If you have hot water but no heating in Maldon, that tells us something useful straight away. Your boiler or heating system can still produce hot water, but something is stopping heat from reaching the radiators.
Start with the simple checks first. Your thermostat, programmer or radiator controls may be the cause. If those look correct, the problem could involve a diverter valve, pump, motorised valve, circulation issue or another part of the boiler or heating system.
This guide explains what you can safely check and when to arrange a professional boiler repair in Maldon.
Quick answer:
If your hot water works but the radiators stay cold, first check that central heating is switched on, the thermostat is asking for heat and the radiator valves are open. If you have a combi boiler, a faulty diverter valve is one possible cause. Pumps, heating controls and circulation problems can also stop the radiators heating. If the basic checks do not solve it, book an engineer.
In This Guide
Hot Water But No Heating in Maldon: What Does It Mean?
This symptom is different from losing both heating and hot water.
If your taps or shower still produce hot water, at least part of the system is operating.
The problem is more likely to involve the central-heating demand, water flow to the radiators or a component that controls where the boiler sends its heat.
Possible areas include:
- the room thermostat
- the heating programmer
- smart-heating controls
- radiator valves
- a combi boiler diverter valve
- a heating pump
- motorised valves on some systems
- poor water circulation
- a boiler sensor or control fault
Why This Symptom Helps With Diagnosis
Tell your engineer that the hot water still works.
That information helps separate this problem from a complete boiler shutdown.
If both services have stopped, our wider no heating or hot water in Maldon guide is the better place to start.
Hot Water But No Heating? Safe Checks to Make First
Start outside the boiler.
You can check the heating controls and radiators without removing the boiler casing.
| Check | What to Look For | What to Do |
|---|---|---|
| Thermostat | Is it asking for heat? | Raise the target temperature above the current room temperature. |
| Programmer | Is central heating switched on? | Check the schedule, time and heating mode. |
| Boiler mode | Is it set to hot-water-only or summer mode? | Select heating mode using the manufacturer's instructions. |
| Radiator valves | Are TRVs or manual valves closed? | Make sure radiators you want heated are turned on. |
| Boiler pressure | Is the pressure below the normal range? | Check the instructions for your exact boiler. |
| Fault display | Is there a code or warning? | Take a photo before resetting anything. |
1. Check Your Thermostat
Make sure the room thermostat is actually asking the heating to come on.
Temporarily set the thermostat several degrees above the current room temperature.
If you use a wireless thermostat, also check:
- the battery level
- whether the display is working
- whether the thermostat shows a heating demand
- whether the receiver appears to be responding
A thermostat problem can stop the heating from coming on while the boiler still responds normally when you open a hot tap.
2. Check Your Programmer or Heating Schedule
Check whether central heating is scheduled to run.
Look at:
- the current time
- the current day
- heating on/off periods
- holiday mode
- summer mode
- manual overrides
Power cuts, battery changes and accidental button presses can alter heating schedules.
3. Is the Boiler Set to Hot-Water-Only Mode?
Some boilers let you turn central heating off while leaving hot water available.
This is useful during summer, but it can cause confusion when colder weather returns.
Check the boiler display and controls to make sure central heating is enabled.
Vaillant lists hot-water-only settings as one of the first things to check when the hot water works but central heating does not.
See the Vaillant guide to common boiler problems.
4. Check the Radiator Valves
Make sure the radiators have not been turned off.
Thermostatic radiator valves are often turned down during warmer months.
If every radiator valve is shut, the central heating may appear not to be working even though the boiler is available to provide heat.
Ideal Heating also recommends checking that individual radiators are turned on when you have hot water but no central heating.
See the Ideal Heating boiler troubleshooting guide.
5. Check the Boiler Pressure
Look at the pressure gauge or digital pressure reading.
Use the manufacturer's instructions to check whether the cold pressure is within the correct range.
If the reading is too low, our live low boiler pressure in Maldon guide explains how to decide whether the system simply needs repressurising.
If you keep having to restore the pressure, use our separate boiler losing pressure in Maldon guide.
Hot Water But No Heating From a Combi Boiler
A combi boiler produces both central heating and hot water from the same appliance.
When you open a hot tap, the boiler responds to the hot-water demand. When your thermostat asks for heat, the boiler should send heat towards the radiators.
If hot taps work normally but none of the radiators become warm, possible causes can include:
- incorrect heating settings
- a thermostat or controls problem
- a faulty diverter valve
- a pump or circulation problem
- a sensor or internal boiler fault
The symptom gives your engineer a useful starting point, but it does not prove which part has failed.
Could a Faulty Diverter Valve Cause Hot Water But No Heating?
Yes, on a combi boiler a diverter valve is one possible cause.
The diverter valve controls where heat is directed when the boiler receives a demand for central heating or hot water.
