Thermostatic Shower Buying Guide

There's nothing better than a rejuvenating shower. Perfect for a relaxing soak after a long day or to wake you up in the early morning, these nifty devices are often the focal feature of our bathrooms thanks to their ease of use and mobility benefits. So, when it comes to choosing the perfect shower for your home, it can be confusing navigating the many types of styles available. That's why we're here to make life a little easier by singing the praises of the thermostatic shower.

But what exactly is a thermostatic shower and how does it work? Here at Plumbworld, we've created a guide to help you understand everything about these innovative showers, from how they work to how to install them...

What is a Thermostatic Shower?

A thermostatic shower is a type of mixer shower featuring a thermostatic valve that maintains a constant water temperature. These types of showers are fed via a property’s hot and cold water supply, with an internal valve to mix them. So, if your shower is prone to running either too hot or cold or even consistently fluctuates in temperature, a thermostatic shower could be your answer!

The thermostatic valve is what truly makes this shower so unique, as it mixes both hot and cold water together to a consistent and predetermined temperature. Doing so, this prevents scalding and cold shocks, making these innovative showers perfect for families with young children or the elderly.

How is a Thermostatic Shower different from Mixer Showers?

Although a manual mixer shower will mix hot and cold water to a set temperature, unlike a thermostatic shower, it can't react to sudden changes in temperature. A thermostatic shower instantly reacts to a change in water temperature and adjusts the water accordingly to get it back to the pre-set temperature. This avoids the threat of scalding or cold shock, making them perfect for avoiding injury.

How is a Thermostatic Shower different from Electric Showers?

Thermostatic showers differ from an electric shower in a number of ways, the main difference being that they rely on a mains water supply to operate, whereas a combination of water pressure and temperature allows a thermostatic shower to function.

Unlike a thermostatic shower, electric showers have their own heating element, which is usually seen in a box on the wall, so they only use a cold water supply, whereas thermostatic showers need hot and cold water.

Want to know more about different shower types? Read more: What Are The Different Types of Showers?

How does a Thermostatic Shower Work?

Thermostatic showers store water at a high temperature before mixing it with cold water in a valve to a temperature that you have pre-set. 

Each thermostatic shower has the following core elements:

  • Element: sensitive to the temperature of the water flowing through it, the element increases or decreases in size.
  • Piston: working in tandem with a spring, the piston moves across the hot and cold water entry points to regulate the water temperature as the element increases or decreases. The piston is key to maintaining a constant temperature.
  • Temperature control: this is the part of the valve that you can see and control - like with all showers. The control moves the piston, changing the hot and cold water mix.

These elements work together to keep the temperature you have selected at a constant and can be easily adjusted where necessary.

Thermostatic Shower Valves

Shower valves are a crucial component of the thermostatic shower. Along with mixing the water together, the valve will instantly react to changes in water temperature, an ingenious feature that makes a thermostatic shower the most reliable and controller-friendly.

Thermostatic shower valves will also shut down immediately should the cold water supply fail, perfect for avoiding injury to the user, such as scalding by hot water. This built-in safety system marks thermostatic showers out among other types.

Here at Plumbworld, we stock a variety of thermostatic shower valves, so you’re guaranteed to find a valve that suits your bathroom décor.

Bar Valve: Bar shower valves feature slimline controls and a compact size, making them an excellent choice for small bathrooms. Easy to fit, these valves are often the most affordable of the thermostatic valves and come in a variety of finishes and materials.

Concealed Valve: Concealed shower valves ooze minimalism in design, boasting a sleek and discreet style. All the shower workings sit conveniently behind a plate fitted to the wall or behind the wall itself. Here, only the controls, riser and showerhead are on display, meaning less bulk on the wall!

Exposed Valve: Exposed shower valves add a classy and designer-inspired look to your bathroom where all of the controls and shower workings sit externally on the wall. This allows you to switch between two water outlets, for example, such as an overhead shower and a shower handset. If you have a larger bathroom, this valve can help fill in wall space.

Traditional Valve: Traditional shower valves bring a classic design to your bathroom, offering beautifully old styling. Including level and cross handles, these valves are a combination of bar and exposed valve designs.

How to Fit a Thermostatic Shower

Step one: turn off your stopcock

No matter where your starting point is (you may already have a mixer shower and separate pipes for a shower), you will need to turn off your stopcock to isolate the water supply and drain the water from your pipes.

