By Tom Secondino, Technical Sales Support Specialist for U.S. Boiler Company
Welcome to another edition of US Boiler Report Tech Tips. We’re glad you’re here to join us. After closing out 2021, 2022 seems ready to offer no shortage of challenges. In this Tech Tip article, our goal is to help you avoid or eliminate practices and procedures that can be problematic. No one needs additional drama as we begin another year…
Many HVAC technicians seem to follow a similar development path. Initially, most techs are intimidated by the complexity and variety of equipment we encounter. This is compounded for those of us also involved with A/C or refrigeration. As we gain experience, we become more comfortable and confident. The dangerous stage comes next; we can become complacent and forget the potential for critical situations to rapidly escalate into disasters.
In this month’s article, we’ll focus on a few boiler servicing basics that we’re all familiar with but may have lost a sense of respect for.
Aside from being a popular song, as boiler techs we’re almost always dealing with a hot pressurized liquid. This can be water, water/glycol, or steam systems. Anyone who has worked with a retired Navy boilermaker will have heard stories of Navy techs walking through galleys waving a broom handle in front of them. While I can’t state this with certainty, the stories I’ve heard indicate that the steam pressure aboard these vessels can approach 600 PSI. At these pressures, steam is virtually undetectable, and waving the broom handle is a way to find these leaks. Should the handle fall into two pieces, the tech backs away rapidly.
I cannot confirm whether these stories are true, but I am very aware of the power of steam. When fully converted to steam, 1 ft3 of water will occupy 1600 ft3 of space at 0 PSI. If this expansion is rapid and unmanaged, bad situations can spiral into critical situations quickly. I’ve worked on many commercial/industrial boiler applications operating at 100+ PSI of steam and have always given them due respect. Until recently, I have never considered residential water boilers worthy of the same caution. Most central heating water boilers operate at 50 PSI or less, most typically around 15 PSI. What’s to worry about?
Excluding oddities, all boilers today utilize a pressure relief valve. To my knowledge, all manufacturers of these devices require annual testing. As a matter of fact, they conveniently provide a lever just for this purpose! Ask yourself honestly, are you checking every relief valve every year? My guess is no, because we all know that relief valves will rarely seal when manually opened after being static for several years – or in some cases, several decades. This requires a new valve and the dreaded, “It wasn’t leaking until you touched it!” conversation with the customer. Add to this the potential for the PRV (feeder) to stick when refilling and possibly requiring replacement. We are setting ourselves up for a customer relations nightmare. However…
Should a relief valve stick, pressure can far exceed the typical 30-50 PSI. Combine this with a faulty or miswired control, (discussed next!) and the results can be dramatic. As we discussed, steam occupies a much greater volume than the water from which it was generated. Should the relief valve fail to open with a boiler running out of control, when it finally does open, a substantial portion of the water will instantly flash to steam. At this point, the relief valve cannot discharge fast enough to relieve the pressure. We have seen the back of boilers with holes the size of toasters that were propelled across the basement, and in some cases through other equipment due to this issue. In almost all instances, the relief valve was found to have enough deposits around and on the seat area that the valve was restricted from opening, and the damage in the basement and other areas of the home is shocking. Worse yet, we have received calls from technicians who report that their customer plugged the valve to “stop the leak.” If you are not yet a true believer in testing relief valves, there are videos online showing what happens when a water heater relief valve is plugged, and the resulting explosion reduces a shed to splinters.
Very simply, ensure that inspecting the relief valve is part of your annual maintenance procedure. Be certain that valves operate freely and that discharge tubes are clear. Should the customer decline the inspection, add a field to your service report and have them initial and date that this portion of the inspection was declined.
As heating professionals, we’re not only required to be proficient in the combustion process, but all other systems required to make a boiler operate. Logically, this involves the electrical feed, wiring, switches, and safety devices incorporated into the boiler. While we’re not electricians, we must be able to diagnose and repair issues with the control system quickly, accurately, and safely. The safety portion applies not only to us during the diagnostic process, but also to the operation of the equipment after we leave.
Technicians are under pressure in the winter to aid customers in keeping their homes warm and the water hot. In addition, equipment is becoming more complex. Experienced techs are aging out of the industry. Business owners are becoming more desperate to find qualified technicians to service this equipment and customers are becoming more demanding than ever before. The ability to properly read a schematic is more critical now than ever before. These dynamics can lead to a very dangerous destructive spiral.