Vaillant lists hot showers working while the radiators remain cold as one symptom that can point towards a faulty diverter valve.
You can read the Vaillant diverter valve guide.
Do not try to replace a diverter valve yourself.
The valve sits within the boiler and diagnosis requires access to the appliance. A Gas Safe engineer should confirm the fault before any boiler component is replaced.
Other Signs of a Diverter Valve Problem
Depending on the boiler, you may also notice:
- lukewarm hot water
- hot water only working when the heating is on
- radiators getting warm when you only want hot water
- heating failing while hot taps work normally
These symptoms can have other causes too, so an engineer should test the boiler before changing the valve.
Could the Heating Pump Be the Problem?
The heating system needs water to circulate through the radiators.
If a pump is not moving water correctly, the boiler may still produce hot water while the central heating performs poorly or does not heat at all.
A circulation problem does not automatically mean the pump itself has failed.
Air, valves, electrical faults or restrictions elsewhere in the system can produce similar symptoms.
One Cold Radiator or Every Radiator?
This distinction matters.
| What You See | Possible Area to Check |
|---|---|
| Every radiator is cold | Thermostat, programmer, boiler controls, pump, diverter valve or heating circulation. |
| Only one radiator is cold | Radiator valves, trapped air or an issue local to that radiator. |
| Radiator cold at the top | Trapped air may be present. |
| Radiator cold at the bottom | Sludge or poor circulation may be restricting heat. |
| Only one heating zone is cold | Zone controls, thermostat or motorised valve may need checking. |
Only One Radiator Is Cold?
If every other radiator heats normally, the boiler may not be the main problem.
Check the radiator valves first.
A radiator that is cold at the top can contain trapped air, while a radiator that stays cold at the bottom can indicate sludge or poor flow.
Vaillant provides more homeowner checks in its radiator troubleshooting guide.
Should I Bleed the Radiators?
Bleeding can help if a radiator contains trapped air.
A common sign is a radiator that stays cold near the top while the lower section becomes warmer.
Do not automatically bleed every radiator just because the whole heating system has stopped.
If every radiator is completely cold while hot water works normally, check the heating controls first.
Remember that bleeding radiators on a sealed system can reduce boiler pressure. Check the gauge afterwards.
Hot Water But No Heating With a System or Conventional Boiler
Homes with system or conventional boilers can have a separate hot-water cylinder and more external heating controls than a combi-boiler system.
The heating and hot-water circuits may use:
- separate thermostats
- motorised valves
- a circulation pump
- a programmer
- a hot-water cylinder thermostat
- zone controls
This means the cylinder can sometimes still become hot even when the radiator circuit has a control or circulation problem.
If the programmer and thermostat look correct, an engineer may need to test the valves, pump and controls.
Hot Water Works but the Boiler Does Not Respond to the Thermostat?
Turn the target room temperature above the current room temperature and watch the heating controls.
If nothing changes, the thermostat or communication between the thermostat and heating controls may need attention.
Check wireless thermostat batteries before booking an engineer.
Do not remove electrical control covers unless the manufacturer's homeowner instructions specifically allow it.
Hot Water But No Heating With a Boiler Fault Code?
Take a photograph of the boiler display.
The fault code may help identify whether the boiler has detected a circulation, sensor, pressure or another problem.
Do not order a replacement part from the code alone.
Use our live boiler fault code in Maldon guide for the next step.
Hot Water But No Heating After a Boiler Reset?
If resetting the boiler briefly restores heating but the problem returns, do not make repeated resets your solution.
A recurring fault needs diagnosis.
If the boiler enters lockout, our live boiler lockout in Maldon guide explains what to record before you reset it.
Hot Water But No Heating and Boiler Keeps Turning Off?
Tell your engineer if the boiler starts the heating and then quickly stops.
Pressure, circulation, overheating, controls and other faults can all contribute to repeated shutdowns.
See why a boiler keeps turning off in Maldon for more detail.
Hot Water But No Heating and Strange Boiler Noises?
A new noise can give your engineer another useful clue.
Listen for:
- banging
- gurgling
- whistling
- humming
- buzzing
- repeated clicking
Our boiler making strange noises in Maldon guide explains what different sounds can indicate.
What If the Boiler Will Not Fire for Heating?
If the hot-water demand works but the boiler never starts when the thermostat requests central heating, first check the heating mode and controls.
If those are correct, the heating demand may not be reaching the boiler or another component may be stopping the central-heating sequence.
For broader ignition troubleshooting, see why a boiler won't fire up in Maldon.
When Hot Water But No Heating in Maldon Needs an Engineer
Arrange a professional check if:
- all radiators remain cold after checking the thermostat and programmer
- hot water works normally but the heating never starts
- the boiler shows a recurring fault code
- the heating works only temporarily after a reset
- the boiler repeatedly goes into lockout
- you suspect a diverter valve fault
- the heating pump does not appear to be circulating water
- one heating zone repeatedly fails
- the boiler makes unusual noises when heating is requested
- you are unsure whether the appliance is safe
Hot Water But No Heating in Maldon?
