In this episode with BENOÎT MONGEAU we talk about the components of combustion and what to consider when testing combustion on a fuel burning appliance.
We all know (or should know) that venting refrigerant is a big no-no and can result in huge fines from the EPA.
There are many other potential violations, but two that can easily occur if you aren’t thinking ahead are the disposal of mercury and oil.
Mercury is found in fairly large quantities in the bulbs of old thermostats. Instead of ditching these stats, gather them up and return them to an A/C supply house for proper recycling. Most supply houses offer this service.
Refrigerant and Vacuum pump oil are both oils that we often need to drain for one reason or another. Make sure to capture the oil in a pan (or an oil coil cleaner jug) and turn it in to an oil recycler. Many auto parts stores and auto mechanics will have no problem taking it off your hands.
In this video Bryan talks about
Refrigerants to consider
This article is written by Senior Boiler Tech Justin Skinner. Thanks, Justin.
Oil burner nozzles are present in most forced combustion air burners. They are used, with an oil pump, to atomize fuel oil and allow it to burn. Atomizing is raising the pressure of the fuel and forcing it through the nozzle. The fuel comes out of the nozzle essentially vaporized. It is then mixed with air and burned. Nozzles are also used to meter the amount of fuel being used, and to vaporize the fuel in an efficient pattern suited to the burner chamber of whatever equipment it is installed on. If you work on burners, you have probably seen and changed out your fair share, as periodic nozzle replacement is necessary for clean and reliable burner operation. But there is more to nozzles than what meets the eye. Let’s take a closer look.
The numbers on the nozzle tell us the specific rating of the nozzle, the spray pattern angle, and the spray pattern type. The nozzle listing here has a .75 GPM rating. That means the nozzle will spray .75 gallons per hour of fuel oil at 100 psi. Nozzles are generally rated at 100 psi, and that is the pressure that most residential style oil burners run at, but not all. It also has an 80-degree spray angle. That is the angle at which the spray comes out of the nozzle. The smaller the angle, the more narrow the spray pattern. Think of a garden hose with a spray nozzle. If you squeeze the handle only a little, the spray comes out at a wider angle. This would be similar to a higher degree spray angle. As you squeeze the handle more, the outer edges of the water get closer together. A closer spray pattern would be a smaller angle. Larger spray angles are generally used for wider, shorter burner chambers, and smaller spray angles are used for narrower, shorter chambers.
The letter on the nozzle indicates the spray pattern. Different manufacturers use different letters for the same patterns, so we will use Delavan as the example, as it is the most common nozzle manufacturer I use. Patterns are designated as solid (B), hollow (A), and semi-solid (W). A solid nozzle indicates the vaporized oil is distributed evenly throughout the entire spray pattern. A hollow nozzle distributes more of the oil to the outer ring of the pattern, and a semi-solid is neither. W nozzles are typically considered a replacement for both A and B nozzles, although that is not also the best option. I prefer to replace nozzles with the type and pattern specified by the manufacturer, but late nights and on-call situations do not always allow it. Typically the nozzle is designed to fit the equipment and not the other way around, so using the correct nozzle can save you a lot of headaches and a sooty mess.
The pictures above show an exploded nozzle. The back portion is a very small particle filter. It is composed of thousands of bronze pellets fused together. This filter is easily clogged by gunk, so an in-line filter should be used to catch most of the fuel sludge and trash before it gets to the burner. After the filter, a slotted distributor is present. The pressure of the fuel from the pump causes the distributor to spin, and the oil increases velocity inside of the nozzle. The oil is forced through the head of the nozzle, which contains a small hole/tube. The sudden decrease from high velocity/pressure to atmospheric pressure through the tube causes the fuel to vaporize. Once the vaporized fuel leaves the nozzle, it is mixed with air at the burner head and is ignited if the fuel/air ratio is correct and the ignition source is strong enough. Nozzles are rebuildable if you need to in a pinch. But they are finely machined to exacting specs, and fairly inexpensive. So I would only try to rebuild a nozzle in an emergency situation.
