How To Test Your Furnace’s Ignition Control Module

What is an Ignition Control Module?

The Ignition Control Module (ICM) is a part of your furnace with one primary function: to light the burners. It receives a signal from the thermostat to start. It sparks (direct spark ignition) and sends power to the gas valve. It shuts down if the Ignition Control Module sensor doesn’t recognize a flame within a few seconds.

Unlike a fan board or full control circuit board, an ignition control module does not control the blower. It only controls lighting the burners. Because it uses an electronically-controlled ignition to light the burners, it is more energy efficient, generally safer, and more reliable than the standing pilot light found in most older gas furnace models.

However, ignition control modules can still encounter problems. Electronic ignition failure is quite common and can prevent your furnace from turning on.

Some furnaces utilize Intermittent Pilot (IP) systems, where the pilot only ignites the burner gas when the thermostat demands heat. Others use Hot Surface Ignitors (HSI), where electricity passes through a filament and heats up, eventually igniting the gas for the burner.

Could My Furnace Ignitor Be Bad?

Several things can happen when you have a faulty furnace ignition control module, but the obvious symptom is usually no heat. This is because heating doesn’t happen without furnace ignition. The ignitor must light the burners to produce warm air.

There may still be air coming out of the ducts; it just won’t be warm. This can be due to the circulator blower running as a safety measure when the furnace fails to light properly.

With an intermittent pilot system, your ignition may not spark at all, or the spark happens but does not light the pilot. Sometimes, the pilot will light, but the gas valve may not open, and the burner will not light. HSIs can also malfunction over time due to normal wear, damage due to improper handling, or a too-high electrical current in your home. Your furnace may start short cycling as the igniter attempts to light the furnace again and again. You may also notice the ignitor isn’t glowing red.

Troubleshooting Your Ignition Control Module

Many things can happen during the ignition process that can cause the system to fail. From failure to light the pilot to faulty sensors, any issue will signal to the circuit board that it isn’t safe to start the furnace. A few simple ways to investigate are:

  • Turn the furnace off, then wait a few minutes before turning it back on to see if the issue is resolved.
  • Check your furnace filter. A dirty filter can cause your furnace ignition to cycle on and off repeatedly, leading to malfunction.
  • Dirty filters, clogged ductwork, or plugged flue can cause limit switches to open when excessive heat buildup occurs.
  • Look at the ignition cable to ensure that there are no cracks or breaks and the connections are clean and secure.

How to Test for Basic Ignition Issues in the Furnace

To test your furnace’s ability to ignite, you’ll need a multimeter, but first, you must be sure you are taking all safety precautions.

  • Turn off all power to the furnace and close off the gas. Allow your furnace to cool before attempting any testing.
  • Remove the panel door and locate the Ignition Control Module (usually positioned near the gas port). If you see visible damage, then it needs to be replaced. If not, detach the wires, loosen the screw, and remove the Ignition Control Module from its socket.
  • To check if the ignition module is getting voltage, set the multimeter to AC voltage (VAC) reading and check for voltage at the thermostat input or 24VAC input to the Ignition Control Module. You should get a reading of 24VAC with respect to common or ground. If the multimeter stays at zero, a technician may be needed to troubleshoot the furnace for loss of power.
  • To check for ignitor resistance, set the multimeter to resistance readings (ohms). Remove the igniter from the circuit, connect the meter probes to the ignitor, and check the reading. A correctly functioning ignitor will give a resistance value between 40 – 200 ohms. If your ignitor has lower resistance, it’s probably ready to be replaced.

Replacement Ignition Control Modules

ICM Controls manufactures top-quality, cost-effective ignition control modules for gas and oil boilers, furnaces, and other heating appliances. Visit ICM’s website to cross-reference the part you need if you’re comfortable installing it yourself. If not, call an HVAC expert in your area.

surge protection for ev

Surge Protection for EV Charging

Low transient voltages

Transient Voltages at Low Levels: Why Should You Care?

protect devices from low transient voltages

What are Transients?

Known more familiarly as power spikes or surges, transient voltages are momentary changes in voltage or current that occur over a short period of time, usually lasting only fractions of a second.  But these “blips” can have a big impact.  In fact, transient activity is believed to account for around 80-percent of all electrically-related downtime. Transients can be oscillatory, where there are voltage swings above and below the normal line voltage, or impulse transients, where there’s one quick pulse above the normal line voltage—such as the case with a lightning strike.

Lightning is the transient source people usually think of first. Transients caused by lightning are seldom a direct hit, but rather a lightning strike near a power line that creates discharge. Normal utility operations can create transients as well during the switching of facility loads or capacitor banks, tap changing on transformers, poor or loose connections, high winds, even static electricity in very dry climates.

