The simple checks are to make the area safe, read the pressure gauge, look for obvious drips, and confirm power and thermostat settings. These steps take minutes and often restore heat without tools. Keep children and pets away from wet floors while you check. Have a torch and a towel ready so you can see joints and catch small leaks. With basics set, start with pressure and shut-off safety.

Is it safe to leave the boiler on if it is leaking?

It is not safe to leave a boiler on if water is dripping onto electrics, pooling near the unit, or spraying from a joint. Switch the spur switch off and isolate the boiler if you see live parts or smell burning. Put a tray under slow weeps and keep the area dry while you assess. Ventilate the room and keep the flue clear of objects. Once safe, check the pressure because many faults start there.

What boiler pressure should you see on the gauge?

You should see around 1.0 to 1.5 bar when the system is cold and a little higher when hot. A gauge near zero means the system needs repressurising. A gauge over 3 bar suggests an over-pressure problem that may open the PRV and cause a drip. Note the reading before you touch the filling loop. If pressure is low, a careful top-up can help.

How do you repressurise a combi or system boiler safely?

You repressurise by connecting or opening the filling loop and letting mains water in until the gauge reaches about 1.2 bar. Turn the valves slowly and watch the needle rise in small steps. Close both valves fully and check for hissing or drips at the loop. Wipe joints dry so new leaks are easy to spot. With pressure restored, air in the radiators is the next common issue.

Should you bleed radiators if rooms stay cold?

You should bleed radiators if the tops are cold while the bottoms are warm, as trapped air blocks heat. Turn the heating off, use a key at the bleed valve, and let air hiss out until a steady trickle of water appears. Catch drips with a cloth and close the valve gently. Top up the boiler pressure again if the gauge drops after bleeding. If radiators still stay cold, controls may be the cause.

Are your thermostat and programmer set correctly?

They might not be, so check that the programmer is on “heating,” the room thermostat is above room temperature, and batteries are fresh. Make sure the boiler spur switch is on and the fuse is intact. Confirm the system clock and schedules are correct after a power cut. Try a simple override to force heat for a short test. If settings are fine, look for specific leak points.

Where do small boiler leaks usually come from?

Small leaks often come from the filling loop connections, pump seals, auto air vent, or compression joints on nearby pipework. A constant drip from the PRV pipe outside suggests high pressure or a faulty valve. A wet case seam may mean a condensate issue on a condensing boiler. Dry each area and watch for a new bead of water to find the source. When leaks start in cold weather, the condensate pipe is a suspect.

Could a frozen condensate pipe be stopping the boiler?

Yes, a frozen condensate pipe can lock out a condensing boiler and stop heating. You can thaw it by pouring warm (not boiling) water along the outside pipe and lagging it after it clears. Check the trap and reconnects are secure before a reset. Press the boiler reset once and give it a minute to start. If it locks again, move to simple resets and power checks.

Should you try a boiler reset and basic power check?

You should try one reset after checking pressure, bleeding, and condensate, as the control board may clear a minor fault. Make sure the spur switch is on and the breaker or RCD has not tripped. Listen for the pump and fan on start-up and note any fault codes on the display. Write the code down for later if it returns. If a leak continues, reduce water flow to the boiler.

Can you turn off the water to the boiler without shutting off the whole house?

Yes, you can often close the cold feed isolation valve to the boiler to slow a leak while keeping cold taps alive. Turn the small inline valve a quarter turn so the slot sits across the pipe. Do not force tight valves and do not cap safety pipes. Place a tray under the boiler to catch drips and protect the floor. If water still finds a way out, call for help and keep drying.

What should you do if the pressure relief valve keeps dripping?

You should stop topping up and let the system cool because constant filling can push water out of the PRV. Check that the pressure is not above 1.5 bar when cold after a rest. A faulty expansion vessel or debris in the PRV may be the root cause. Note the drip rate and the pressure reading for the engineer. Until then, keep an eye on the outside discharge pipe.

Why are radiators still cold when the boiler runs?

Radiators can stay cold if the pump is stuck, the diverter valve is jammed, or TRVs are turned down. Turn each TRV to five and check the lockshield has not been closed after decorating. Feel the pipes to see where the heat stops and note which rooms fail. Try one room with other rads turned down to test the flow. If the flow is weak across the home, a proper diagnosis is due.

When should you isolate gas or electricity and stop DIY?

You should isolate gas or electricity and stop DIY if you smell gas, see scorch marks, hear arcing, or water hits live parts. Turn off the spur switch and step away from the boiler if safety is in doubt. Keep windows open and do not use naked flames. Safety beats speed at every stage. Once safe, a clear call visits quickly.

What information helps when you book an emergency visit?

Useful information includes the boiler make and model, pressure reading, fault code, where the leak shows, and what you have tried. Share parking and access details so the arrival is smooth. Tell them if anyone vulnerable lives in the property. Keep your phone on and the area clear around the boiler. After the fix, a few habits prevent repeat faults, and knowing the basics of handling a burst pipe can make the next call-out much easier.

What simple steps prevent future leaks and no-heat problems?

Simple steps include yearly servicing, cleaning the magnetic filter, and keeping pressure between 1.0 and 1.5 bar. Add inhibitor, bleed rads each autumn, and lag condensate and loft pipes. Exercise isolation valves twice a year so they turn when needed. Keep the flue clear and the boiler area tidy for airflow. With routine in place, and support from boiler repair specialists, you are ready to wrap up.

What is the calm, safe plan when a boiler leaks or will not heat?

The calm, safe plan is to make the area safe, check pressure, bleed air, confirm controls, and thaw a frozen condensate if needed. Use the filling loop with care, reset once, and note any fault codes or steady drips. Isolate the cold feed to the boiler if a leak continues, and keep trays and towels in place. Call for help with clear details so the repair is fast and accurate. With simple checks and steady steps, you limit damage, restore heat, and keep your home safe.