Boiler pressure and heating faults
Most combi boilers run best between 1 and 1.5 bar of pressure — too low and the heating cuts out, too high and the pressure relief valve can discharge. A plumber checking a heating fault will usually look at pressure, check for trapped air in radiators (bleeding), and check the pump and diverter valve before assuming a full boiler fault.
Hard water and your plumbing
In hard water areas, limescale builds up inside pipes, taps, showerheads and boiler heat exchangers over time, gradually reducing efficiency and flow. A plumber working in a hard water area may recommend a water softener or scale inhibitor as part of a boiler installation, particularly for a system that's expected to last 10+ years.
Background checks and identity verification
Before booking, it's worth checking a plumber's trading history and identity, not just their registration — a landline or verifiable business address and reviews referencing specific jobs are stronger signals than a mobile number and a van sign alone.
How plumbing quotes work
Describe the job, including whether it's an emergency, a planned repair, or a full installation, and mention access — under a suspended floor is very different from behind fitted units. Plumbers use this for an initial estimate; the final price is usually confirmed once they've seen the fault or the space in person.
Three steps to hiring the right plumber
First, check they're registered with a WaterSafe scheme (or Gas Safe too, if the job needs it) and ask for the registration number. Second, get a written quote that separates labour from parts. Third, ask what happens if the job uncovers a bigger problem — a good plumber will tell you before continuing, not after.
Heat pumps and eco-friendly heating options
Some plumbers also work on or alongside heat pump installations, though this is often a joint job with a heating engineer for the heat pump unit itself. If you're considering moving away from a gas boiler, it's worth asking whether your plumber does this work directly or partners with someone who does.
What affects the cost
Cost depends on the scope of the job, how accessible the pipework is (under a floor vs behind a wall), whether parts need to be sourced specially, and whether the job is planned or an emergency call-out. A simple tap or valve replacement is usually quick and low-cost; anything requiring pipework to be rerouted, or walls/floors to be opened up, costs more partly because of the making-good work afterwards.
Common plumbing myths, busted
"A dripping tap is just cosmetic" — left long enough it wastes real water and can damage the fitting further. "Any handyman can fit a boiler" — boiler work involving gas connections legally needs a Gas Safe engineer, not just a plumber. "Bleeding a radiator fixes all heating faults" — it only helps with trapped air, not pressure or pump issues.