Transients can even be generated by the powering off and on of equipment in your home or business–photocopiers, laser printers, compressors, generators, and other motors, overloading a circuit, and defective wiring.

While high-intensity power surges are rare, most heavy-duty appliances like refrigerators and air conditioners create low-level surges every day. Although the damage may not be immediate, over time these minor surges can impact the general functionality, performance, and lifespan of that electrical equipment.

Read More: Power System Transient Studies using EMTP-RV

Why do we need protection from transients? 

The problem with transients is that they can negatively impact any connected electrical equipment and ultimately cause them to fail or work improperly.  Motors run hot, fail prematurely, and produce additional transients in the process.  Light bulbs run hotter, less efficiently, and fail early.  Black rings at the end of fluorescent tubes are a clear sign of transient activity. While replacing light bulbs may not seem like a major expense or inconvenience, replacing your HVAC system or new pool system certainly are.

For this reason, electricians recommend including surge protection as part of any HVAC or pool/spa installation along with a whole house surge protector.

Also Read: Prepare For Power Surges Says Electricity Providers

What is the potential benefit of a properly selected and installed SPD?

Don’t let transient power spikes get the best of you and cost you thousands of dollars. Today’s surge protectors can mitigate both high-amplitude transient voltages and the ever present low-level transient voltages. The most effective solution is a whole house surge protector that protects the circuits directly at the electrical panel. A whole house surge protector will help protect your electronics from internal and external power surges and can double or triple the life of electrical and electronic equipment.

Protecting your entire home with a properly installed surge protection device can:

  • Prevent damage to your electronic devices
  • Prevent high-intensity power surges which can cause destructive fires by regulating the passage of surplus voltage
  • Protect devices from the internal power surges which happen daily, prolonging their lifespan
  • Save you the cost of replacing expensive equipment that becomes damaged by transients. Whole house surge protectors are a cost-effective solution.

No matter how good, surge protectors don’t last forever, particularly with high surge activity, and may need to be replaced periodically. Look for a protector that has some way of alerting you that it has failed (usually referred to as “fault identification”), such as an indicator light or audible alarm, and is no longer protecting the connected equipment. When this happens, the protector should be replaced.

defrost control boards

The Do’s & Don’ts Of Defrosting A Commercial Freezer

defrost controls

Today’s modern commercial freezers are designed to save time, money, and generally make life easier because they’re auto-defrosting.  That means there’s no build up of ice to take up valuable storage space, and there’s not the inconvenience of having to relocate perishable inventory while you turn off the freezer and let the ice melt.


Commercial freezers come with a defrost system controlled by a defrost control board that determines when to turn on the heater to melt ice build-up on the evaporator coils.  During a defrost cycle, the coils heat up to melt any accumulated frost or ice.  This allows the evaporator to maintain its optimal heat absorption and cooling functions. But defrost control boards aren’t foolproof. If the control board isn’t functioning correctly, the defrost cycle may not turn on causing frost to build up on the coils and, over time, inside the freezer.

When a defrost control board fails or malfunctions, the board must be replaced. If the ice build up is significant, you may need to manually defrost the freezer. You should plan to defrost when the ice thickness reaches ¼ or ½ inch, if not sooner. Otherwise, your freezer is working harder to cool your food, wasting energy, and increasing your electrical bill in the process. And because ice build-up obstructs air circulation, the temperature of your freezer is less likely to be consistent, which can pose a food safety risk and affect the quality of your inventory.

Read More: The Best Commercial Freezers of 2022


For best results, defrosting requires emptying the contents of your freezer.  This allows for better airflow. Move inventory to another freezer. Then turn off the freezer and leave the door open overnight so the ice can melt and water drain.  To help speed up the process, you can:

  • Place a fan in front of the open freezer door to direct warmer air into the space and speed evaporation of water.
  • Use a wooden or rubber scrapper to remove large chunks of ice but be careful not to scratch or damage the inside of the freezer or its components
  • Place bowls or containers of warm water on the freezer shelves to help ice melt faster
  • Carefully use a blow dryer to remove layers of frost or ice, but be certain to control the temperature and how long you direct heat. You don’t want to damage any gaskets or seals. And don’t stand in puddles while you are using the blow dryer.
  • Place warm/hot towels over areas of ice buildup.
  • Do clean your freezer space before restocking
  • Do ensure your freezer is cold again before putting any food back in it. This could take a few hours once it’s turned back on after defrosting.