Nozzle flow is rated in GPH @ 100 psi pressure. One gallon of #2 fuel oil contains approximately 140,000 (give or take a 1000 or 2). So a 1 GPM nozzle @ 100 psi is a 140,000 BTU burner input. If the burner efficiency is 80%, that means 20% of the fuel energy goes up the flue as unused energy. So a 1 GPM nozzle on an 80 % efficient burner is equal to around 112,000 BTU’s available from the fuel. But what if you need a 1 GPM nozzle, but you only have a .75 GPM nozzle available? Well, increasing the pump pressure above 100 psi can allow for the same amount of fuel input with a smaller nozzle.
As the chart above shows, the same nozzle flow rate can be achieved with a variety of nozzle GPM sizes and pump pressures. It’s not advised to change nozzle size or pump pressure during an inspection unless there are issues. It’s more to get you by until you can get back with the correct nozzle. Also, if you change the nozzle size or pump pressure outside of what the manufacturer recommends, make sure you note it on the equipment for the next tech who may go behind you. It’s also an option to downsize the nozzle GPM and increase the pump pressure for hard/smoky light-offs and shut downs. The higher velocity from the increased pump pressure allows for the complete vaporization of the fuel. This allows for a cleaner light off, cycle, and shut down.
This article is the second in a series on boiler basics by senior boiler tech Justin Skinner. Thanks Justin.
There are many types of boilers that do a lot of different things, but most all of them have some of the same basic components. Some because they are required by regulatory agencies, some because they are necessary for proper operation and safety of the boilers. But no matter how large or small the boiler is, you can probably find most, if not all of these components.Unless noted otherwise, these are typical for hot water boilers.
Every boiler needs some source of heat, obviously to heat the water. The type and sizes of burners vary so much that a few complete articles would be required to really get into detail as to how they operate and the specific operations of each burner. All burners serve the same function, which to safely and efficiently burn fuel and create heat. Typically, the flame safeguards are integrated in the burner control sequence, in that certain conditions need to be met in order for the flame to light, similar to gas furnace pre-ignition sequence of operations. A blower with air dampers for adjustment is often part of the burner, and air/fuel ratios are adjusted at the burner during combustion analysis. Ignition transformers/control boards, ignitors, draft pressure switches, flame sensing devices (flame scanner/ flame rod), and a primary controller to sequence all of it together are all apart of most burners. Honeywell, Fireye, Siemens, and a few others are common burner controls that are all different, but essentially do the same thing. Some of the most common burner manufacturers ( at least in my world) are Powerflame, Webster, and Beckett, but there are a lot of burners out there. It is common to see a dual fuel set up on larger burners, meaning they are capable of burning 2 types of fuel, typically gas and oil. Steam and hot water boilers both use burners.
Most water boiler systems are sealed, meaning that they are filled with water, the air is bled, and the same water is circulated throughout the system. In a perfect world, no additional water would be required, but most systems lose water and pressure through a variety of ways. A automatic water feeding valve is used to keep the system at a set pressure. There are many types with many different pressure ranges. The proper term would be pressure reducing valve, but i’ve always heard them called water feeders, so that is what I call them here. Back flow preventers are often used with water feeders. Once the water enters the boiler system, it should not be allowed to go back and re-enter the domestic cold water system. Boiler water can be pretty gross, and often contains chemicals for water treatment so be mindful and safe when opening the water side of any boiler system.
