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.
If you do need some advice or your fault is not listed below, we may be able to advise if you get in touch.
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: Common problems with electric showers
| 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
- 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: Common problems with mixer showers
| 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.
See our article: Video: Common problems with mixer showers
| 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
- 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 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.