  • Don’t leave the freezer turned out
  • Don’t close the freezer door while defrosting
  • Don’t use boiling water
  • Don’t use an ice pick, knife, or sharp utensil to scrape ice. You can easily cut yourself or damage the freezer.
  • Don’t wait until you can’t close the freezer door to finally address the ice buildup. Excessive ice in a refrigerator can drastically limit its effectiveness, making the appliance work harder and increasing its electricity consumption.
  • Don’t forget to wipe down the seals of your unit’s door.

Read More: Commercial Refrigerator and Freezer Market Growth at a Rate of 7.00% by 2029


Before turning your freezer back on, replace the defrost control board.  ICM Controls manufactures top quality, cost-effective defrost controls to control the timing and duration of defrosting, with options to manage temperature, alarms, active or passive cycles. ICM550-ENC is a drag and drop replacement for several different control boards, includes a multi-functional timer, and is available with and without a weatherproof enclosure.

OEM vs. Aftermarket: What’s The Difference?

OEM vs. Aftermarket

Anyone who’s had a car repaired or their HVAC system or a home appliance serviced has probably heard the terms “OEM” and “Aftermarket” in reference to replacement parts. You may not have known what the difference was (besides price) and let your repair person or even insurance company make the final decision about which parts to use. Allow us to unmuddy the waters and give you the facts.

What is OEM?

OEM refers to “Original Equipment Manufacturer,” meaning that the parts are made by the manufacturer who built the equipment that needs the replacement part(s).

For example, if your Rheem gas furnace stops working and needs a new control board, the OEM replacement furnace control board made by Rheem (or their chosen surrogate) can be used to replace the original Rheem control board that came with your furnace when it was initially purchased and installed.

It fits into your furnace model perfectly because it was designed expressly for your Rheem furnace and other Rheem models.

Also Read: Market size of automotive OEM coatings

What is Aftermarket?

Aftermarket parts are made by a third-party company and are most often form, fit, and functional replacements for one specific manufacturer’s part.  Reputable aftermarket manufacturers, like ICM Controls, make replacement parts that are just as good if not identical to the part you need, but they’re not made by the same company that manufactured the original part that came with your equipment (although sometimes they are, more on that shortly).

Some aftermarket manufacturers do make universal parts that are replacement parts for many different manufacturers’ products, but in general, this is done as a convenience to the technicians servicing a variety of brands.

It’s a good idea to understand who is making the aftermarket part you’re purchasing and where it’s being made.  There are less reputable suppliers out there who import low-quality aftermarket parts that don’t perform as intended and can affect the performance or lifespan of the equipment you’re repairing.

Also Read: The Projected size of the U.S. automotive aftermarket between 2020 and 2024

OEM vs. Aftermarket: Difference in Price

OEM parts tend to cost more than Aftermarket parts because they are manufactured to fit the specifications of a specific type of equipment, such as a gas furnace. Aftermarket parts can usually save you a little bit of money because they are designed to fit several different types of equipment and have fewer steps along the supply chain, which helps contain costs.

OEM parts go from the manufacturer to OEM to distributor to dealer to you and get marked up along the way, so everyone makes a profit. Aftermarket parts have fewer intermediaries, which can save you money.

OEM vs. Aftermarket: Differences in Design, Quality & Functionality

OEM parts are exact replacement parts and were specifically designed to duplicate the part used when your equipment was first built. The quality of an OEM part is guaranteed to be the same (or at least strikingly similar) as the part already used on your equipment or vehicle.

Aftermarket parts are often reverse-engineered. Because of this, the quality can vary depending on the manufacturer and country of origin. This may mean the aftermarket part may not function exactly as needed or last as long.

American-made parts are generally regarded to be of better quality.

To complicate things a bit more, it’s important to note that aftermarket parts can be made by the same company that made them for your original piece of equipment.

ICM Controls supplies many OEM parts for an array of OEMs and the aftermarket. At ICM, many OEM and aftermarket parts are one and the same. The branded OEM part is identical to the aftermarket part.

OEM vs. Aftermarket: Warranty & Availability

While replacement parts from various manufacturers have different warranty periods, OEM products tend to have the shortest warranty period – between 30 and 90 days. Aftermarket suppliers are usually more generous with their warranty period, offering up to a year after purchase.

This is not to say that there is an aftermarket replacement part option for every OEM part. In specific industries, like lawncare equipment, OEM parts rule, and there are very few aftermarket parts available.

OEM Parts Aftermarket Parts
Made by the equipment’s manufacturer Made by a third-party company
Good quality Quality can vary by manufacturer and where it’s made
More expensive Less expensive (no middle-man)
Better availability Only certain replacement parts are available
Shorter warranty period Better warranty

Which one should I choose?  OEM or Aftermarket?