Step two: decide where to take your hot and cold water from

If you are fitting the thermostatic shower above a bath, then you will be able to tap (or tee) into the tap water supplies. However, if you are installing a thermostatic shower in a shower cubicle or enclosure, you can tee into the nearest piping, which is often under your flooring.

Step three: run the hot and cold water pipes towards the shower

Once you’ve tapped into the water supply and turned off the water, you’ll need to run the pipework toward the shower. Make sure you check your thermostatic valve instructions to ensure the hot and cold water supplies are on the correct sides (hot is usually on the left).

Plastic piping can be easier to work with and may be run under your floorboards and up behind stud walls. To prevent plastic pipes from deforming through use or heat, use pipe inserts at any joints.

Include a shut-off valve on your hot and cold pipes as close to the shower as possible. It can be easier to tighten compression joints on copper piping than plastic, so try inserting some copper pipe at the end of the plastic.

Switch the water supply back on to check for any possible leaks and put plastic pipe covers - or stop ends - over the ends of the piping.

Step four: flush the piping

Thermostatic shower valves can be damaged by any dirt that is in the water flowing through it, so be sure to flush your new pipework. You can do this while checking for any leaks by removing the stop ends from your pipes and running water through them, then simply hold a bucket underneath the pipes to catch any dirt. Be sure to switch the water supply off via your stopcock once you’re done.

Step five: mark and cut your pipes

Get your thermostatic valve and hold it next to your outlet pipes flat against the wall. Then, with a pencil, mark the amount of pipe that’s needed to allow the valve to sit flush against the shower wall (this is best done before installing tiles or bathroom wall panels). Once this is complete, cut the excess piping. You can use a saw or a tubing/pipe cutter for this.

Step six: drilling time

After you’ve cut your pipes, you can drill the holes to attach the thermostatic valve. Mark where the valve will sit and the screw points, and then you drill the holes. We suggest using a diamond-tipped drill head, as it will work best on walls and tiles.

Step seven: fit a compression olive

To ensure a water-tight seal in the thermostatic valve, place a compression olive (sometimes called a collapsible olive) in each valve inlet and secure it in position by screwing the retaining nut with one turn.

Step eight: align the thermostatic valve

Now for the main event - attaching the thermostatic valve! Align the valve with the hot and cold pipes. Then, make sure they fully slide into the pipes. Screw your shower valve onto the wall and tighten the retaining nuts, this is best done with an adjustable spanner. Turn the water supply back on via the stopcock to check for any possible leaks at the inlet.

Step nine: fit the rest of your shower

Once the valve is fitted, you can install the rest of your shower, including the riser pipe or hose, and your shower head or handset.

For a fixed riser pipe, it may be supplied oversized to suit various bathroom heights, so you may need to cut it down to size. First, measure the depth of the recess that the pipe will sit in on the thermostatic valve. Then, do the same on the bracket that will secure the top of the riser pipe.

With some double-sided sticky tape, put it on the top bracket at the height you want it to be above the valve. Next, measure between the bottom of the bracket and the top mounting nut on your thermostatic valve. Add this measurement to the ones you’ve already made and cut the pipe to this length.

When cutting a riser pipe, do not use a saw - a pipe cutter is best and will provide a clean cut.

Test that the riser pipe fits based on your measurements and that it is vertical with a spirit level. If it is, mark the top bracket mounting holes, drill them, and then plug them. You can now fit the riser pipe - tightening the nuts, where necessary - then, fit and screw on your shower head.

Turn the water back on and check for any leaks. Check the thermostatic valve works by making sure the shower temperature remains constant're done!

If you're looking for more inspiration or advice on showers, take a look at the following posts - Rainfall Showers and Rainfall Shower Heads - Benefits of Dual Shower Heads - What are the Different Types of Showers?

We love seeing your bathroom and kitchen makeovers and sharing them on our Instagram page - if you've had a Plumbworld renovation, tag us in your photos to be featured!

We would love to see, so why not share your favourite designs on social media with us?

Find us at:

Facebook | Twitter | Instagram | TikTok | Pinterest

Alternatively, sign-up to our newsletter for the latest offers, newest product launches and advice.

Are you planning a new bathroom or kitchen makeover? Shop online with Plumbworld for guaranteed lowest prices and next day delivery options.

Don’t forget to check out the rest of our blog for more bathroom and kitchen advice.