Testo 558s Smart Vacuum Kit – Touchscreen 4-Way Digital Manifold + 2× 115i Clamp Thermometers + 552i Vacuum Probe (0564 5582)

The testo 558s Smart Vacuum Kit is a kit designed to carry out commissioning, evacuation and troubleshooting work on refrigeration and air conditioning systems and heat pumps from a single instrument. At its heart is a 4-way digital manifold with a touchscreen; the connection to the measuring probes is wireless (Bluetooth), so no cable runs between the manifold and the probes.

The kit covers three measurements of everyday service work at once: pressure is read from the manifold itself, line temperatures from two clamp thermometers, and the vacuum level from a separate vacuum probe. Superheat and subcooling values are calculated automatically by the instrument.

What Is in the Kit?

• 1 × testo 558s — digital manifold with 4-way valve block, capacitive color touchscreen
• 2 × testo 115i — wireless clamp thermometers (one on the suction line, one on the liquid line)
• 1 × testo 552i — wireless vacuum probe, with calibration protocol
• Carrying case
• USB-C charging cable and spare 3 × AA alkaline batteries
• Calibration protocol and user manual
• testo Smart App — free, iOS and Android

Not Included in the Kit

To avoid false expectations, we state clearly — the following are not included in this kit:

• Charging and vacuum hoses. The version with hoses is sold under a separate order number.
• Vacuum pump.
• Digital refrigerant scale (testo 560i) and Smart Valve — required for the automatic charging function.
• Clamp meter (testo 770-3) and magnetic hanging strap.

Why Measure the Vacuum?

Saying "it has pulled enough" based on the vacuum pump's running time is one of the most expensive habits in the field. Moisture remaining in the system reacts with the refrigerant and oil during operation to form acid; it causes icing in the capillary tube and expansion valve and, over time, failure of the compressor winding.

The manifold's pressure display cannot do this job — the micron range is a separate measurement. The manufacturer's own user manual states this clearly: the use of the 552i probe is recommended for vacuum measurement; although measurement with the manifold without the probe is possible, it is not recommended due to insufficient accuracy. This is exactly the difference between this kit and the manifold sold on its own.

Four Values on the Display at Once

In vacuum mode the 558s simultaneously shows: the current vacuum value, the ambient temperature, the evaporation temperature of water at that vacuum and the difference between the two. If the difference has not opened up enough, the water in the system is not boiling at that vacuum; the technician makes the "let me pull a bit longer" decision from the display, not by guesswork.

A vacuum target and a maximum rise target can be set on the instrument; the manufacturer's defaults are 500 microns and 1,000 microns.

Moisture or Leak?

Once the target has been reached, the pump is isolated with the valve and the behavior of the vacuum is monitored:

• If the value stays constant, the system is dry and leak-tight — the vacuum is complete.
• If the value rises and levels off at a certain point, there is moisture inside; the water has evaporated and settled at its equilibrium pressure. Evacuation is continued.
• If the value keeps climbing, air is entering from outside, meaning there is a leak; pulling a vacuum will not help, the leak must be found first.

For leaks, the instrument also has a temperature-compensated pressure tightness test: pressure and ambient temperature are measured together, pressure fluctuations caused by temperature are filtered out and the real drop is shown.

Tasks Carried Out on the Instrument

• Superheat / subcooling — the two 115i probes are clamped onto the suction and liquid lines, and the values are calculated in real time.
• Evacuation — micron tracking with the 552i.
• Pressure tightness test — temperature-compensated.
• Target superheat and Delta T.
• Compressor test — via the discharge line temperature.
• Refrigerant charging — automatic/target-weight charging additionally requires the testo 560i digital scale and the Smart Valve.

More than 90 refrigerants are stored in the instrument (R32, R290, R410A, R404A, R134a, R454B, R513A, R600a, R744, R1234yf and others); frequently used ones can be saved as favorites. It is compatible with A2L and A3 class flammable refrigerants. The refrigerant list and software are updated via the app (OTA).

🚨 Ammonia (R717) and refrigerants containing ammonia cannot be measured with this instrument. It cannot be used in industrial ammonia plants.

Display, Power Supply and Logging

• Capacitive touch color display; when working with gloves, the keypad can also be used. As a third option, full operation is also possible from the testo Smart App.
• A 30-minute trend graph is shown on the display; it makes it possible to catch anomalies without looking at the instantaneous value.
• Hybrid power supply: internal 3,400 mAh 18650 Li-Ion (charging via USB-C, 80% charge in 1.5 hours) or 3 × AA alkaline. Battery life is over 70 hours with illumination and Bluetooth on, and up to 190 hours with only the display on.
• 🪤 Below −16 °C the internal battery switches off; if you will be working outdoors in winter conditions, AA batteries must be fitted.
• Long-term data logging (1–72 hours) is supported; this function is activated by purchasing it separately in the app and is not included in the kit.
• Up to 4 wireless probes can be connected at the same time.
• IP54 protection class.

testo 558s — Technical Specifications

testo 552i — Wireless Vacuum Probe

testo 115i — Wireless Clamp Thermometer (2 units)

Differences Between the 550s, 557s and 558s

None of the three models can measure ammonia, and evacuation is monitored with the 552i probe.

App Requirements

The testo Smart App requires a Bluetooth-enabled phone/tablet with iOS 13.0 or Android 8.0 or later. The app is free. The manifold also works on its own without the app; the app is used for reporting, archiving and extended display. Measurements are exported as PDF and CSV, and photos and notes can be added to the report and sent by e-mail on site.

Introduction and Application Videos

Evacuation with Testo digital manifolds (Turkish)

testo 558s introduction (English)

Tightness test on a refrigeration system (English)