The answer is “it depends” and hinges on what part you’re replacing in what kind of a system or equipment. Most maintenance specialists know when an OEM vs. Aftermarket part makes a difference, and they’ll tell you when it matters and when it’s perfectly okay to save some money. Some auto insurance companies only pay for aftermarket parts, but you can always elect to pay the difference if/when you believe the OEM part is the better choice.

Both OEM and aftermarket part manufacturers are regulated and inspected. The only difference is who makes the parts. Some people feel strongly about using OEM parts, particularly if they are repairing a new car or restoring an old one. Some people have no preference whatsoever and are focused on saving money where they can.

The best way to tell a quality aftermarket company from a less reputable one is to take a look at their offerings.  Do their parts come with warranties? Are there installation videos and helpful blogs on their website?

Do they offer technical support and have a customer service help-line that’s based in the US?  Aftermarket companies that look like they care about their parts and customers usually do.

Relevant Products:

Prepare for power surges

Prepare For Power Surges Says Electricity Providers

Prepare for power surges
Among the growing number of consumer and industrial goods now in short supply, electricity will likely join that list alongside baby formula, semiconductor chips, building supplies, water, and aluminum.

As summer heats up and air conditioners work overtime to keep homes and businesses comfortably cool, the U.S. power grid may not have what it takes to keep the lights (and A/C) on for everyone. Rolling brownouts could be in the cards for anyone across the country.

State officials and media outlets warn consumers and businesses alike to plan for longer, more frequent outages.

Beyond the obvious (comfort, productivity, sanity), what else is at risk? Millions of dollars of electronics, appliances, and investments keep our homes and businesses running smoothly.

Read More: Electric Grid Operators Warn Of Potential Summer Blackouts   

What Causes Power Surges in Electronic Systems?

Sudden power surges can happen whenever electricity is cut off and immediately reconnected. When a large-scale power grid failure occurs known as a blackout, the jump of electricity coming back on can force too much current through your electronics, which can damage them, reduce their lifespan, and cause problems with your home or business’s investments.

Brownouts are another common grid-related issue. In a brownout, the voltage provided by the power supply drops below its standard value, but the electric service is not interrupted completely.

Reduced voltage may seem better than having no voltage, but brownouts can be worse than blackouts in many cases. Electrical devices are designed for a specific voltage range and can suffer damage when exposed to a voltage that is too high or too low.

Power grids aside, epic summer thunderstorms with lightning strikes can result in the same damaging effects. Your standard North American electronic devices are rated for 120 volts.

A major lightning strike creates an electromagnetic pulse that can send millions of volts into a building or home’s electrical panel, wiring system, and connected devices, frying them instantly.

Read More: Large Parts Of The U.S Risk Blackouts Due To Heat Extreme Weather 

Installing A Whole-Home Surge Protector

While many people have point-of-use surge protector strips on televisions, computers, and gaming equipment, most people forget about protecting larger appliances like their HVAC system, freezer, pool system, or even their commercial machinery.

The most effective solution is a whole-home surge protector that protects the circuits directly at the electrical panel, modulating and controlling your home’s power. A surge suppressor will help protect your electronics from internal and external power surges.

Don’t let transient power spikes get the best of you. Protect your investments. ICM Controls offers a complete catalog of Surge Protective Devices and Line Voltage Monitoring Relays designed for single and 3-phase applications.

Relevant Products:

Power Surge Protection Devices:

ICM517  –  (Single-Phase 120/240 VAC, Type 2 Surge Protective Device. Max surge current 100,000 amps, NEMA 3R Rated Metal Enclosure)

Whole home:

ICM518  –  (Split/Single-Phase 240 VAC, Type 1 & Type 2 Whole Home Surge Protective Device. Max surge current 100,000 amps, NEMA 4X Rated Enclosure)

ICM530  –  (3-Phase Delta 240V & WYE 120V/208V, Type 1 & Type 2 Surge Protective Device. Max surge: 150,000 amps, NEMA 4X Rated Enclosure)

ICM531  –  (3-Phase Delta 480V Or WYE 277V/480V, Type 1 & Type 2 Surge Protective Device. Max surge: 150,000 amps, NEMA 4X Rated Enclosure)

ICM532  –  (3-Phase Delta 600V Or WYE 346V/600V, Type 1 & Type 2 Surge Protective Device. Max surge: 150,000 amps, NEMA 4X Rated Enclosure)

ICM533  –  (3-Phase Delta High Leg 120V/240V, Type 1 & Type 2 Surge Protective Device. Max surge: 150,000 amps, NEMA 4X Rated Enclosure)

