New: Electric Shower Leaking from Bottom? How to Replace the PRD

⚠️ SAFETY FIRST: READ BEFORE STARTING

Working on electric showers is dangerous. You are dealing with a high-voltage appliance (240V) and water.

• ISOLATE POWER: Always turn off the electricity at the main consumer unit (fuse box) and pull the isolation cord before removing the shower cover.

• VERIFY DEAD: Use a voltage tester to ensure no power is reaching the unit.

• LEGALS: In the UK, major electrical work in bathrooms is "Part P" regulated. If you are not a competent person or are unsure of these tests, stop and consult a Part P qualified electrician.

• DISCLAIMER: You follow these guides at your own risk. This site and its authors are not liable for any injury, loss, or damage caused by your repairs.

If water is suddenly leaking from the bottom of your electric shower, the Pressure Relief Device (PRD) has likely operated. This is a safety feature designed to burst if the pressure inside the heating tank gets too high, preventing the tank from exploding. In this guide, I'll show you how to replace a burst PRD and—more importantly—how to find out why it blew in the first place so you don't waste money on a second replacement.

Buy electric shower parts on Ebay UK here

Need a Multimeter for testing try on Ebay UK here

Why did my PRD burst? A PRD doesn't usually fail on its own. It "blows" to protect you. Before replacing it, check for these common causes:

• Blocked Shower Head: Limescale buildup is the #1 cause of back-pressure.

• Kinked Hose: Even a slight twist in the shower hose can trigger the PRD.

• Incorrect Shower Head: Using a head not designed for electric showers (like a "water-saving" or power-shower head) can cause too much restriction.

A PRD costs about £5–£10, but a plumber will charge £100+ to replace it

How to Replace the PRD (Step-by-Step)

CLEAN YOUR SHOWER HEAD BEFORE REPLACING

Isolate Power & Water: Turn off the pull-cord and the mains water.

Remove the Shower Head: Do this first! If you replace the PRD but leave a blocked head on, the new PRD will blow the second you turn it back on.
Unclip the Outlet Pipe: Most PRDs are located where the hose attaches to the unit.
Swap the Part: Pull out the old plastic housing and push in the new one (ensure the O-ring is seated).
Test: Run the shower on COLD first to prime the tank, then check for leaks.

Remove the cover from the shower unit first 

and now you can see the outlet pipe attached to the heater element 

and water tank 

you are looking for something that looks similar to below 

a little outlet attached to the main outlet 

size PH1 PRD retaining screws

here is is removed you can buy these very cheap 

the seal at the hole of this outlet pipe is set to burst at a certain pressure to prevent 

water overheating in the main heater element tank 

so replace it if it is burst 

Below i am taking off the heater outlet pipe make sure you replace o-ring seal if needed 

ive replace the outlet pipe and now i am doing up the retaining screws size PH2

                          here is a video below of me doing this 

Tools Needed

• PH1 & PH2 Screwdrivers

• Replacement PRD (Very cheap on eBay see link below)

Step-by-Step Replacement

1. Safety: Turn off the power and water.

2. Locate: The PRD is attached to the bottom of the heater tank outlet pipe.

3. Remove: Undo the two small PH1 screws.

4. Inspect: Look at the small rubber ball or disc inside. If it’s missing or pushed out, it’s burst.

5. Install: Push the new PRD into place and tighten the screws. Ensure the O-ring is clean to prevent minor leaks.

Buy these PRD from Ebay UK here 

Pro-Tip: Preventing a PRD Blow-Out

A PRD doesn't just "fail" on its own; it is forced to blow by back-pressure. If you don't fix the source of that pressure, your new part will burst within seconds of your next shower.

How to Descale Your Shower Head (The 1-Hour Fix)

Limescale is the #1 killer of PRDs. If you live in a hard water area, you should do this every 3 months:

1. The Vinegar Soak: Unscrew your shower head and place it in a bowl of white vinegar.

2. Wait: Leave it for at least one hour (or overnight for heavy buildup). The acetic acid will dissolve the calcium carbonate.

3. Brush: Use an old toothbrush to clear the rubber nozzles.

4. Flush: Run water through the head backwards (from the nozzle side) to push out any loose grit before reconnecting it to the hose.

The "Pin-Hole" Test

Before you install your new PRD, hold your shower head up to the light. If more than 10% of the holes are blocked, the back-pressure is likely still too high. Clean it again or replace the head entirely.