A safety device (switches, not resistive sensors!) can be bypassed during testing to determine whether the device in question is faulty. However, it cannot be left bypassed during operation for an extended period. Contractors often report during the diagnostic process that the device we are testing was bypassed by a previous technician. You cannot bypass safety devices and walk away. EVER!!!
Wiring Harness Modifications
There are many peripheral devices that require an interlocking circuit with the boiler, including air intake dampers or fans, power vent devices, etc. Please understand the reluctance any boiler manufacturer has with field modification of a harness. You own this modification for the rest of your (or the boiler’s) life. And consider that if your field modification results in damage, or worse, you are wholly liable for the resulting loss.
Should you be required to add an external device to the boiler, investigate the least invasive way to accomplish this. For instance, in gas applications, Field Controls has a device that will quickly, neatly, and safely integrate either an air intake fan or power vent unit to a gas boiler by using a harness and polarized plug that mates with the vent damper harness. Due to either to habit or lack of knowledge regarding OEM alternatives, many installers try to splice an air intake fan, damper, or power vent device directly into a boiler harness by interrupting the factory circuit.
Once, one of our team members helped avoid an RFR (Rapid and Forcible Relocation) when a technician called for help on a similar situation. The technician had basically wired the gas valve hot all the time and bypassed the ignition and safety circuits. Here’s another example. Oil boilers, such as the MPO and V8H, have two power circuits. One is a switched circuit and the other is a constant 120VAC hot wire. Miswiring these when replacing a primary can lead to a RFR. There are numerous stories like this…
Other than for testing purposes, safeties cannot be bypassed. EVER!
When wiring boilers or replacing controls, understand the function of the circuit and controls. If you do not understand, STOP, and call for help.
Be aware that should you modify a boiler control system from the OEM configuration (unless it is an approved OEM kit), you are now responsible for the resulting performance – or lack thereof!
Spend time learning or training your techs to read schematics properly. As mentioned earlier, that knowledge is more important now than ever!
With the massive effort to expand the service areas of natural gas (NG) providers, we receive many calls regarding converting an existing oil boiler to NG.
This issue is simple. Techs, and sometimes proactive homeowners, will call our tech team asking about converting an oil boiler to NG. The answer is always simple, but not always for the contractor. And the answer is; no you cannot.
At this time, our oil boilers have not completed testing with third party gas conversion burners. As a result, we cannot confirm input ratings, efficiency standards or safety in these applications. There are companies that make conversion burners for these applications. However, U.S. Boiler does not recommend or support any installation of a conversion burner in our residential oil products.
As mentioned earlier, this one is simple. No conversion gas burners for our residential oil products.
As with newborns, it can be challenging to get boilers to eat their food. What comes out the other end is even worse. After we get boilers to properly eat and digest their food, we must manage the resulting gases. These gases are carrying byproducts of combustion, one of which is carbon monoxide.
Some of our products rely on natural draft, such as our oil boilers. In addition, most oil products, as well as a fair number of gas units, do not have spill switches. A blocked chimney can result in a boiler (or many other appliances) not venting correctly. In contrast, some of our units use inducers to discharge combustion byproducts. Many of these units, particularly high efficiency products, have a condensate trap.
Elevated ambient air concentrations of Carbon Monoxide are hazardous and poisonous. Blocked chimneys/vents can cause flue gas spillage. Unprimed condensate traps can create a direct path for flue gases to discharge into the boiler room.
Be sure your complete venting system is clear and in good repair. Vent connectors and flue passages should be cleaned and inspected during annual maintenance. Condensate traps should always be primed at installation and after service. Traps must both be fastened securely and checked annually for leaks, defects, or deterioration.
Each of these boiler servicing safety considerations could fill an entire Tech Tip article, but the goal of this installment is to get you thinking about some of the basics and how you can keep your team and customers safe. There are many other safety aspects in our trade which I would like to include, but that space does not permit. My plan is to make this a series that will cover a few items in detail in future articles. We are always interested in your feedback regarding current articles or suggestions for future topics. Please feel free to reach out to me at firstname.lastname@example.org with questions or comments.
In closing, your goal should be to keep your customers warm, and both your customers and technicians safe. Giving some consideration to things we may take for granted can help avoid unnecessary risks or problems. There is a tremendous shortage of qualified technicians in the world today. Let’s be safe and keep them around as long as we can! As always, U.S. Boiler would like to thank all our partners and we wish everyone a safe, warm, and happy 2022!