Voltage Monitors:

ICM492  – (Single-Phase 90/240 VAC, Line Phase Monitor, LCD Display, 5-fault memory diagnostics fault identification)

ICM450A (3-Phase Line Phase Monitor, LCD Display, 25-fault memory diagnostics fault identification)

ICM450A+ PLUS (3-Phase Line Phase Monitor, LCD Display, 25-fault memory diagnostics fault identification, and Modbus communication)

Combination Voltage Monitor / Surge Protection:

ICM493  –  (Single-Phase 200/240 VAC, Line Phase Monitor w/ built-in Surge Protection, NEMA 3R Rated Metal Enclosure)

ICM launches comprehensive line-up of surge protective devices

Offering Multiple Configurations in Single and Three-Phase Protectors

November 8, 2021 – Syracuse, New York – Expanding on the success of its best-selling ICM517 Single Phase Surge Protector and its extensive Line Voltage Monitor offerings, ICM Controls recently launched a new, comprehensive lineup of Surge Protective Devices in multiple configurations, designed with the HVAC/R, Appliance, Electrical, and Pool & Spa markets in mind.


Proudly made in America, the expanded lineup includes an additional single-phase option (ICM518) along with four different configurations of a three-phase SPD’s (ICM530, ICM531, ICM532, and ICM533). Both the ICM518 and the ICM530 series can be installed as a Type 1 or Type 2 and come in a NEMA Type 4X watertight plastic enclosure for both outdoor and indoor installation.


The ICM518 is a UL-Listed Type 1 & 2 surge protective device for 240 VAC Split Phase configuration. When a surge occurs, the ICM518 will absorb the surge up to the limits expressed in the specifications section of the guide. The ICM518 incorporates thermal protection on the surge elements (TMOVs), which allows for safe disabling of the surge protector when a surge exceeds the thermal limits of the device. A status light on the ICM518 identifies proper operational status when illuminated.


THE ICM530s are a series of Type 1 and Type 2 three-phase surge protective devices for three-phase Delta, three-phase Wye, or Delta High-leg configurations. When a surge occurs, the ICM three-phase surge protective device will absorb the surge up to the specified limitations of the device. ICM incorporates superior thermally protected metal oxide varistor technology into the three-phase surge suppressors, which allows for safe disabling of the surge elements when a surge exceeds the thermal limits of the device. There is a single status light on the controls which identifies operational status when illuminated.


“ICM continues to position itself as a leader in equipment protection. We recognize the flexibility our customers need and have created multiple configurations to meet this demand across a number of market applications,” said ICM Vice President Zachary Kadah. “Because ICM is so vertically integrated, we’re able to keep costs low, product performance high, and pass along added value to our customers.”


ICM’s entire catalog of surge protectors is available for immediate purchase:


Three- Phase SPDs
ICM530 240VAC (Delta) or 120/208VAC (Wye), NEMA Type 4X
ICM531 480VAC (Delta) or 277/480VAC (Wye), NEMA Type 4X
ICM532 600VAC (Delta) or 347/600VAC (Wye), NEMA Type 4X
ICM533 120/240 VAC (Delta High-Leg), NEMA Type 4X
Single-Phase / Split Phase SPDs
ICM517 120/240 VAC, NEMA 3R
ICM518 240 VAC, NEMA Type 4X






About ICM Controls


ICM Controls is a leading, ISO Certified manufacturer of electronic controls for the HVAC-R market and other industrial applications. Backed by over 35 years of design, engineering, and custom manufacturing expertise, ICM supports its network of suppliers, OEM and aftermarket distributors, and customers. Through its commitment to customer experience and vertical integration, ICM creates true partnerships. ICM is headquartered in Syracuse, NY.

Installation of the ICM493 single-phase line voltage monitor


The ICM493 is an advanced, single-phase line voltage monitor with a bank of surge arresters for added protection against lightning strikes. Includes a built-in 40A contactor. Housed in a NEMA Rated 3R enclosure for outdoor installations. UL Recognized. Installs easily between the service disconnect and the condensing unit. Ideal for Mini-Splits or other valuable, single-phase equipment.

  • Protects against over and under voltage, rapid short cycling caused by transients, and high-power surges
  • Ideal for inverters, mini-splits, and other condensing units
  • Easy to view, backlit digital display
  • Bank of five L-L Surge Arresters
  • Built-in 40A Contactor
  • Waterproof, NEMA–rated 3R enclosure for outdoor use
  • Easy installation and setup


Learn more about the 40A model here

Learn more about the 60A model here

Or find distributor near you