No Hot Water But Heating Works - What to Check in Your Altrincham Home

Published September 2026 | Boiler Repair

This checklist walks you through every step of diagnosing why your boiler is producing heat for your radiators but delivering cold water from your taps and shower - and what to do about each cause in the right order. Catching the fault early and knowing when to call in a Gas Safe registered engineer can save you several hundred pounds and a very unpleasant morning.

Quick Visual Checks Anyone Can Do

These are the first things our engineers ask about when a homeowner in Altrincham calls with the classic "heating's fine but no hot water" problem. Work through them without any tools in under ten minutes before anything else.

1. Check your boiler pressure gauge. The gauge on most combi boilers should sit between 1 and 1.5 bar when the system is cold. If it has dropped below 0.8 bar, low pressure can prevent the domestic hot water circuit from working even while central heating carries on normally. Look for the dial or digital readout on the front panel. If it is low, you can repressurise the system yourself using the filling loop - your boiler manual covers the exact steps, and it typically takes less than two minutes.
2. Check the hot water temperature setting. It sounds obvious, but the domestic hot water temperature dial gets knocked more often than you would think. It should normally be set between 55 and 65 degrees Celsius. If someone has turned it down to the minimum by accident, the water from the tap may feel barely warm or completely cold.
3. Check the timer and programmer. If your boiler has a separate hot water programme - which many Altrincham homes with older system boilers do - make sure the hot water schedule is actually switched on. It is easy to knock the hot water programme off while adjusting the heating times, especially on older dial-style controllers.
4. Look for any error codes on the display. Modern boilers from manufacturers like Worcester Bosch, Vaillant, and Baxi all display fault codes when something is wrong. Take a photo of any code showing on the screen - even if it means nothing to you, it tells an engineer exactly where to start. You can also run it through the Voltrade GoFIX diagnostic tool for an instant interpretation before booking anyone out.
5. Check whether other taps produce hot water. If one tap runs cold but the rest of the house has hot water, the problem is with that tap or its pipework rather than the boiler. If none of your taps produce hot water while the radiators are warm, that confirms the fault sits in the boiler's domestic hot water circuit itself.
6. Feel the pipework near the boiler. When a diverter valve is stuck in the heating position - the most common cause of this problem by some margin - the pipes leading to your hot water circuit tend to feel noticeably cooler than the pipes feeding your radiators. You can check this safely by touching the outside of the pipes with the back of your hand. Do not touch any pipe that may be very hot.

Monthly Maintenance Tasks

Monthly checks take about five minutes and are the single most effective thing a homeowner can do to keep boiler repair costs down. These apply to any property across Greater Manchester, whether you have a combi, system, or conventional boiler.

• Check and note your boiler pressure. Write it down each month. A system that regularly loses pressure has a slow leak somewhere in the circuit. Finding it early is far cheaper than dealing with the damp, mould, or secondary damage a hidden leak causes over several months.
• Run hot water for 30 seconds from each tap. This keeps the pipework active and helps you spot gradual temperature changes before they develop into a complete loss of hot water. If one outlet is noticeably cooler than the rest, flag it early.
• Check the condensate pipe is clear and undamaged. The white plastic pipe that exits through an external wall or into a drain can collect debris or freeze in cold weather. In Greater Manchester, winter temperatures drop low enough to freeze exposed condensate pipes regularly - and when that happens, most modern boilers lock out entirely and stop producing hot water.
• Bleed your radiators if any feel cold at the top. Trapped air in the system increases the strain your boiler is working under and can indirectly affect how the hot water circuit performs over time.
• Listen to your boiler when it fires. A healthy boiler fires up cleanly and quietly. Banging, gurgling, or a low rumbling on ignition are early signs of a problem worth investigating before it develops into a no-hot-water situation.

Annual Professional Checks You Should Book

Some boiler faults can only be properly diagnosed and fixed by a Gas Safe registered engineer. In the UK, it is a legal requirement that anyone working on gas appliances holds current Gas Safe registration - always ask to see their card before any work begins on your boiler. It is not optional, and anyone working without it should not be in your home.

