Fault finding: what to check before you ring.

• Is the programmer actually calling for heat? Timers lose their schedule after a power cut, and smart thermostats lose it after a flat battery or a router change.
• Is the room thermostat set above the current room temperature, and does it have working batteries?
• Is there power to the boiler — a switched fuse spur near it, or a tripped breaker in the consumer unit?
• Is the system pressure gauge reading somewhere around 1 to 1.5 bar when the system is cold? Below half a bar, most boilers refuse to fire.
• If you are on oil: is there oil in the tank? It is the first question for a reason, and a sight gauge that has stuck at a quarter full is very common.

In short — Those five account for a large share of "dead boiler" calls. If all of them check out, it is a fault rather than a setting, and it needs an engineer.

• Write the code down exactly as it appears, along with the make and model from the data badge — that alone often tells James what part to bring.
• Reset once, and once only. If it locks out again, something is genuinely wrong and repeated resets can make it worse.
• In cold weather, look at the condensate pipe — a white plastic pipe leaving the boiler and usually running outside. A frozen condensate is the classic winter lock-out, and gently warming the outside section can revive it.
• Listen for the pump running and feel whether the pipes get warm at all before it cuts out. Heating and then stopping points somewhere different from never firing.

In short — Send the fault code and a photo of the data badge on WhatsApp before ringing — it saves time on the phone and sometimes saves a visit.

• Note how fast it falls: a bar a week, or a bar overnight. The rate narrows the cause down more than anything else.
• Check the outside wall near the boiler for a small pipe dripping when the heating runs — that is the pressure relief valve discharging, and it is a repair rather than a top-up.
• Look under radiator valves and at any visible joints for the tell-tale greenish or white crust that says a slow weep.
• Count how often you have refilled it. Every refill adds fresh oxygenated water, which is what turns a small leak into sludged radiators a few years later.

In short — Do not keep topping it up indefinitely and hope. A failed expansion vessel is an hour's work; a buried leak needs finding before it finds your ceiling.

• Cold at the bottom and warm at the top is almost always sludge, not air. Bleeding will not fix it.
• Cold at the top and warm at the bottom is air, and bleeding it usually will fix it — check the system pressure afterwards.
• One radiator cold while the rest are hot: check both valves are open, including the lockshield under the plastic cap, and that a thermostatic head has not seized shut. Tapping a stuck TRV pin gently sometimes frees it.
• All the upstairs radiators cold: suspect the pump, a zone valve, or a system that needs balancing rather than the boiler.

In short — Sludge is a system problem, so the fix is a clean and a magnetic filter rather than a new radiator — otherwise the same thing happens again.

• Check the tank level properly, and check for water in the bottom of the tank if it has not been drained in years.
• Look at the fire valve — a fusible-link safety valve on the oil line near the boiler. If it has tripped, it needs an engineer, not resetting and forgetting.
• Listen: motor running with no ignition usually means nozzle, electrodes or pump. No motor at all points at power, the control box or a lock-out reset.
• Soot smells or black staining around the case mean it is burning badly. Turn it off and ring rather than running it "until someone can come".

In short — Oil work needs OFTEC registration — JET Heating holds it, which is the reason a lot of the villages off the mains gas grid ring here.