By Dana Lilly, Technical Sales Support Specialist for U.S. Boiler Company
As a qualified service technician, you are no doubt familiar with basic electrical circuitry and the testing of voltage, continuity, or amperage draw. Generally speaking, that’s all you’ll need to know 98% of the time. So why go into a discussion about power quality? Well, there is that 2% …
Power quality and reliability issues, by one count, cost the U.S. economy $119 billion each year. If you have ever found yourself at a client’s home or business, replacing the boiler control after storm-related power outages, you both have made your contribution to that dollar figure. That’s a basic example of that 2%.
Most boiler professionals probably never give a thought to the issue. After all, “the other boiler worked fine for 30 years” or “that’s the electrician’s problem.” The reality in the first instance is that modern residential boilers, in the name of both safety and efficiency, employ electronic controls that are far more sensitive to power quality than in years past. In the second instance, replacing a control that has failed (for no apparent reason) six months after you installed the boiler has now become your problem. So you, as a tech working on critical equipment (the heating system) that depends on sensitive electronic controls (any modern boiler), should at least be aware of how power quality can affect your work.
Power quality events can vary widely in severity and occur very briefly across wide timeframes, making a diagnosis at any particular moment difficult, if not impossible. To properly diagnose a potential power quality issue, a power quality recording meter can be installed in an electrical system for a period of time. The recorded data that it captures can then be analyzed by a professional. Unfortunately, the cost of doing so in a residential or light commercial application can be prohibitive. One alternative is to be educated about potential issues. This is not a deep dive discussion of power quality; we’ll leave that to the engineers and electricians, but rather some information pertaining to where these issues come from and perhaps most importantly, possible solutions you can recommend to your customers before there are problems.
The Worst of the Worst…
A transient, also known as a spike or surge, is a very short duration (often less than two milliseconds) burst of voltage. That burst could be anywhere from a few volts above the normal circuit voltage up to several thousand volts. There are many aspects to power quality, but the transient is likely the most common power quality issue you will run into and the one that causes the most damage. The higher the voltage above normal, the more potential it has to do damage. Imagine applying 6,000 volts to the boiler circuit and watching what happens! Transients can be caused by lightning, power disruptions, or heavy loads being cycled on and/or off.
So, What’s a few Transients?
Obviously, a high energy transient, from something like a nearby lightning strike, is going to do some immediate damage if it works its way into a home’s power system. We’ve all heard the nightmare stories of the strike that took out all the televisions, computers, audio equipment, etc. This is an expected result of a nearby strike with no protection.
But what about the smaller transients? Even lightning strikes far away can induce transients into power lines. Turning on or off larger motor loads (such as an air conditioning compressor) or the utility transformer providing power to a building (such may occur during a storm) can also create transients. The fact is that these smaller transients can have a similar damaging effect over a longer period of time. These surges may be in the hundreds of volts and not carry enough energy to do any immediate damage. However, over time and with enough repetition, they can compromise electrical insulation at its weakest points, creating a pinhole breach between layers on a circuit board or compromising the insulator of a capacitor.
The effects can take months or years depending on how much actual energy they possess and how frequently they occur. What can be misleading is that the lightning storm three months ago may have done most of the damage, but a condenser cycling on and off may be the final nail in the coffin. While the damage would likely not be readily apparent with a basic visual inspection, the ultimate result is the same – component failure.
Great! So Now What?
So, what do we do with transients? Even a direct lightning strike can be mitigated by a devoted lightning protection system. This may be worth consideration if the building is in an area prone to strikes (the Empire State Building averages about 25 per year). Their purpose is to safely direct the energy of a strike into the ground, often through a buried grid covering a large area. But again, the chances of a direct hit are so rare that this would be a wasteful expense for most buildings.
Dealing with the smaller, more common types of transients is an important consideration for any building, and is typically affordable. This can be done on a couple of levels using good quality transient voltage surge suppressors (TVSS). Essentially, these work by redirecting all energy over a certain level harmlessly to ground. A TVSS should always be placed on the main power supply panel of the building, typically referred to as a whole house surge suppressor. As a second level of protection, additional units can be placed individually on circuits of equipment that are deemed sensitive and/or essential (the closer to the actual equipment, the better).
Most people are familiar with power strips that have built in surge suppressors for computers and A/V equipment. For the boiler circuit, you could choose one that installs into a junction box, close to the unit. It should also be installed on conductors that leave the building, such as branch circuits running underground to a well pump or to another building. Incoming low voltage systems, such as phone lines, CATV lines, or satellite TV lines, should also have surge suppressors. You may also consider installing them at the potential source of problem equipment, such as larger size condensers.
Transient voltage surge suppressors draw no significant amount of power and require no maintenance other than a casual visual glance at an indicating LED to confirm they are operational. In the event of a high energy surge, a TVSS may become sacrificial and fail. In doing so, it has likely prevented a great deal of damage. In that case, the TVSS would require replacement, but this would be at far less cost than a boiler control.
Another consideration for AC condensers would be a “soft start” device. This can eliminate the transient created by the on cycle, but not the off cycle – thus cutting the total number in half.
Ultimately, you should consult a qualified electrician and have them do a thorough site check to confirm the best location and specifications for the devices required. They should verify the equipment grounding connections of circuits to sensitive equipment. In addition, be sure that the integrity of the existing building grounding electrode and its connections are also verified. All incoming low voltage systems should be bonded to this as well. Proper grounding is imperative for these devices to function.
Overall, my recommendation would be that every boiler installer should have a conversation with their customer about the potential issues that can arise from transients. Let them make an informed decision on whether or not they want to invest in the protection that surge suppressors can offer. Ultimately, our goal is to eliminate issues before they become problems. You may have done a great job and have a happy customer for installing that money-saving condensing boiler. That elation can quickly wane when three years later you give them a bill for troubleshooting and replacing the control…and for a failed blower two years after that! This is a story we all want to avoid.
To sum it up, transients have always been a factor on power systems. They have become an increasingly significant problem with the widespread use of electronics. It’s true that most residential buildings will not have problems with damage due to power failures, and if it happens, it could take years to manifest (if at all). Chances are you’ll never be back…but there is that 2%.