Pressure/Temperature Relief Valves
Relief valves are used to protect the boiler pressure from rising above the safe maximum that the boiler is rated for. The pressure rating on the relief should never be above the pressure that the boiler is rated for. Also, relief valves come with a BTU rating and are sized to match the fire ratings of the burner. This is crucial to keep in mind when replacing a relief valve. A valve that is too small may open prematurely, and a valve that is too large may not open at the pressure it is supposed to. There are calculations and recommendations that are used to size relief valves that I’m not gonna give here, but if you are replacing one or having issues with one and you are unsure, ask a senior tech or contact the manufacturer for recommendations. But keep in mind that the relief valve may be the last line of defense in preventing a boiler explosion, so treat it as such. NEVER plug a leaking relief valve, it is kind of illegal. Found on both steam and water boilers.
Operating/Modulation/High Limit Controls
These are controls to maintain a set range for water temperature, the burner modulating from high to low fire (for modulating burners), and as a safety to prevent temperature rise above set point. These are used in both water and steam boilers, and i will go over them in more detail in the next article.
Are used to move water through the boiler and the system. Some pumps are controlled on and off by the boiler, some are controlled by building automation, some are just on and run constantly. Flow sensors are often used to insure proper water flow is present in the boiler, and will disable burner operations if the flow is decreased below what is recommended.
Pumps come in all shapes, sizes, and voltages.
Low Water Protection
When a boiler gets low on water, it can be a very dangerous situation. Low water safeties are used to disable the burner when low water conditions are present. Steam and water boilers both require protection, but low water controls for steam are generally much more crucial than a typical water boiler, as the risk with steam and boiler low on water can be severe.
This is by no means a comprehensive list, just a general overview, and I’m sure i missed something that you all will let me know about. With the huge variety of boilers out there, it would be tough to list every single thing that you might run into. These are all very common and the things that i seem to replace or have issues with the most. I will expand on steam specific controls and components in the next article.
Electronic leak detection is a critical part of any HVAC technicians common practice. Unfortunately, it is also one of the most common sources of misdiagnosis. Here are my tips to make your leak detection more successful.
Use Your Detector Second
Before starting to use your detector STOP! look for signs of leaks and corrosion throughout the entire system. I see so many techs who use an electronic leak detector with a very large leak when they would have been better served pressurizing and pinpointing the leak with soap bubbles.
Get a Good One
Use a good quality leak detector. Hint: If it costs less than $300 it probably isn’t great. I am fan of the H10G and the H10Pro although we are testing the Tifzx-1 as a possible option on the recommendation of a few good techs I trust.
Test Your Tools
Check your detector and make sure it actually works EVERY TIME. The H10G has a reference bottle for testing.. USE IT
Let it Warm Up
Many leak detectors require a warm up time for the sensor. With the H10G I allow it to run for at least 5 minutes before I start to use it.
Start at The Top
Most refrigerants are heavier than air, starting at the top and working your way down will help keep you from picking up a leak below the actual point of origin.
Move really slow and when you do get a hit, remove the wand, let it clear and go back to the same point a few times before calling it a leak. Once you think you found a leak, attempt to use bubbles to fully confirm.
Use Common Sense
No matter what leak detector manufacturers tell you.. there ARE other substances that can trigger your detector and refrigerant can move from one place to another due to drafts. I have seen several cases where chemicals in a garage are triggering the detector or where a tech has misdiagnosed an evaporator coil because of a chase leak where the refrigerant is being pulled from beneath the unit into the return. Look around and make sure there is nothing causing interference.
Before you condemn that coil BE SURE. Use all of your resources to positively confirm the exact location of the leak. A little patience goes a long way.
We all see a lot of questions about, dyes, leak stoppers, lubricants, inhibitors and snake oil.. all designed to go in the refrigerant circuit and “improve” something.
I just go back to what Ray Johnson always said (Ray is one of my early heroes in the biz and taught me a lot at Carrier classes)
“Oil and refrigerant”
If it isn’t oil and refrigerant, it doesn’t belong in the system.
Now I know there are rare exceptions… Heck, Carrier has a tech bulletin from 2014 dictating that Zerol Ice should be added to certain systems due to TXV sticking issues.
But when in doubt.. Just oil and refrigerant.