What is a Steam Trap?

Steam based heating systems are similar to hot water heating, but they’re not quite the same. In a hot water system, liquid water enters, circulates, and returns to the furnace. This is not the case for a steam system. In steam, hot steam leaves the furnace, and water returns. This may seem like a minor difference, but it has massive implications to system efficiency. The Science of States When steam cools down, it becomes liquid water and falls down to the bottom of the heating system. On the one hand, this means less plumbing needed to capture and reheat the water. On the other hand, it means we have mixed-temperature fluids in the same space. The condensed water will absorb  heat and hinder the operation of the heating system. It’ll cool down the radiators and the steam itself. The big problem is that water takes a lot of energy to move from being liquid to being steam. It’s not a linear graph. When you heat the water, it’ll eventually rise to the boiling point, about 100 C at sea level, and then the temperature won’t actually increase. The molecules in the water will start to absorb the energy until it’s enough to breaks the hydrogen bonds between them and form steam. As you can see in the chart, we continue to add energy into the system, and between states, the temperature rises, then we hit a limit. When its time […]

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Why Steam Heat?

There are a lot of ways to heat your building. Forced air and hot water heat are the most common today, but it’s also possible to use steam.  You might think that steam and water based systems would be almost the same, but they’re actually very different. The Cheap Installation In a traditional hot water system, water flows from radiator to radiator, then back to the furnace to be reheated and recirculated. In a steam system, you don’t need that return pipe. When the steam condenses, it’ll collect at the bottom of the pipe and drip its way back to the furnace the same way it came. The hot steam meanwhile will fill the top of the pipe. This sort of system has traditionally been incredibly popular in tall buildings, such as the skyscrapers in New York city. Being able to use just a handful of stand pipes to provide heat to the entire structure was a massive cost savings. You could essentially build a heating system with half the pipes involved. At the same time, steam heating could be incredibly efficient for a zone-like installation. Many radiators featured shut off valves, allowing a room’s occupant to manually manage the heat. Unused room? Shut off the valve. Too hot? Shut off the valve. It was manual work, but in the right setting, it saved on heating needs. Once one of these radiators became heated, they would also provide heat for […]

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How We Measure Boiler Efficiency

Air conditioners are rated with a SEER number that indicates how efficient they are. Higher numbers means better performance. We have a related system for furnaces, though it’s a little different. Heaters use the AFUE, Annual Fuel Utilization Efficiency. Fuel to Useful Heat In any combustion system, there’s just about guaranteed waste. In a car, there’s wasted heat and wasted work, where we don’t use all the energy generated by combustion. In furnaces, we concern ourselves with wasted fuel. Depending on the design of the burner, the ignition system, and the fuel type, some amount of fuel will be exhausted without having been burnt. Determining the fuel lost for this efficiency is generally done in lab tests when the furnace is being designed. The manufacturers measure how much fuel goes in, capture the exhaust, and use lab equipment to detect how much fuel is in the exhaust. This fuel is lost because it just never got the chance to burn in the combustion chamber. Some fuel sources burn slower, sometimes a spark or flame doesn’t propagate through all the fuel that’s injected into the combustion chamber. It may still burn in the exhaust, but by then it’s too late. Whatever the case may be, this lost fuel never heats your facility. The AFUE scale is therefore a percentage scale. We use a range of 30%-100%. Anything under 30 is basically useless. You’re just spraying a geyser of gas in the […]

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Why is There a Belt in the Furnace?

Is it weird that we use belt drives in furnaces? Belts aren’t necessarily known as the most durable or flame-resistant thing in the world. Why would we put a belt next to a roaring inferno? It’s 2018, why don’t we just bolt the motor straight to the fan, blower, or whatever it is we’re driving?   Gear Reduction Spinning blowers, fans, and other equipment requires a lot of mechanical power. At the same time, it can take more power to overcome the friction on a resting object, especially for heavier parts or equipment that’s not perfectly supported. There can be additional friction by such offset loads. Providing enough force to move this equipment requires bigger and bigger motors. Or does it? Physics is full of tricks. We can use a concept called Gear Reduction so that a smaller motor can get the job done. Instead of outputting a lot of power at once, we output less power, but more revolutions of the motor. For every 2 rotations of the motor, the blower might only spin once. This reduction requires the motor to spin faster to achieve the same result as a bigger motor, but it won’t need as much torque to do that work. The easiest way to see this concept in action is to look at a multi-speed bike. Your gears are different sizes to allow for different speeds. In low gear, it is incredibly easy to spin the […]

