No Hot Water? Quick Checks & When to Call a Plumber

By The FixDelivered Team · Updated 2026-08-07 · 7 min read

There’s nothing quite as frustrating as stepping into the shower, turning the tap, and being met with icy cold water. A sudden lack of hot water can throw a spanner in your daily routine, but often, the cause is simpler than you think. This guide will walk you through common reasons why your hot water might not be working, provide clear DIY checks you can perform safely, and crucially, advise you on when it’s time to call in a professional plumber.

Common Reasons for No Hot Water

Whether you have a gas boiler, an electric immersion heater, or a combination of both, several issues can lead to a cold shower. Understanding the potential culprits can help you diagnose the problem.

Pilot Light Out (Gas Boilers): A common issue for older gas boilers. If the pilot light is extinguished, the boiler can't ignite the main burner to heat water.
Low Boiler Pressure (Sealed Systems): Combi and system boilers often require a specific pressure range (typically 1-1.5 bar). If it drops too low, the boiler may shut down as a safety measure.
Thermostat Settings: Both your boiler thermostat and any separate hot water cylinder thermostat need to be set correctly. They might have been accidentally turned down or off.
Programmer or Timer Issues: Your boiler's programmer might be set to the wrong time, or the hot water schedule might be off. Sometimes a simple reset is all that's needed.
Power Supply Problems: A tripped fuse, a switch accidentally turned off, or a power cut can obviously stop your boiler or immersion heater from working.
Frozen Condensate Pipe (Combi Boilers): During colder months, the external condensate pipe on a combi boiler can freeze, causing a blockage and shutting down the boiler.
Immersion Heater Failure: If you rely on an immersion heater, its heating element might have failed, or its internal thermostat could have tripped.
Diverter Valve Fault (Combi Boilers): In a combi boiler, the diverter valve switches between heating your radiators and providing hot water. If it gets stuck or fails, you might get heating but no hot water, or vice-versa.

DIY Checks for Boilers and Immersion Heaters

Before you panic, try these simple, safe checks. You don't need to be a plumbing expert, just a careful homeowner.

1. Check the Power Supply

It sounds obvious, but it's often overlooked. Ensure your boiler or immersion heater is receiving power.

Boiler: Check that the boiler's power switch (usually a fused spur near the boiler) is on. Also, check your home's fuse box or consumer unit for any tripped circuit breakers or blown fuses related to your heating system.
Immersion Heater: Verify the dedicated switch for your immersion heater is on, and check the fuse box for any tripped switches.

2. Check Your Boiler Pressure (Sealed Systems Only)

For combi or system boilers, locate the pressure gauge. It should typically read between 1 and 1.5 bar when the system is cold. If it's below 1 bar:

Locate the filling loop (a flexible metal hose with two valves, usually underneath your boiler).
Slowly open both valves until the pressure gauge rises to between 1 and 1.5 bar.
Close both valves securely and check for any leaks.
If the pressure frequently drops, or you're unsure, do not repeatedly top up; call a professional.

Safety Note: Never over-pressurise your system. If you're unsure how to repressurise, or if the pressure drops again quickly, contact a qualified engineer.

3. Review Thermostat and Programmer Settings

Incorrect settings are a frequent cause of no hot water.

Boiler Thermostat: Ensure the hot water setting (if separate from heating) is turned up sufficiently.
Hot Water Cylinder Thermostat: If you have a hot water cylinder, check its thermostat. It's usually a dial on the side of the tank. Set it to around 60°C for optimal hot water and to prevent bacterial growth.
Programmer/Timer: Check that your heating programmer or smart thermostat is set to provide hot water at the times you expect. Has it been accidentally overridden or set to 'off'? Try turning it off and on again, or resetting it to factory defaults if you know how.

4. Check the Pilot Light (Gas Boilers Only)

If you have an older gas boiler, the pilot light may have gone out. Consult your boiler's manual for specific instructions on how to relight it. There's usually a clear viewing window to check if it's lit.

Safety Warning: If you smell gas, do NOT attempt to relight the pilot light. Turn off your gas supply at the meter, open windows and doors, and call the National Gas Emergency Service (0800 111999) and a Gas Safe registered plumber immediately. If the pilot light repeatedly goes out, it indicates an underlying fault that requires professional attention.

