A pressure relief device (PRD) is a small but vital safety feature of an electric shower. If one goes, how can it be replaced?
Pressure relief devices (also known as pressure relief valves, and shortened to PRD or PRV) are small but vital safety features of electric showers.
If water is unable to be fully discharged through the shower head, pressure can build up in the heater tank, which could prove to be dangerous. In such situations the PRD will blow, allowing this pressure to escape. As a result, you may notice a small leak from the bottom of the shower body.
Blown PRDs need replacing. Before this, however, you should establish the cause of the PRD blowing in the first place to prevent the problem from reoccurring. If the original fault is not addressed, the new PRD will blow immediately upon installation as well. Common causes are:
- Shower head blocked with limescale and debris. An easy way to unblock a shower head is to use a good descaler.
- Kinked or damaged shower hose, or one that has collapsed inside. Unfortunately, in these cases, the hose will need replacing.
- Less commonly, but not unheard of, is a sudden increase in the cold mains supply.
Fitting a pressure relief device is a straightforward process, but you must follow all safety guidelines or consult a trained plumber/electrician. Electricity and water supplies to the shower must be off before proceeding. Our video below gives an overview of the process:
From our video, general instructions are as follows:
- After following all necessary safety precautions, take off the front cover to the shower.
- The pressure relief device will be located near to the outlet pipe (possibly right at the bottom). It may or may not be fixed on with screws.
- Unscrew the PRD if applicable, not forgetting to also take out the old O'ring left inside if it doesn't come out with the PRD.
- Place the new O'ring (supplied with the new PRD) into the opening and then screw on the new PRD if applicable. You may need a little force in order to push the device in initially, but don't use excessive pressure. The new PRD will have a small rubber ball inside; this is absent from the old device as it would have blown out.
- Restore the front cover and water/power supplies to the shower. Test as needed.
Please note that the design of the 828000450 PRD has now changed which is explained in the product link above. The fitting process is largely the same. In the revised version, a burst disc fits where the o-ring was situated previously. The burst disc replaces the rubber ball method of failure.
We offer a great value descaler to help with blocked shower heads, one of the leading causes of PRDs blowing.
You can also see our article here: Video: Common problems with electric showers