Intermittent Heating? We'll Track Down Why It Comes and Goes in Coventry

Why Heating Behaves Intermittently

Faults that come and go are rarely random — they follow patterns, and those patterns are the best diagnostic tool available. Common causes include:

• Thermal faults — a component that fails only when hot. PCBs, sensors and motorised valve actuators can all work when cold and cut out as the system warms, which is why the heating often dies part-way through a run.
• Sticking valves and pumps — a diverter valve that occasionally sticks in the wrong position, or a pump whose bearings are on the way out, produces heating that works on some cycles and not others.
• Dropping pressure — a sealed system with a small leak holds pressure for days, then crosses the lockout threshold. The heating then cuts out until someone repressurises it, and the cycle repeats.
• Control and wiring faults — loose connections, a thermostat with failing batteries, or corroded terminals can interrupt the call for heat unpredictably, especially where cables run through cold lofts or damp areas.
• Air in the system — trapped air shifts around as the system heats and cools, so radiators work after bleeding and go cold again days later.
• Overheat cut-outs — restricted circulation from sludge or a partially blocked plate exchanger can trip a boiler's overheat protection, shutting it down until it cools, then letting it run again.

Why Intermittent Faults Worsen

The patterns tend to shorten. A valve that sticks once a month starts sticking weekly; a thermal cut-out that trips occasionally trips on every run. Meanwhile a system repeatedly losing pressure has a leak that is weeping water into somewhere it should not be, and a boiler cycling on overheat protection is being stressed each time. Diagnosing an intermittent fault early is easier than diagnosing it later, simply because the failure is less entrenched.

How We Approach an Intermittent Fault

We start with your observations, because they matter enormously: does it fail when cold or hot, on heating only or hot water too, at particular times of day? We then check the pressure history and look for the leak that a dropping gauge usually implies, inspect radiator bleed points and pipework for air, and test the thermostat, programmer and wiring for solid connections. Where a valve or pump is suspect we exercise it repeatedly and monitor its behaviour, and we check whether the boiler is tripping on overheat — which points to restricted circulation rather than the boiler itself. The visit may not always reproduce the fault while we are there, but a systematic elimination usually narrows it to one component or one section of the system.

Repairs Within Our Scope

We repair the water-side and electrical causes of intermittent heating; we are not Gas Safe registered and never carry out gas work. That includes replacing failing pumps and motorised valve actuators, repairing thermostat and control wiring, repressurising systems after locating and fixing leaks, bleeding and balancing radiators, and power-flushing systems choked with sludge that restrict circulation. Where a boiler sensor or PCB is implicated and accessible, we can replace it. We do not carry out gas work — if the diagnosis points to the burner, gas valve or ignition, we explain our findings and refer you to a trusted Gas Safe registered engineer we work closely with.

Keeping Notes That Help

With faults that come and go, a week of simple notes is worth more than a guess. Note the time the heating dropped out, whether the pressure gauge had fallen, whether any error code showed, and whether the hot water was affected too. Photograph the gauge and display if you can. Bring those notes to our visit and we can often go straight to the likely component rather than testing everything in turn — which saves you time and money.

Booking and What to Tell Us

Get in touch with your boiler's make, model and age, whether it is a combi or a system with a cylinder, and the pattern you have noticed. Same-day attendance may be possible but is never guaranteed. We work across the West Midlands, quote the full cost before starting any repair, and will not leave until either the fault is fixed or you know exactly what the next step is — including a Gas Safe referral where the evidence demands one.