Maintaining High-Efficiency Boilers
High-efficiency boilers especially benefit from the right maintenance because of the technology inside.
Jan 26, 2021
By John Smart, Technical and Training Manager, Weil-McLain
Popular high-efficiency boilers tend to be more expensive at installation, but lower utility bills pay you back over time. In fact, the U.S. Department of Energy estimates that replacing an older boiler system with a new, high-efficiency one can cut fuel bills by up to 40%. However, to protect that investment, high-efficiency boilers need to be properly maintained, just like you would with a car.
Two key parts of a boiler are the heat exchanger and heat engine. Put simply, the heat exchanger transfers heat from the combustion process into the water that’s circulated through the building. The more energy the heat exchanger can transfer, the more efficient the boiler is. High-efficiency boilers extract heat so efficiently that the flue gases leave the boiler at temperatures low enough that they actually condense inside the heat exchanger.
Why high-efficiency boiler maintenance is important
High-efficiency boilers especially benefit from the right maintenance because of the technology inside – some achieving upwards of 95% efficiency. The intense environment inside a high-efficiency boiler should be monitored and serviced to maintain peak efficiency and keep things comfortable:
The combustion and extreme temperatures created in the heat exchanger in order to heat the water can lead to residue.
Rapid temperature changes form condensation and combustion byproducts, which can lead to drainage clogging.
A byproduct of the combustion process can mix with condensate and raise pH to damaging levels.
The repeated firing of the boiler flame wears on the flame rod sensor
the boiler depends on.
Air intake pipes can accumulate debris and can stall the system.
The air intake pipe or vent could be clogged causing your system to occasionally stall out or lock out, which will leave you without heat or hot water.
Water levels must be maintained properly to prevent permanent damage.
Routine boiler inspection checklist
Whether you’re a homeowner or a building professional, there are routine steps you can take to keep your high-efficiency boiler performing. Some of these you can do in passing, others are more involved and can be done less frequently. If you notice any issues, we highly recommend you call the contractor who installed the unit for a solution. Here are some of the inspection and maintenance steps to take at your home or facility:
Check the air vents and flues for any blockage and clear, if able.
Look at the pressure gauge to ensure the water level is staying about the same—system pressure declines as water is lost.
Keep an eye out for dripping water, it may indicate pressure issues.
Clear the area around the boiler. Boxes, bags and other items should be moved away from the boiler to allow it to breathe. Always keep chemicals such as solvents and cleaners away from the boiler.
Check piping for any signs of leakage or deterioration.
Examine the condensate drain line, PVC fittings, drain system and drain trap for blockages.
Book an annual boiler service appointment
Boilers should be inspected and serviced by a professional installer or technician at least once a year. Even if you’ve taken good care of your high-efficiency boiler, the trained eye of a professional can address smaller issues and prevent bigger more expensive repairs or replacement – again, to protect your investment. Each contractor is a little different, but during a tune-up or maintenance visit, technicians will typically:
Clean and inspect the heat exchanger for wear and tear
Check and clean the burner assembly
Test the low-water cutoff
Ensure all electrical wiring is intact and joint/pipe connections are secure
Test water pH levels to make sure they are in a safe range
Clean, flush and inspect condensate systems
Make sure the system operates properly, by testing and cleaning sensors, ignitor and burner assembly
Check the venting system for deterioration, corrosion or blockage
Check settings and test the safety and operating controls
If system water is dirty, power flush the system piping to maintain efficient water flow
Check for correct boiler operation once the boiler has been cleaned and examined
Additional Servicing Tips
It’s best to service a high-efficiency boiler when temperatures outside are not too extreme and as close as possible to when you’ll turn the system on for heating season.
Servicing a boiler will make it more efficient. The unconstrained flow of air, water and power is critical to performance. Leaky and/or clogged pipes or air vents force the system to work harder than it needs to, negating efficiency.
Servicing hydronic system piping as well as the boiler are critical in maintaining the boiler’s efficiency. Dirty system water will not absorb as much heat energy as clean system water and will degrade the heat-exchanger’s ability to transfer heat energy into the water, therefore reducing its efficiency. Clean system water and piping maximize the boiler's efficiency.
Also, through the season, combustion byproducts will deposit on the heating surface in the heat-exchanger, preventing some heat energy transfer into the system water. Removing these byproducts annually, before the heating season, will restore the boiler to peak efficiency.
