No hot water, changing shower temperatures, low boiler pressure, or recurring fault codes? A combi boiler handles both home heating and hot water, so the symptoms help identify what needs professional diagnosis. Call to ask about repair options in your area.
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Combi boilers heat water on demand and also supply central heating. A problem may affect the taps, the radiators, or both—each pattern points to different checks.
Tell the person handling your call whether the fault happens at every hot-water tap, only during a shower, or when heating is running. The boiler's displayed fault code and pressure reading can also be useful.
Combi boiler not working? Call (888) 766-1474 and describe what still works and what has stopped.
A qualified technician needs to establish whether the fault lies in hot-water demand, heating circulation, combustion, controls, or another part of the system before recommending repair. Domestic hot water means the water coming from taps and showers; central heating means the radiators or heating zones.
If heating works but taps run cold, a technician may assess hot-water flow detection, the diverter valve, plate heat exchanger, and temperature sensors. A changing shower temperature is not proof that any one part has failed.
Low system pressure, an expansion-vessel issue, leakage, thermostat demand, or circulation problems can interrupt space heating. Repeated pressure loss needs investigation rather than ongoing top-ups.
Recurring lockouts may require checks of ignition, flame detection, venting, and controls. Work involving gas, combustion, electrics, or sealed equipment belongs with a qualified professional.
If you smell gas, leave the building and contact your gas utility or emergency services from a safe location. If a carbon monoxide alarm sounds, get outside and call emergency services. Do not repeatedly reset a locking-out boiler or remove its cover.
Specify whether the problem affects hot water at the taps, space heating, or both. Mention intermittent temperatures, pressure loss, and any fault code.
Call (888) 766-1474 and explain that you have a combination boiler.
Say whether heating, hot water, or both have failed; mention fault codes and any visible leak.
Provide your ZIP code or city so service availability can be checked.
Ask about assessment arrangements, potential diagnostic charges, and how repair pricing is determined.
A combination boiler is really two appliances sharing one burner and one heat-exchanger circuit.
On a heating call, the boiler circulates system water through radiators. Open a hot tap and the flow switch tells the diverter valve to swing priority to domestic hot water: system water is routed through one side of the plate heat exchanger while mains cold water picks up heat on the other side, arriving at the tap seconds later. Close the tap and the valve swings back.
That diverter valve is the hardest-working moving part in the boiler — it cycles every time anyone runs hot water. The plate heat exchanger's narrow waterways are the second weak point: in hard-water areas, limescale narrows them until hot water runs lukewarm or the boiler overheats and locks out.
Combi faults split cleanly by which job is failing.
Answers to common homeowner questions before arranging a combi boiler assessment.
The issue may involve a hot-water flow sensor, diverter valve, plate heat exchanger, or controls. A technician can check which part of the hot-water circuit is failing.
Unstable flow, limescale buildup, temperature sensors, or other control issues can affect hot-water delivery. Note whether it happens at several outlets or only one fixture.
Pressure below the manufacturer’s operating range can prevent normal operation. Repeated pressure loss may indicate leakage or another system fault; it should be investigated rather than continually refilled.
A lockout is a protective shutdown. Ignition, flame detection, venting, sensors, or system conditions may be involved. Repeated resets are not a repair.
Yes. A room thermostat, heating demand signal, diverter function, pump, or circulation issue may prevent radiator heating even when tap water remains hot.
Cost depends on the fault, boiler model, parts, labor, access, and any after-hours charges. Ask whether a diagnostic fee applies and request the repair scope and price before approving work.
Some leaks involve serviceable seals, valves, or pipe connections; others may involve major components. Turn off the appliance if safe to do so and request an assessment, especially if water is near electrical parts.
The decision depends on age, condition, parts availability, fault severity, repair cost, and hot-water demand. An accurate diagnosis is needed before comparing repair with replacement.
Often, yes. Lukewarm tap water with working heating usually traces to the plate heat exchanger or diverter valve — both are serviceable components. Descaling or replacing the plate exchanger and rebuilding or replacing the diverter are routine repairs, far short of a new boiler.
A sealed combi circuit holds only a few gallons, so even a tiny weep — a radiator valve gland, a joint, the pressure relief valve passing — shows on the gauge within days. The expansion tank can also be the culprit: if its diaphragm fails, pressure spikes when hot and dumps out the relief valve, then reads low when cold.
Startup failures, error codes, sensors, and electrical controls.
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Water leaks, persistent pressure loss, and pressure fluctuations.
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Seasonal inspections and preventive system care.
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Ignition, burner, heating-control, and no-heat problems.
View Service DetailsTell us whether taps, radiators, or both are affected. Have your ZIP code and any boiler fault code ready. Call to ask about combi-boiler assessment charges and availability in your area.