If the hot taps work but the radiators stay cold after the basic checks, Boilers 4 Essex can find the cause.
Our Gas Safe registered engineers diagnose boiler and central-heating faults throughout Maldon and the surrounding CM9 area.
What Will a Heating Engineer Check?
The checks depend on your type of heating system and what happens when you request central heating.
An engineer may check:
- the thermostat and heating controls
- boiler settings
- system pressure
- the heating demand signal
- radiator valves
- the circulation pump
- water flow through the heating system
- the diverter valve on a combi boiler
- motorised valves on relevant systems
- fault-code history
- boiler sensors and controls
The aim is to find which part of the heating sequence has failed before recommending replacement parts.
How Much Does a Hot-Water-But-No-Heating Repair Cost?
The price depends on the cause.
A thermostat or simple controls problem can cost very differently from a diverter valve, pump, motorised valve or internal boiler repair.
For general pricing information, see our live boiler repair cost in Maldon guide.
Heating Fault Repairs in Maldon and CM9
Boilers 4 Essex provides boiler and heating fault diagnosis throughout Maldon and surrounding CM9 areas.
We can investigate:
- hot water working but no central heating
- all radiators staying cold
- combi boiler diverter valve faults
- thermostat and heating-control problems
- circulation and pump faults
- recurring boiler lockouts
- heating-related fault codes
- boilers that switch off when heating starts
If you have hot water but no heating in Maldon, visit our Boiler Repairs in Maldon page to arrange an engineer.
Related Maldon Boiler Repair Guides
- No heating or hot water in Maldon
- Boiler not working in Maldon
- Boiler fault code in Maldon
- Boiler lockout in Maldon
- Boiler pressure too low in Maldon
- Boiler losing pressure in Maldon
- Boiler keeps turning off in Maldon
- Boiler making strange noises in Maldon
- Boiler won't fire up in Maldon
- Boiler repair cost in Maldon
Important Gas Safety Advice
Having hot water but no central heating is normally a heating-system fault rather than a gas emergency.
If you smell gas or suspect a gas leak, call the National Gas Emergency Service on 0800 111 999.
Open doors and windows. Shut off the gas supply at the meter if you know how to do so safely.
Do not remove the boiler casing or attempt to repair diverter valves, pumps, gas components or internal controls yourself.
For official advice, see the HSE gas-safety guidance for homeowners.
Hot Water But No Heating in Maldon: Frequently Asked Questions
Why do I have hot water but no heating?
Start by checking the thermostat, heating programmer, boiler mode and radiator valves. If these are correct, possible causes include a diverter valve, pump, circulation fault or another heating-control problem.
Can a diverter valve cause hot water but no heating?
Yes. On a combi boiler, a faulty diverter valve can allow hot water to work while preventing heat from reaching the radiators. An engineer should confirm the fault before replacing the valve.
Why are all my radiators cold but the hot water works?
If every radiator is cold, check the thermostat, programmer and boiler heating mode first. If the controls appear correct, a pump, diverter valve, circulation or another heating-system fault may need checking.
Why is only one radiator cold?
If the other radiators work normally, the problem may be local to that radiator. Check its valves. Trapped air or sludge can also prevent a radiator heating correctly.
Should I bleed my radiators if I have no heating?
Bleeding can help when radiators contain trapped air, especially when they are cold at the top. If every radiator is completely cold, check your thermostat and heating controls first.
Why does my combi boiler give hot water but not heat the radiators?
A combi boiler can still respond to hot-water demand while having a separate problem with its heating demand. Possible causes include controls, a diverter valve, circulation, the pump or another boiler fault.
Does hot water but no heating mean I need a new boiler?
No. Many faults that cause this symptom can be repaired. An engineer should diagnose the problem before you consider boiler replacement.
Can Boilers 4 Essex fix hot water but no heating in Maldon?
Yes. Boilers 4 Essex provides boiler and central-heating fault diagnosis and repairs throughout Maldon and the surrounding CM9 area.
Hot Water Working but Radiators Still Cold?
If the thermostat, heating schedule and radiator valves all look correct, get the heating fault properly diagnosed.
Boilers 4 Essex can find the cause and explain the repair needed.
Helpful Official Guidance
- Vaillant: Hot water but no heating
- Vaillant: Boiler diverter valve faults
- Ideal Heating: Boiler not working troubleshooting
- Vaillant: Why is my radiator not working?
- HSE: Gas safety advice for homeowners
Last updated: 13 August 2026. Heating systems vary depending on boiler type, controls and installation. Always follow the user instructions supplied for your exact appliance.