5. Thaw a Frozen Condensate Pipe (Combi Boilers Only)

If you have a combi boiler and it's cold outside, your condensate pipe (a plastic pipe, usually white or grey, leading from your boiler to an outside drain) might be frozen. Your boiler may display a fault code.

Locate the frozen section (often where it exits the wall or just before the drain).
Gently pour warm (not boiling) water over the frozen section, or apply a hot water bottle or heat wrap.
Do not use a naked flame or anything that could damage the pipe.
Once thawed, your boiler should reset and start working. You may need to press a reset button on the boiler itself.

When to Call a Professional Plumber

While these DIY checks can resolve many common issues, there are times when professional help is essential. Never attempt to repair gas appliances yourself or delve into complex electrical or internal boiler components unless you are qualified to do so.

You should call a qualified plumber or heating engineer if:

Your DIY checks haven't resolved the issue.
You suspect a gas leak (as above, immediate action required).
Your boiler is displaying a persistent fault code that you can't clear.
You hear unusual noises (banging, gurgling, whistling) coming from your boiler or pipes.
There are visible leaks from your boiler or hot water cylinder.
You're unsure about any step or feel uncomfortable performing the checks.
Your hot water cylinder is leaking or has stopped heating water despite power being on.

For reliable, local help, you can get a plumber now through FixDelivered. We connect you with qualified plumbers in your area, and our booking fee is refundable if no plumber is found for your job.

What to Expect When Calling a Plumber

When you call a professional for a 'no hot water' issue, here's a rough guide to what you might expect in terms of service and costs (prices are approximate for 2026 and vary by region and plumber):

Call-Out Fee: Typically, plumbers charge a call-out fee, which can range from £70-£150 for non-emergency visits during standard hours. For emergency emergency plumbers near you outside of normal hours, this could increase to £150-£300 or more. This fee often covers the first hour of diagnosis.
Hourly Rates: Beyond the initial call-out, hourly rates usually fall between £50-£90.
Diagnostics: The plumber will systematically diagnose the fault, which might involve checking electrical components, gas pressures (for Gas Safe engineers), and internal boiler parts.
Parts: Any required parts (e.g., a new diverter valve, pressure sensor, thermostat) will be an additional cost.
Quotation: A reputable plumber will provide a clear explanation of the fault and a quote for the repair before proceeding with any work. With FixDelivered, the plumber’s callout fee is agreed upfront and paid directly to them, ensuring transparency from the start. You can learn more about how FixDelivered works.

Always ensure that any plumber working on a gas appliance is Gas Safe registered. You can ask to see their ID card.

Preventative Maintenance for Your Hot Water System

To minimise the chances of waking up to cold water, consider annual servicing for your boiler. A qualified engineer can identify potential issues before they become major problems, ensuring your system runs efficiently and safely. For immersion heaters, periodic checks for leaks or unusual noises can also help.

Losing hot water is never ideal, but by systematically checking the common culprits and knowing when to seek professional help, you can often resolve the issue quickly and safely. Remember, safety always comes first, especially when dealing with gas or electricity. When in doubt, call a qualified plumber. FixDelivered makes it easy to find a trusted, local professional ready to help you get your hot water back on.

Frequently asked questions

Why has my hot water stopped working but heating is fine?

This often points to an issue specific to your hot water system. For combi boilers, it could be a faulty diverter valve. For systems with a hot water cylinder, check the cylinder thermostat or a faulty zone valve. If you have an immersion heater, its element or thermostat might be the problem.

How much does it cost to get a plumber for no hot water?

In 2026, expect a call-out fee of £70-£150 during standard hours, potentially £150-£300+ for emergencies. Hourly rates usually range from £50-£90, plus the cost of any parts needed for the repair.

Can I fix no hot water myself?

You can certainly perform basic checks like power supply, thermostat settings, boiler pressure top-up, or thawing a frozen condensate pipe. However, for anything involving gas, complex electrical issues, or internal boiler components, always call a Gas Safe registered engineer.

What's a frozen condensate pipe and how do I fix it?

A condensate pipe carries waste water from your combi boiler. In cold weather, it can freeze, causing a blockage and stopping your boiler. You can safely thaw it by pouring warm (not boiling) water over the frozen section until the blockage clears.

Need a plumber now? Tell us your emergency and FixDelivered will find and confirm an available local plumber near you, usually within the hour.

Written by the FixDelivered Team. Reviewed by Rupert Lowe, Editor. Last updated 2026-08-07.