How to Check for a Gas Leak

Introduction

If you suspect a gas leak in your home’s piping system or if you are a trade professional whose gauge has detected a leak during a pressure test on a newly installed gas piping system, a pipe leak detector provides a fast and efficient methods to locate the leak.

When Should You Check for Pipe Leaks?

If you detect a lingering sulphur or rotten egg smell in your home, which may indicate a gas leak.

After any DIY alteration of gas pipework or the replacement of a gas appliance, such as a gas water heater.

If an inspection or pressure test is required for permitting following your gas piping installation, it is advisable to check for leaks before engaging a Licensed Gas Service Worker (LGSW) to certify the gas work as safe. Identifying and addressing leaks beforehand can prevent failing the certification test, saving both time and money.

If a pressure test using a gauge detects a leak in a new gas piping installation.

If you are a homeowner undertaking a DIY gas installation or repair, using a leak detector, such as a soap solution, is a practical way to verify the quality of your work. Be sure to apply it after completing any DIY gas piping project.

Method 1: Soap solution

Step 1: Apply Soap Solution to Pipe Joints

Apply the soap solution directly to the pipe joint, solder joint, valve stem, or any other component being inspected. Use a dauber or sprayer to apply the solution directly from its container. If using a dauber, ensure it remains clean and free of debris. If using a spray, and the nozzle becomes clogged, remove and rinse it with warm water. Do not dilute the solution.

Step 2: Observe for Bubbles

After application, wait a few minutes and inspect the area. If small bubbles form around the joint, a leak is present. Carefully examine all joints, fittings, gaskets, flanges, seams, and corroded surfaces that may have perforations. Minor leaks may take over a minute to produce visible bubble clusters.

Step 3: Repeat the Application

For thorough detection, reapply the soap solution if necessary. Rewetting the area can help ensure no leaks are overlooked.

Step 4: Clean Off Residue

After completing the inspection, remove any excess solution with a water spray or a damp cloth to prevent residue build-up on pipes and fittings.

Method 2 : U-Gauge Testing

Fill the U-gauge with an appropriate fluid up to the zero mark and connect it to the gas pipe system near the riser by the meter. If no connection point is available, use the fitting at the cooker hob or gas water heater.
Isolate the system by closing the relevant valves.
Apply pressure to the system (300mm water gauge, 150mm down and 150mm up) and monitor the U-gauge reading for five minutes.
Observe for any slight pressure drops that indicate leaks. If leaks are detected, locate and repair them.
Once the pressure stabilises, record the final reading and release pressure following safety procedures.
The LGSW will issue a certificate similar to City Energy’s Letter of Commissioning (Form DR 10).
If the gas appliance cannot be certified as safe for use, the LGSW shall inform the customer that it is an offence to operate an uncertified gas appliance and advise on the necessary corrective action.

Method 3 : Using the Honeywell BW™ Max XT II

1. Prepare the Detector

Power On & Check Battery: Ensure the device is charged or has fresh batteries. Turn it on and verify it completes a self-test.

Bump Test: Use a certified gas test to confirm sensors (especially LEL for combustibles) respond correctly. Calibrate if necessary.

2. Configure for Target Gas

Select the LEL (Lower Explosive Limit) sensor for combustible gases (Town Gas). Adjust settings for CO.

Note: Methane rises (check high)

3. Inspect Gas Connections & Pipes

With the gas supply on, slowly move the detector’s probe around:
- Joints, valves, flex lines, and the new water heater’s connections.
- Follow the pipework, checking for 10–20 seconds per spot.

Keep the detector close to potential leak points (e.g., threaded fittings).

4. Interpret Readings

Audible/Visual Alarms: Immediate indication of gas presence.

Concentration Levels: Even low readings (e.g., >5 PPM) suggest a leak.

If a leak is suspected, use a soap solution on connections to pinpoint bubbles.

5. Post-Check Actions

Leak Found: Turn off gas immediately, ventilate the area, and repair or contact a professional.

No Leak: Ventilate the area briefly, document the inspection, and power off the detector.

Safety Notes:

Avoid open flames/sparks during testing.
For large leaks, evacuate and call emergency services.
Regular detector maintenance (calibration/bump tests) ensures reliability.

By following these steps, you ensure thorough and safe detection of gas leaks after installation.

Safety Reminder for Gas Appliance Replacements

Any replacement of a gas appliance, such as a gas water heater, must be carried out in compliance with Regulations 20 and 21 of the Gas Supply Regulations. The LGSW must test the gas appliance and its connection to the gas installation, as well as all affected joints, to confirm the system’s safety before use.

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