Shower Cold No Hot Water: Causes & Fixes

Finding yourself standing under a shower that’s suddenly ice-cold with no hot water coming out is one of the most frustrating household problems in the UK. Whether you’re a homeowner rushing to get ready for work or a landlord dealing with an unhappy tenant, the search term “shower cold no hot water” usually means you need fast, clear answers. 

In this guide, I’ll explain the most common reasons this happens and — more importantly — give you safe, step-by-step fixes you can try yourself before calling in a professional.

Why Is My Shower Cold & I Have No Hot Water Anywhere in the House?

If your shower is cold and no hot water is coming from any tap in the property, the problem is almost always with the central heating system or the hot water cylinder rather than the shower itself.

Broken or Tripped Immersion Heater (Electric Immersion Heater Fault)

An immersion heater is the electric element inside your hot water cylinder that heats the stored water.

Common causes:

• The immersion heater element has burned out (very common after 8–12 years)
• The thermostat inside the immersion has failed or is set too low
• The reset button (overheat cut-out) has tripped
• The timer or economy 7 controller is faulty or switched off

How to fix it yourself:

1. Check the immersion heater switch (usually next to the cylinder cupboard) is ON.
2. Locate the reset button — usually a small red button under the white plastic cover on top of the immersion boss. Press it firmly (you may hear a click).
3. Use a multimeter or test pen to check there is power reaching the immersion (only if you are competent).
4. If the reset keeps tripping or there is no power, the element or thermostat has failed — you will need a qualified electrician or plumber.

Frozen Condensate Pipe (Combi Boiler Only)

In very cold UK winters, the 32 mm or 40 mm plastic condensate pipe that runs outside from a condensing combi boiler can freeze solid.

How to fix a frozen condensate pipe:

1. Locate the white or grey plastic pipe leaving the boiler and going outside.
2. Pour warm (not boiling) water from a kettle slowly over the frozen section until it thaws.
3. Reset the boiler once water flows freely again.
4. Insulate the pipe with lagging afterwards to prevent it happening again.

Boiler Pressure Too Low or Too High

Most combi boilers need the pressure gauge to read between 1 and 1.5 bar when cold.

How to fix low boiler pressure:

1. Find the filling loop (usually a flexible silver hose or two taps under the boiler).
2. Slowly open the valve(s) until the gauge reaches 1.2 bar.
3. Close the valve tightly — a common cause of repeated pressure loss is a dripping filling loop.

Airlock in the Hot Water System

Air trapped in pipes can stop hot water reaching taps and showers.

How to clear an airlock:

1. Turn off the cold water supply to the cylinder (if you have one).
2. Attach a hose to the downstairs hot tap and connect the other end to the cold mains tap.
3. Open both taps fully for 30–60 seconds to force mains pressure backwards and push the air out.
4. Repeat on upstairs taps if needed.

Diverter Valve Failure (Combi Boiler)

The diverter valve switches the boiler between heating the radiators and heating hot water for taps/showers.

Symptoms of a stuck or failed diverter valve:

• Radiators get hot when you run a hot tap
• Hot water only works when the central heating is on
• No hot water at all but heating works fine

Fix: This almost always requires a Gas Safe engineer — the valve motor or the valve itself has failed and needs replacing (£250–£450 typical cost).

Thermostat or Motorised Valve Fault (System or Regular Boiler with Cylinder)

In homes with a hot water cylinder, a 2-port or 3-port motorised valve controls the flow of hot water from the boiler to the cylinder.

Common faults:

• Motorised valve stuck in “heating only” position
• Faulty thermostat on the cylinder
• Wiring or actuator head failure

Fix: Try turning the manual lever on the side of the valve to “MANUAL” temporarily — if hot water returns, the actuator or thermostat is faulty and needs replacing by a professional.

Why Is My Shower Cold But I Still Have Hot Water from the Taps?

If hot water comes out of the bath or sink taps normally but the shower stays cold, the issue is usually with the shower or mixer rather than the boiler.

Thermostatic Cartridge or Valve Failure in the Shower

Modern thermostatic showers have a cartridge that blends hot and cold to a safe temperature.

Signs of failure:

• Shower only runs cold even when set to maximum hot
• Temperature fluctuates wildly

How to fix:

1. Turn off water at the isolator valves (small screw slots on pipes to the shower).
2. Remove the shower handle and temperature knob.
3. Unscrew and replace the thermostatic cartridge (exact part depends on make — Aqualisa, Mira, Grohe, Triton, Bristan etc.).
4. Cost of cartridge usually £40–£120.

Blocked Shower Head or Hose

Limescale buildup (very common in hard-water areas like London and the South East) can block the hot side.

Fix: Soak the shower head overnight in white vinegar or a descaling solution, then scrub with an old toothbrush.

Anti-Scald Device or Flow Restrictor Stuck

Many showers have a small plastic restrictor or anti-scald ring inside — these can seize up.

Fix: Remove and clean or remove the restrictor completely (safe if you have a TMV elsewhere).

Broken Non-Return Valves or Check Valves

These small valves stop hot water flowing back into the cold pipe — if they fail, cold water can overpower the hot.

Fix: Replace the non-return valves (usually inside the shower valve).

How to Prevent “Shower Cold No Hot Water” Problems in the Future

• Have your boiler serviced every 12 months by a Gas Safe engineer (legal requirement for landlords)
• Insulate external condensate pipes with 19 mm thick foam lagging
• Keep boiler pressure checked monthly
• Fit a limescale reducer or water softener if you live in a hard-water area
• Replace immersion heater elements every 10 years as preventative maintenance
• Install a magnetic system filter (e.g., Magnaclean) to protect the diverter valve

When You Absolutely MUST Call a Gas Safe Engineer

You must call a Gas Safe registered engineer immediately if you notice any of the following:

• Any smell of gas
• Yellow or orange boiler flame (should be crisp blue)
• Black soot marks around the boiler
• Boiler keeps locking out with an ignition fault or flame failure code
• You suspect a carbon monoxide leak (headaches, nausea, black sooty marks)
• You have tried everything above and still have no hot water

Never attempt to repair gas appliances yourself — it is illegal and extremely dangerous.

FAQs

Can I still have a shower if my boiler is broken?

Yes — if you have an electric shower, it heats water independently and will still work. If you have a mixer shower fed from the boiler or cylinder, you’ll only get cold water.

Why does my hot water work in the morning but go cold in the evening?

This is classic hot-water cylinder recovery issue — the cylinder has run out of stored hot water after heavy use (multiple showers, baths, washing machine). A larger cylinder or upgrading to a combi/unvented system may be needed.

Will turning the boiler off and on again fix no hot water?

Sometimes yes — a simple power reset can clear a temporary lockout. Wait 30 seconds after switching off before turning back on.

Is it cheaper to fix the boiler or replace it when hot water stops working?

If the boiler is under 10–12 years old and the repair is under £400–£500, repairing is usually more cost-effective. Older than 12 years with a major fault (heat exchanger or PCB) — replacement is normally better long-term.

My tenant says the shower is cold but taps are hot — am I legally responsible as a landlord?

Yes — under the Homes (Fitness for Human Habitation) Act 2018, landlords must ensure a working hot water supply at all times. You must arrange a repair within a reasonable timescale (usually 24–48 hours for no hot water).

Stay warm, The Boilers2Go Team