Diagnosing Voltage in the HVAC Industry: Why Digital Multimeters Are Essential  

The role of an engineer in the HVAC industry can consist of many roles and locating low-voltage short circuits is among these roles.

Experienced engineers may be able to spot some defects from sight, but when looking to keep productivity at its best, an engineer will want to ensure that they’re keeping momentum without overlooking a series of issues.

Despite engineers being experienced in the field, more and more are finding that modern-day measures are helping ensure installs and repairs are safe, while saving time for the engineer.

The use of the right tools also ensures that the customer is confident that any voltage issues will be rectified without issue.

When searching for a digital multimeter online there will be a vast amount of options available, but there are factors that need to be considered before purchasing a digital multimeter.

The right type of digital multimeter can ensure that all elements of an HVAC repair are taken care of, and a professional digital multimeter will make light work of elimination hinderance such as phantom voltage.

Purchasing the Right Type of Digital Multimeter

Given the amount of choice available it would be easy to assume that any digital multimeter is suitable.

Although this is kind of true, engineers will find that they normally carry three to four multimeters to ensure they’re covering all bases.

A digital multimeter designed for the HVAC industry will allow an engineer to carry out a series of toles with one tool, and it also ensures that the engineer has access to a device that also provides an overview of the temperature.

Although some models will vary, digital multimeters designed for the HVAC industry will often come with the following features:

Capacitor Test: When searching for voltage issues, one of the most common problems engineers face in relation to the hard-start capacitor.

As such, it’s vital that engineers establish that this feature is present on the digital multimeter the purchase.

Voltage Meter: A digital multimeter for HVAC engineers needs to be able to measure a DC voltage of 300V and AC voltage of 600V.

Continuity Meter: Continuity is needed to ascertain whether a circuit is open. This is a commonplace feature on digital multimeters and will often give a clear indication when a test has been completed.

Ampere Meter: An ampere meter needs to read at least 1/100 ampere of the current, as this will allow an engineer to adjust the flow of current travelling to the HVAC system accurately.

This is only an overview of the features available with digital multimeters, and when browsing what’s available engineers may find that some devices hold more benefit than others when it comes to their role.

Should Old Digital Multimeters Be Upgraded

Engineers that have been using a digital multimeter for some time may find that the one they currently have is more than capable of locating voltage defects.

In some instances, the engineer may find that there is some confusion with leads and markings when using older models, and there could even be times where the multimeter is too old to contend with modern-day applications.

If this is the case, then updating your current digital multimeter can be worth considering.

How Do Digital Multimeters Compare to Analog Multimeters?

Before the introduction of digital multimeters, engineers would use analogue multimeters. Although still available today, the use of analogue multimeters has lost traction since the introduction of its digital counterpart.

On the upside, an analogue is a very affordable option for those who are only dealing with a couple of jobs. But as a workload increases, engineers can find that the use of an analogue multimeter n

Some of this can be attributed to how difficult they can be to use the first time, whereas some engineers feel that the readings they’re getting aren’t all that accurate.

Some can also find that analogue multimeters can display low resistance or high sensitivity, which means the readings received aren’t always right.

As a digital multimeter displays digits on an LCD or LED screen and will provide more accurate reasons as a result. What’s more, a professional digital multimeter will have more resistance than that of an analogue multimeter.

What Type of Digital Multimeter Should an Engineer Purchase?

When searching for a digital multimeter, there will often be a lot of choices available. This process can be made more overwhelming if you’re not sure what features you should be concentrating out.

Those updating their old equipment will need to ensure that the multimeter purchase is able to contend with tasks that the old multimeter wasn’t up to.

This isn’t the only reasons why a digital multimeter is replaced, as some may just want to update their current equipment to something, they’re more familiar.

Whatever the reasons for updating or purchasing a digital multimeter for use in the HVAC industry, it’s important that you carry out some research to ensure that the device you buy is beneficial to you and your workload.

What is the Problem with Cheap Digital Multimeters?

When purchasing a digital multimeter, engineers are often told to avoid cheaper iterations, but why is this.

To say that all cheap digital multimeters are inferior is unfair, but the cheaper versions of digital multimeters aren’t really designed for professional.

Cheap digital multimeters have their place, but they’re often only suitable for scenarios that are few and far between.

This isn’t to say that a professional digital multimeter should cost a fortune, but it’s vital that engineers ensure that the device they’re using is designed for HVAC professionals.

Many cheaper digital multimeters will have been tested, whereas others may have not. Simply purchasing a digital multimeter based on the price could have consequences later on, so research is essential.

Buying Digital Multimeters from the Right Supplier

The price you pay for a digital multimeter will depend on the functionality it offers.

