Commission, service and fault-find with confidence.
Pressure, leak, airflow, current and temperature checks for heating, refrigeration and air con. Tap a problem to jump to it.
Smell of gas
Why it happens
Loose fittings, damaged pipework or faulty appliances.
How to tell it apart
A detector helps you pinpoint small leaks at joints during service work. It does not replace the emergency procedure if you can smell gas.
How to test
- If you smell gas, follow the emergency steps first (see What next).
- For service checks, let the detector warm up and zero in clean air.
- Move the probe slowly along joints and fittings and watch for the reading to rise.
A combustible gas detector such as the Benetech GM8800 or FNIRSI GD-02 helps pinpoint a leak.
What next
If you suspect a gas leak, HSE advises calling the Gas Emergency number 0800 111 999, opening doors and windows, and shutting off the gas at the meter if you know where it is. Don't operate switches or use flames (HSE domestic gas FAQs; National Gas emergency contacts). Work on gas appliances must be done by a Gas Safe registered engineer.
Common mistakes
Using a detector instead of calling the emergency line; not zeroing the detector in clean air.
AC not cooling: pressures and temperatures
Why it happens
Undercharge, overcharge, restrictions and non-condensables all show up as abnormal pressures and temperatures.
How to tell it apart
Read pressures together with line temperatures (superheat and subcooling), not on their own.
How to test
- Check hoses and seals; set the gauge to the correct refrigerant.
- Connect to the service ports with the system running at steady state.
- Read pressures and line temperatures and compare with the equipment maker's data.
A digital manifold such as the DY517 shows pressure and saturation temperature.
What next
Target values depend on the system and are given by its manufacturer, so use their data. Handling refrigerant requires F-gas certification.
Common mistakes
Wrong refrigerant setting; reading before the system has stabilised.
Instrument for this step
DY517 Digital Refrigerant Manifold Gauge, 89 Built-in Refrigerants£67.99
Weak airflow
Why it happens
Dirty filters, blocked coils, failing fans or poorly balanced ductwork.
How to tell it apart
Compare air speed at each grille: one low grille points to that duct; all low points to the fan or filter.
How to test
- Measure air speed across the grille face at several points.
- Average the readings.
- Compare with commissioning records or the design figures.
A vane anemometer such as the BT-846A measures air speed.
What next
Clean filters and coils, then re-measure.
Common mistakes
A single reading at the centre of the grille.
Electrical faults at the unit
Why it happens
Worn bearings, failing capacitors and overcharge all raise running current.
How to tell it apart
Compare the current with the rating plate; high current with normal pressures points to the motor or capacitor.
How to test
- Clamp around one conductor only.
- Measure running current at steady state.
- Compare with the rating plate.
A clamp meter such as the ZT-QS7 reads current without breaking the circuit.
What next
Investigate anything above the rating plate value. Electrical repairs should be made by a competent person.
Common mistakes
Clamping around the whole cable.
Instrument for this step
ZT-QS7 Milliamp Clamp Meter AC/DC, Mini DC Clamp Meter, 600V£40.99
Cold radiators and blocked pipes
Why it happens
Air, sludge or failed valves stop flow.
How to tell it apart
A radiator cold at the top usually has air; cold at the bottom often means sludge.
How to test
- Run the heating until it is up to temperature.
- Scan radiators and pipework with a thermal imager.
- Compare flow and return temperatures.
A thermal imaging multimeter such as the ZT-R01 shows the pattern.
What next
Bleed, flush or replace the valve, then re-scan.
Common mistakes
Scanning before the system is warm.
Instrument for this step
ZT-R01 Thermal Imaging Multimeter, 32x32 IR Thermal Camera & 25000 Count Digital Multimeter£113.99
FAQs
Can a gas detector replace a CO alarm?
No. A combustible gas detector does not detect carbon monoxide. Fit a CO alarm.
What pressures should I see?
That depends on the refrigerant and the system. Use the manufacturer's data.
Can I get a VAT invoice?
Yes. All prices include VAT and VAT invoices are available.
Need help choosing?
Contact us and tell us what you need to measure.