Common causes
- A faulty diverter valve — on a combi boiler, this switches flow between heating and hot water; if it's stuck, one or the other stops working.
- A blocked plate heat exchanger — sludge or scale can restrict flow so badly the boiler can't heat water properly, sometimes triggering it to overheat instead. This was exactly the fault we found and fixed on an Ariston Evo combi in Stourbridge — read the case study.
- A failed immersion heater — on electric and Pulsacoil-type boilers rather than standard gas combis. We diagnosed and replaced a corroded immersion heater on a Gledhill Pulsacoil in Erdington — see that job too.
- A faulty thermistor or PCB fault — less common, and something that needs proper diagnostic equipment to confirm rather than guesswork.
Not just standard gas combis
A lot of general "boiler repair" companies focus almost entirely on mainstream gas combi brands. We also work on electric and Pulsacoil-type systems, which have their own specific failure points — worth mentioning if you've been told elsewhere that your system is too unusual to fix.
Pricing
Diagnosis and first hour: £99. Parts — such as a plate heat exchanger or immersion heater — are quoted before fitting.