An annual boiler service typically costs between 80 and 120 pounds and should include all of the following:

• Inspection and cleaning of the heat exchanger for lime scale build-up. This is a particular concern in parts of Altrincham and the surrounding Greater Manchester area where water hardness is higher, as scale accumulation is one of the main reasons hot water performance degrades over time.
• Testing of the diverter valve operation. This is the component most commonly replaced when heating works but hot water does not, and an experienced engineer will test its movement and sealing during any annual service.
• Cleaning and inspection of the condensate trap.
• Checking burner pressure and gas rate to confirm the boiler is operating within its designed parameters.
• Testing all safety controls and sensors, including the domestic hot water thermistor - a failed thermistor commonly causes the boiler to produce no hot water while central heating continues to operate normally.
• Flue gas analysis to confirm efficient and safe combustion.

If your boiler has not been serviced in over a year and you have already lost hot water, book a service as your first call. It combines the diagnosis and the maintenance in one visit, which typically saves both time and money compared to a separate call-out.

Warning Signs That Need Immediate Attention

Some symptoms, when they appear alongside a loss of hot water, mean you should stop using the boiler and call an engineer the same day rather than working through a checklist.

• A smell of gas or sulphur near the boiler. Turn the gas off at the meter immediately and call the National Gas Emergency line on 0800 111 999. Do not attempt to investigate the source yourself, and do not operate any electrical switches.
• Loud banging, kettling, or persistent rumbling from the boiler. Kettling - a sound similar to a boiling kettle - typically means significant lime scale has built up on the heat exchanger. Left untreated, it can cause the heat exchanger to crack. Replacing a cracked heat exchanger commonly costs between 300 and 600 pounds on mid-range boilers, and can reach higher on some models - far more than the cost of catching it early.
• The boiler fires and then immediately shuts off repeatedly. This short-cycling behaviour points to a sensor fault, pressure issue, or flue blockage that needs hands-on diagnosis. Running a boiler that keeps short-cycling can cause additional component damage and should not be left.
• Visible water staining or dampness around the boiler casing. Any sign of a water leak near the boiler needs a Gas Safe engineer to assess it. Water near gas components is not something to monitor and see how it develops.
• Your carbon monoxide detector activates. Get everyone out of the property immediately, leave doors and windows open if it is safe to do so, and call 999. Carbon monoxide is colourless and odourless - if the alarm sounds, take it seriously every time.

Your Maintenance Schedule

A simple calendar approach keeps your boiler in good shape without it feeling like a burden. Here is how we recommend Altrincham homeowners structure their routine.

Monthly - 5 minutes

• Record boiler pressure and compare to last month
• Run hot water from all taps and check temperature
• Check condensate pipe is clear and undamaged
• Listen for any new or unusual noises during a firing cycle

Every 6 months

• Bleed radiators if any are cold at the top
• Turn all thermostatic radiator valves (TRVs) through their full range to prevent them seizing up
• Check the boiler display for any stored or intermittent fault codes

Annually

• Book a full service with a Gas Safe registered engineer
• Ask the engineer to specifically test the diverter valve if your boiler is over 8 years old
• Review any boiler cover or home emergency policy to confirm it is still active and appropriate for your boiler age

When you notice a problem between scheduled checks
Run the Voltrade GoFIX diagnostic tool before booking anyone out. It walks you through a guided fault-finding process and helps you understand whether the issue is something you can address yourself or whether you need a Gas Safe engineer on site - which means you arrive at that conversation already knowing the key facts.

Checklist Questions

Why does my heating work but I have no hot water in my Altrincham home?

The most common cause is a faulty diverter valve inside your combi boiler. This valve controls whether the boiler's output goes to your radiators or your hot water taps. When it sticks or fails, it typically defaults to the central heating position - your radiators stay warm while every tap in the house runs cold. A Gas Safe engineer can test the valve and replace it if needed, with parts and labour typically costing between 150 and 300 pounds depending on the boiler make and model. A secondary cause worth checking is a failed domestic hot water thermistor, which gives the boiler incorrect temperature readings and prevents it from heating your water supply.

Can I fix a no hot water problem myself without calling an engineer?

How much does it cost to repair a boiler with no hot water in Greater Manchester?

The cost depends on what the fault turns out to be. A diverter valve replacement typically runs to between 150 and 300 pounds including parts and labour. A faulty thermistor or flow sensor is often less - commonly between 80 and 150 pounds. If the heat exchanger has cracked due to lime scale damage or age, costs can reach between 400 and 700 pounds, and on some older boilers a replacement boiler starts to look more economical than a major repair. Getting a proper diagnosis first - using the Voltrade GoFIX tool for an initial assessment and then an engineer visit for confirmation - means you know what you are dealing with before committing to any repair work.