Concealed Shower System: Essential Fittings and Costly Mistakes

Introduction to Concealed Shower Systems.

Concealed shower systems deliver a sleek, minimalist look by hiding all plumbing behind the wall and exposing only the trim, arm and handset. They’re ideal for modern bathrooms, creating uninterrupted tile runs and freeing up shelf space. However, the hidden nature of these installs means every connection, fitting and bracket must be spot‑on before the wall is closed up.

A concealed shower comprises a mixer valve body, which blends hot and cold feeds and routes them to your shower arm (for an overhead head) and handset rail. Behind the scenes you’ll need isolation valves, check valves, pipework, drop‑ear elbows, adapters, hoses and a trim kit—all fitted at precise heights and depths. Get any of these wrong—set the valve too shallow, omit an isolation valve, solder poorly or forget to pressure‑test—and you risk water damage, expensive re‑work and ruined tile finishes.

In this guide, we’ll walk through the core fittings every concealed installation requires, break down the main valve types, cover additional components (elbows, hoses, trim), and finish with the most common—and most costly—mistakes to avoid.

Essential Fittings for Your Shower System

New Bathroom Installation By Step-Ahead Renovations LTD

Shower Valve Types

1. Thermostatic Mixer Valve

   • Maintains a constant temperature, preventing scalds.

   • Requires three ports (hot, cold, mixed outlet).

   • Cartridge depth behind finished wall must allow 35–40 mm clearance for the trim plate.

2. Manual (Pressure‑Balanced) Mixer Valve

   • Simpler mechanism—turn handle to blend feeds.

   • Two or three ports depending on shower + hand‑set configuration.

   • Less expensive but doesn’t lock temperature under fluctuating supply pressures.

3. Diverter Valve

   • If you want a single control to switch between overhead head and handset.

   • Can be built into the mixer (3‑way) or as a separate unit inline after a dual‑outlet mixer.

Additional Necessary Components

• Isolation Valves (Ball Valves): Fit on both hot and cold inlets, so you can service the mixer without draining the entire system.

• Non‑Return (Check) Valves: Installed immediately after each isolation valve to stop backflow and protect your water heater.

• Pipework: Use 15 mm copper, CPVC or PEX for feeds:

  • Copper with compression fittings (olive and nut).

  • CPVC solvent‑weld joints or PEX with crimp rings.

• Drop‑Ear Elbows / Wall Elbows: Brass elbows with mounting lugs hold the shower arm and handset outlet at the correct depth. These fix to a timber dwang or plastic box bracket between studs.

• Shower Arm Adapter: A ½″ BSP male threaded adapter that screws into the drop‑ear elbow, allowing your chrome shower arm to screw on flush with the finished wall.

• Riser Rail Outlet: A ½″ BSP female swivel connector mounted in its own bracket, feeding the flexible hose to your handset rail.

• Flexible Shower Hose: Standard ½″ BSP‑to‑½″ BSP braided hose (usually 1.5 m long) connects the outlet elbow to the handset.

• Trim Kit & Sealing Plate: The visible handles, escutcheon and decorative plate. Always check the manufacturer’s required behind‑wall depth (commonly 35–40 mm) before setting your valve.

Common Mistakes to Avoid When Installing

• Incorrect Valve Depth

  • If the mixer sits too deep, the trim won’t cover the hole; too shallow and the cartridge can’t engage fully. Always dry‑fit the trim plate against your finished tile or plasterboard before fixing the valve body.

• Skipping Isolation Valves

  • Without ball valves on each feed, any maintenance means shutting off water to the whole house. Ball valves cost pennies but save hours of inconvenience later.

• Omitting Check Valves

  • Backflow between hot and cold feeds can overheat your boiler or scald users. Always install a check valve directly after each isolation valve.

• Poor Joint Preparation

  • Solder joints with flux residue, un‑deburred edges or olives that aren’t seated properly will leak slowly behind walls. Clean, deburr and fully insert pipes; tighten compression nuts finger‑tight plus half a turn with a wrench.

• Misaligned Drop‑Ear Elbows

  • Elbows that aren’t square to the finished wall mean shower arms sit at an angle or the handset can’t reach the rail. Use a spirit level and measure from your final wall plane when fixing elbows.

• Skipping the Pressure Test

  • Always pressure‑test at least 3 bar for 15 minutes before boarding over. Hidden leaks only get discovered once tiles are down—resulting in demolition and re‑tiling costs.

• Wrong Pipe Material

  • Don’t substitute with generic polyethylene. Use PEX, CPVC or copper approved for UK potable water. Non‑compliant materials can fail regulations and damage finishes.

• Forgetting an Access Panel

  • Concealed mixers need access for cartridge swaps and valve servicing. Plan a discreet access panel or make the top tile removable. Otherwise, any repair means hacking into your brand‑new wall.

Conclusion

Careful planning, the right fittings and a methodical approach will ensure your concealed shower installation is clean, durable and trouble‑free. Follow this checklist, avoid the common pitfalls, and you’ll deliver a premium, leak‑proof shower that delights customers—and stands the test of time.