descale and service or replace cartridge if necessary

Shower runs cold during shower

Boiler running out of hot water

Mixer Shower Tips

 

 

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 Fault Possible Remedies

No flow from shower

Water 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 head

Blown 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 head

Mixer 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.