High-efficiency boilers are relatively new in the grand scheme of heating equipment. Servicing them on a regular basis will help ensure their longevity for years to come.
To learn more about the full line of high-efficiency boilers at Weil-McLain, visit https://www.weil-mclain.com/full-line or contact a Weil-McLain regional sales office at https://www.weil-mclain.com/locations .
John Smart is technical and training manager with Weil-McLain , a leading North American designer and manufacturer of hydronic comfort heating systems for residential, commercial and institutional buildings. Founded in 1881, Weil-McLain is based in the Chicago suburb of Burr Ridge, Ill., with manufacturing facilities in Michigan City, Ind. and Eden, N.C., and regional sales offices throughout the United States.
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What COVID Means for IEQ
The coronavirus has exposed the weaknesses of our indoor climate systems to protect us.
Jan 26, 2021
I want to talk about COVID-19, but I want to make it very clear from the beginning that I am not a doctor. When I was young, I did want to be a doctor. But, then I found out you had to have a high school diploma, and that ended that.
Having given the disclaimer, you don’t need to be a doctor to see that the coronavirus has changed the world. Many of the changes will be permanent —or at least some variation of permanently different. Which means that whatever business model for construction you were using yesterday will also have to change, or you will lose business tomorrow. More to the point, you will miss business opportunities tomorrow.
Working from home these past several months has shown that for many people in the workplace with office-type jobs, it is indeed possible to work from home with little or no loss of production. Many people that I talk to say they are busier than ever working from home, and with technology what it is, they feel they are getting more done with fewer interruptions.
I suspect that part of the fallout of this will be fewer commercial office spaces built and a huge spike in remodeling construction, as current office facilities are being repurposed and reimagined for the post-COVID world.
I believe that the re-pipe and reconstruction business could pass the commercial new-construction business within two years, as building owners scramble to realign with the new normal.
Not surprisingly, one thing that has really changed since all of this started is that the conversation around indoor environmental quality, or IEQ, has exploded. How we build and how we live in these buildings is going to change—you can count on it.
The coronavirus has exposed the weaknesses of our indoor climate systems to protect us. Not just from the virus, but also allergens, volatile organic compounds (VOCs), microbial contaminants (such as mold and bacteria), gases (such as carbon monoxide and radon), and carcinogens such as asbestos, formaldehydes used in glues, styrenes used in fragrances, lead, PCBs, and coming soon — PVC, commonly found in toys and shower curtains. As it turns out, a well-vacuumed and well-shampooed carpet has 4,000 times more bacteria living in it than is on your toilet seat.
So, it would seem that the best thing you could become tomorrow is more well-versed in ventilation and infiltration. It will profit you to know how filtration works, how to decrease infiltration and increase ventilation with a minimum loss of heat energy.
New technologies are appearing on the market to address these COVID issues, like ultraviolet germicidal irradiation and needlepoint bipolar ionization, which are being used in commercial spaces to go to war against the virus with the side benefit that our indoor spaces will become safer and healthier. The important takeaway is that the building-systems types are going to change, and there may be greater opportunities for retrofitting existing buildings. This could translate to more re-pipe opportunities.
Forced air vs. radiant. Image: Uponor.
One of my colleagues here at Uponor, Business Development Manager Devin Abellon, is an engineer by training and a person very much in touch with commercial-building trends. He told us recently that —
“Another thing the pandemic has done has forced our industry to change how we design our buildings—the processes we use. Shortly after the pandemic broke out, we watched as China built two massive hospitals in less than two weeks, using an integrated design process and modular construction. Two weeks—that’s how long it takes an engineer in the U.S. to review a pump submittal. But, they built two hospitals. We also saw how they built a 57-story high-rise in 19 days.”
Devin pointed out correctly that we in North America are behind the rest of the world in commercial-project cycle length. The rest of the world has learned to shrink this process, thereby reducing waste while building higher-quality structures on time and on budget — something that rarely is done in North America.
So, to kick the football down the field, I’d like to start modestly with a discussion of infiltration and filtration as a starting point.
Air movement in and out
Infiltration is the unintentional introduction of untreated outside air into a building, typically through cracks, doorways, and leaks around insulation in windows or other penetrations. When infiltration happens, it is unfiltered and unheated, which has a negative effect on the structure’s IE.