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To Do: Preventative Furnace Maintenance

As with all things, an ounce of prevention is worth a couple tons of cure. After a long spring and summer of sitting little or even unused altogether, your furnace needs some attention before the long winter comes. This can vary from model to model, but in general, you can expect your HVAC Professional to do a lot of cleaning and even some replacing.   The Big Cleanout Nearly every fuel-burning heating system is going to produce some sort of soot or ash from running. Modern heating systems are incredibly efficient, but they’ll still produce a bit of waste material. This waste can be combustion byproducts, contaminants left behind in the fuel, or in some cases even microscopic particles of other components of the furnace itself, such as particles from a spark rod. This build up will cause a number of issues over time: Inefficiency, the soot will absorb heat, requiring more fuel than normal to reach the same temperature changes. Dirty emissions, by exhausting the soot out into the open air, a potential health and legal hazard. System failure, by clogging up the burner or otherwise preventing the furnace itself from running. The general process of cleaning up the furnace is straight forward. Your contractor will remove some parts of the case to get into the combustion chamber and use a vacuum to collect the soot. Depending on how much soot there is, it may be necessary to replace […]

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Winter is Coming – Prepare Yourself

Today we start to change gears and prepare for the change of seasons. Summer is coming to a close. We’re already seeing temperatures drop around Philly, with our highs falling from the 90s into the 80s. It’ll be a cooler, more comfortable week this week, with temperatures well on their way to the chilly fall norms. Now is about the time to make sure your heating system is ready for a long, busy season.   Why Check the Heater? For most people in the northern most parts of the US and elsewhere in the world, our heating systems have been dormant all summer long. You could have old, gross filters still in the system or discover a mouse has eaten the thermostat wires. There’s also that always looming spectre of hardware failure, when an old part has finally gotten old enough to just give out. It’s warm now and your AC is still running, so you don’t need your heating system yet. Your contractor can have the system apart for a good few weeks, you can use cheaper, slower shipping, and suffer no ill effects for it. This is also a good time for simple, routine maintenance. You can take this opportunity to swap out your air filters, have your chimney cleaned, clean out the furnace, and so on. Different system designs accumulate differenent maintenance needs. Oil burners often need a good cleaning to remove soot, for example.   What […]

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Oil Burner Ignition

Gas systems need either a hot surface or a pilot light to get started, but not oil systems. Why the difference? It boils down to the fuel being fundementally different. Fuels like propane and natural gas enter the combustion chamber in a gaseous state. Once part of that material is lit on fire, it will conduct the heat and light the entire fuel stream. This doesn’t work for oil.   The Major Difference Oil enters the combustion chamber as a liquid and it requires extreme heat to light. This makes a pilot light nearly pointless, as it would be just as easy to light the main burner as the pilot. A hot surface igniter would be a viable option except it needs to be in the path of the fuel stream, where it would endure the direct-heat of the flame throughout operation. Oil as a fuel source is a completely different beast, unrelated to gas heating. These problems all stem from heating oil’s chemical make up. It’s a cousin of diesel fuel used in over the road trucking, but thicker. It shares some of diesel’s inherent safety. Heating oil and diesel require either extreme heat or extreme pressure. This is why diesel trucks don’t have sparkplugs. At least for an engine’s needs, a spark wouldn’t work well in the long run. They generally remain in a liquid state as well, rather than readily becoming gasses.   A Really Big Spark […]

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Gas Furnace Ignition

We’ve talked a lot about the safety systems keeping your furnace from burning down the building or blowing up your building. This all begs the question: how do we get the flame started in the first place? It’s actually not a fully straight forward answer, and it varies by fuel source and furnace design.   The Old Fashioned Pilot Light In days long-gone, a furnace needed a constant flame to light it’s burner. This was called a Pilot Light. It was just a tiny, constant little flame like a lit candle. When the burner started, it simply had to turn the gas on and the pilot would ensure that the whole burner lit afterwards. The solution worked well enough, but by modern standards is an incredibly wasteful way to run a furnace. In systems with an always-on pilot light, fuel would always be getting burned, even if there wasn’t heating anything. Overtime, this adds up to hundreds and thousands of gallons of wasted fuel. It certainly worked for a time when we had no better alternatives but it’s a relic in today’s high-efficiency world.   Intermittent Pilots One of the major hurdles of moving on from a pilot was creating enough energy to light the fuel. It takes more than just a spark for ignition, it can take significant voltage. Between the fuel mixture, spark size, spark temperature, and everything else, it’s a difficult ballet to directly, electrically light a […]

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