Some engineers may only have a small budget put aside when it comes to purchasing new tools, so want to ensure that the investment they make is the right one.

To ensure that you’re buying a reputable and reliable digital multimeter, engineers first must find a supplier that can be relied on.

HVACTOOLS has been a supplier of a series of tools for the HVAC industry for several years and ensures that all its products have been put through rigorous checks before being sold.

As well as serving the HVAC industry with tools, it can also a vast choice of digital multimeters, which include but aren’t limited to the following:

400A True RMS Digital Clamp Meter

As the name implies, the RMS Digital Clamp Meter offers a clamp functionality and meets CAT III safety standards.

The main features of the 400A True RMS Digital Clamp Meter are as follows:

  • K-Type Temperature Probe
  • Auto-Range
  • Data Hold
  • True RMS
  • K-Type Temperature Probe
  • 30mm Large Jaw
  • Auto Power Off

This digital multimeter is available in red or grey, measures in at 220 mm x 75 mm x 40 mm and comes complete with test lead, batteries and contract temperature probe.

UNIT-T Standard Digital Multimeter

Even though engineers may have a limited budget, this doesn’t mean that they should have to use a digital multimeter that’s not up to the job.

The UNI-T Standard Digital Multimeter is a prime example of how professional and reliable a digital multimeter can be at a low price point.

The following features are included with the UNIT-T Standard Digital Multimeter:

  • Data Hold
  • Low Battery Indicator
  • Sleep Mode
  • Manual Ranging
  • Continuity Test – With Buzzer
  • Diode Test
  • Capacitance

The multimeter comes complete with batteries, test leads, a temperature probe and a rubber carry case.

Other Factors to Consider

When purchasing a digital multimeter from a professional supplier, an engineer will often be given everything they’re needed to get started within the box, but there may be some accessories that need to be purchased depending on the type of applications you’re dealing with.

Many digital multimeters will be suitable for several engineers, but there may be instances where accessories need to be purchased to achieve the full benefit of the meter.

For example, some may be fine just carrying out checks using probes, whereas others will need access to crocodile clips.

In some instances, engineers will just want to ensure that they’re protecting their investment, so may want to purchase a protective case if one wasn’t provided.

Frequently Asked Question Relating to Digital Multimeters

Depending on your experience with digital multimeters there can be other questions raised by HAVC engineers searching for a digital multimeter.

When shorting test leads together in resistance mode, the multimeter doesn’t show zero. Why is this?

Although many engineers expect to see a zero when shorting their test leads together, this can lead some digital multimeters measuring the resistance of the lead. For new leads, this is anything from 0.1 to 0.3-ohm range.

What difference is there between the Min/Max and Peak modes?

The Min/Max mode shows the highest and lowest readings that the meter took when recording mode was started.

To obtain an accurate reading, the measured signal needs to be 200 milliseconds or longer.

The Peak Mode measures the positive and negative peak and works with peaks of 250 microseconds and above.

Using a Digital Multimeter: Some Do’s and Don’ts

Although the safety aspects of using a digital multimeter are straightforward, they can be easy to overlook, especially if an engineer is using a digital multimeter for the first time.

The following is an overview of some do’s and don’ts that ensure your equipment remains in working order, and no danger arises when working at a customer’s property.

DO Double-Check the Ports

There’s nothing worse than a digital multimeter not showing a reading but a few simple checks will often have you and running in no time.

For example, should the probes be plugged into the wrong ports, then this will cause an issue. Double-checking the ports have been connected in the right way means less frustration when out in the field.

DO Pay Attention to Manuals

Engineers that have been working in the HVAC industry for several years will know how a digital multimeter works, but newer iterations may have features that seasoned engineers aren’t familiar with.

Dismissing the manual could mean that you’re left bewildered if you need to use the said feature during a repair or install.

Even if you don’t read the manual straight away, it could be a good idea to have it close to hand so there are no hindrances in relation to productivity.

DON’T Pierce Jackets to Test Wiring

For the most part, an engineer will be in little doubt as to what not to do with a digital multimeter, as much of the process relies on common sense.

However, those new to the industry may be carrying out work that could cause problems later on without even realising.

One of the most common mistakes made by new engineers is piercing the jacket surrounding wires to carry out a test.

While it’s understandable why this is done, it does mean that there is potential for containments to find their way into the wiring.

This could cause a series of problems later, even leading to corrosion of the wires.


Everyone will have their own requirements when it comes to purchasing a digital multimeter, which again reinforces the importance of using the right supplier.

Using a supplier such as HVACTOOLS not only ensures that the digital multimeter you purchase is safeguarded with a 12-month warranty but also gives engineers and businesses a wealth of choice in relation to all HVAC tools and devices.


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