KB Heating & Plumbing repairs combi boilers of all makes across Cardiff, Penarth, Caerphilly and the Vale of Glamorgan, usually on the same day. KB Heating & Plumbing is Gas Safe registered (registration number 516445), based at 13 Wyfan Place, Cardiff CF14 3DT, with 20 years of trade experience and a 24/7 service. Call 07812 510121.
Why combi boiler faults hit harder
A combi boiler heats your radiators and your hot water from the same unit, with no hot water cylinder. When it fails, you usually lose both heating and hot water at once. Combi boilers are the most common type in Cardiff flats and terraced houses, so they make up a large share of the repairs KB Heating & Plumbing carries out.
Common combi boiler faults
- Heating works but no hot water, or hot water works but no heating. This often points to the diverter valve.
- Hot water that runs hot, then cold, then hot again.
- Pressure that keeps dropping, from a leak, a faulty pressure relief valve or a flat expansion vessel.
- The boiler locking out with a fault code.
- Kettling or banging, often caused by limescale from Cardiff’s hard water.
- A gurgling stop in freezing weather, caused by a frozen condensate pipe.
- Weak hot water flow at the taps, from a blocked plate heat exchanger.
How KB Heating & Plumbing repairs a combi boiler
The engineer reads the fault code and tests the parts that commonly fail on combi boilers: the diverter valve, plate heat exchanger, pump, fan, gas valve, flow sensor and circuit board. The system pressure and expansion vessel are checked at the same time.
You get the diagnosis and a price before the repair starts. Common parts are carried in the van, so most combi repairs are finished in a single visit, and the boiler is tested on both heating and hot water before the engineer leaves.
Repair or replace?
Repair is usually the right answer. If the boiler is very old, parts are no longer made, or the repair would cost a large share of a new boiler, KB Heating & Plumbing will tell you honestly and can quote for a boiler replacement so you can compare.
Combi boiler repair cost in Cardiff
The cost depends on the fault and the part. The price is confirmed before any work starts.
Combi boiler repair FAQs
My combi has hot water but no heating. What is wrong?
The most common cause is a sticking or failed diverter valve. A faulty thermostat, timer or pump can cause the same symptom.
How do I top up the pressure on a combi boiler?
Find the filling loop under the boiler, open it slowly until the gauge reads about 1 to 1.5 bar, then close it. If the pressure keeps dropping, there is a leak or a faulty part, and the boiler needs repairing.
Can you repair my combi at night or at the weekend?
Yes. See emergency boiler repair, available 24/7.