Exfiltration is the leakage of air out of the building, whether it is intentional or not. This is air that you have already filtered, heated, and dehumidified. Again, this diminishes the IEQ. Exfiltration comes from bathroom fans and oven fans that can, in some cases, move up to 500 cubic feet per minute (cfm) out of a house. This ex-filtrated air must be replaced. And again, it is with unconditioned air.
We need fresh air to provide oxygen and remove potentially harmful carbon dioxide buildups. Different types of occupied spaces have different requirements about how much fresh air we need to bring in.
A house might need to have one half of an air change per hour to meet the fresh-air needs of the occupants. An office might need two per hour to meet the fresh-air requirements; a manufacturing space, six. These requirements have been published in ASHRAE publications to guide us in our buildings to give us a safe indoor air quality.
So, let’s see how infiltration and exfiltration affect our buildings. Suppose we have a 3,000-square-foot house with 8-foot ceilings that requires half air change per hour.
3,000 ft2 x 8' ceilings = 24,000 cubic feet of air. At half air change per hour, that means 12,000 cubic feet of air must be replaced every single hour to keep us healthy.
Picture a basketball: It contains almost exactly 1 cubic foot of air. With half air change per hour, we are taking 12,000 basketballs full of heated, filtered, dehumidified air and putting them outside, while bringing in another 12,000 basketballs that need to be reheated, filtered, and dehumidified. This is the cost of having healthy air.
But let’s say that the infiltration/exfiltration of the house—through cracks in the walls, large oven fans, leaks around doors and windows—adds another half air change per hour, which is not unusual at all.
That means you are losing 24,000 basketballs of heated, filtered, dehumidified air, putting it outside, and bringing in all that unheated, unfiltered air into the house every hour of every day of the heating season. If this house was built back in the 1950s or ‘60s, it could be even more than that. Environmentally and economically, caulking up the cracks is just as important as how much insulation we put around a house.
What if someone is sick?
Apart from the tremendous loss of heat and conditioned air, if someone in the house who is infected with the virus is coughing and sneezing, tiny virus particles in respiratory droplets could be circulated in the air.
Anything that moves air currents around the room can spread these droplets: an air conditioning system, a window-mounted AC unit, a forced-air heating system, or even a fan. As you can see, infiltration and exfiltration directly affect the movement of air in a space.
Counting on the furnace filter to stop the spread? It is almost no help at all. Imagine standing in front of a chain-link fence with a pile of BBs in your hand. One by one, you throw a BB at the chain-link fence. What do you think the odds are that the chain-link fence will stop even one BB? A BB to a chain-link fence is a fairly accurate representation of the coronavirus to a home-furnace filter.
Indeed, furnace filters are of little value as far as health goes. Did you know that those filters are not meant to purify the air you breathe? Who knew? Their sole function is to keep larger particles of dirt, dust, hair, etc. from clogging the furnace and air-conditioning equipment.
Dirt, hair, etc. can clog coils, coat electric motors (causing overheating), and coat fan blades (causing inefficient air movement). The typical fiberglass furnace filter doesn’t meet a single requirement of nursing homes’ and hospitals’ filtration needs. They don’t even stop that much dust and hair. That’s why this country has a thriving duct-cleaning service business.
Minimum filter efficiencies are specified in Table 6-4 of ASHRAE Standard 170-2013. The MERV ratings are based on a test described in Appendix J of Standard 52.2. The MERV ratings more accurately predict filter efficiency over time, so hospitals and design engineers should require MERV-A ratings when ordering or specifying filters.
Below is a chart that will help you distinguish the different MERV ratings of filters.
The coronavirus itself measures 0.06 to 1.4 microns (based on varying expert opinions). They are most often connected to a moisture droplet, which brings their size up in the range where HEPA filters are more successful. We have a ways to go yet
So this is where we are headed. In that vein, it makes sense to start focusing on indoor climate systems that actually don’t have anything to do with circulating the air—like hydronics. Hydronic hot-water heating, chilled-water cooling, and radiant heating and cooling systems can provide better IEQ and, in turn, better health.
It’s a fact that your choice of heating and cooling systems does make a difference. In this new era of the coronavirus, we need to start focusing on building solutions that will have a positive effect in terms of health, comfort, and energy efficiency.
I would be grateful to hear your thoughts, ideas and stories. Until the next time, best regards and happy heating.
Steve Swanson is the customer trainer at Uponor Academy in Apple Valley, Minnesota. He actively welcomes reader comments and questions at firstname.lastname@example.org .
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