Do you want to learn exactly why your heating system burns more fuel than it should? Of course you do, or you wouldn't have found this article. Following are answers to the questions you have, or ones you didn't know you had. I will explain (in defined technical terms) how your heating system is likely to be costing more to heat your home or commercial building than it should and what you can do to reduce those costs.
Anyone who drives an automobile knows that certain cars use less gas than others. The same is true for heating equipment and like gas-guzzling SUVs, some heating systems consume enormous amounts of fuel. The difference between cars and heating systems is cars offer many benefits beyond the primary one of transportation. Cars have performance, comfort and visual appeal, as well as can be a status symbol. Heating systems are tucked away in a basement, attic or closet and their operation and performance are a mystery to most not in the Heating, Ventilation, Air Conditioning (HVAC) trade, and still a mystery to many in the trade - so-called, "professionals" (a term I use loosely throughout this article).
To clarify, I may interchange the acronym HVAC for heating, and vice versa, but this article is about heating systems, how they work and how they often burn excessive amounts of "fuel" - gas or oil.
Most building owners know how to set the thermostat, change air filters and check the fuel level on their heating fuel tank gauge, but that is about the extent of their heating system knowledge. Typically, building owners do not want to know how their heating system works; it seems too complicated and futile. They prefer to leave the technical aspects to the service personnel they have come to trust. Did I say "trust"? There are many reasons to examine your trust for your heating service company, fuel supplier and General Contractor if you are having a new building constructed - residential or commercial.
For starters, do not assume that the professional you hire to design, install, service or maintain your heating system is qualified to make all the right decisions in those respective aspects of the HVAC trade. Just as in most professions, heating professionals are often types who could care less about the quantity of fuel a heating system ends up consuming and costing its owner; their paycheck at the end of the week is more important to them. The majority of HVAC tradesmen have never been to school to learn the innumerable facets of the interrelated technologies. Moreover, many have never finished high school! But let's not get personal. Mostly, tradesmen have gathered their knowledge through hands-on experience. Experience comes in two flavors: good and bad. If the on-the-job-training has been with lousy 'teachers', then the student will be a lousy apprentice and graduate to becoming a hopelessly old dog incapable of learning new tricks.
It's not only ignorance and bad attitude that have a hand in your fuel-hungry heating appliance's performance, though I wish it were. Deliberate sales of terribly inefficient heating equipment plays a huge role. Sadly to say, American made boilers and furnaces are among the least efficient in the world and continued sales of them guarantee that fuel companies will find you to be a better customer - you will buy more fuel! Greed will often lead to corruption, with most of the corrupt getting away with it. This is a significant reason for my writing this expose.
I have no specific desire to be confrontational with specific companies, though I know them well, but I can't close my eyes any longer, knowing that we are all heading toward a dead-end with our consumption of natural resources. Fossil fuels are limited, they say the planet is heating up and polar bears' extinction in 50 years is all but inevitable. But the more we consume the more we strip forever from the planet its resources and the little is left to meet the needs of its inhabitants in the future. Must we consume until we've proved that the human species is the most insidious parasite the planet has ever known? Do we only take and put nothing back? At least we can take less of the fuel we use to heat our homes, businesses and industries and save money as we do it.
As a precursor to understanding how your heating system works, it is essential to understand the basic terms used in the industry, so let's start with the industry players, then we'll move on to dispelling the mystery surrounding the more technical aspects.
Fuel Companies - "Fuel" is a general term I use to cover any fossil fuel type such as, fuel oil, kerosene, natural and liquefied petroleum gas (LPG), methane, butane and any other petroleum-based gas types that I may not have listed here. Distributors of these fuels have one goal: to sell ("market") as much fuel as they can, to whoever will buy it and for the highest price. Period! They do not have your best economic interests in mind. They are the well-known petroleum giants, names emblazoned on tractor trailer tanks barreling down highways; large publicly traded utilities and your local fuel company with warm 'friendly' ads in the media. Fuel companies have the most to gain by inefficiently designing, installing and servicing your heating equipment. They want to deliver as much fuel at each delivery stop as possible. I know, I used to deliver fuel when I worked for fuel companies in the early 1980s.
HVAC Contractors - "HVAC" is a general term that is often misused and misapplied. Businesses that go under this heading tend to get involved with the installation and service of many areas of the indoor climate control realm, and it is a broad one! Not only does HVAC mean heating, ventilation and air conditioning, but also humidity control, indoor air quality and refrigeration. This player in the trade is likely to be more incompetent than fraudulent when it comes to accurately designing, installing and servicing heating equipment.
Plumbing & Heating (P&H) Companies - Many heating consumers are groomed through the ages to believe that plumbers are the same as heating technicians - they are not. The only thing plumbing and heating have in common is in the way pipes are connected - threaded, soldered (sweated), welded, glued (cemented), and more recently, compressed together with company specific connection means. P & H types rarely have mastered heating technology. I can spot a plumber-installed heating system instantly. It's one thing to be a master at piping, which many plumbers are, it's another issue altogether to know how the piped heating system works.
Handyman - Knows a little bit more than a homeowner about heating systems.
Heating Technicians - This is who you want to work on your heating system, but not necessarily one from a fuel company. Heating technicians work for fuel companies and gas utilities/suppliers. "Buyer beware!" Only half of these guys are qualified to do a good job on your system. Still, only 10% are really good, master-types who are rarely stumped and who see the big picture - the original system design is clear to them, the service history pops out like forensic science and they can make your system work with little or nothing to work with.
The aforementioned list is comprised of the standard players in the trade, but only fuel companies sell fuel, design, install and service heating equipment, which is not to suggest that all fuel companies participate in all aspects of the heating trade, nor am I saying that all fuel companies defraud their customers, most do not.
The case for burning less fuel can be easily made if everyone went out on the ocean in a boat and saw the sickening depth of pollution in our atmosphere stretching across the water as far as the eye can see. I live on the Atlantic side of the States and the prevailing winds blow off the land, bringing with it the smog generated across the country. Otherwise, watch a sunset and marvel at the orange and red hues, for they are the result of pollutants and particulates in the atmosphere that taint the natural color of sunlight.
Let us examine what goes into our atmosphere and our lungs when we breathe, when fossil fuels are burned. The byproducts of combustion of gas types and fuel oil include, but are not limited to:
1. Flue Gas
2. Carbon Dioxide
3. Nitrogen Oxide
4. Nitrogen Dioxide
5. Sulphur Dioxide
6. Soot
7. Carbon Monoxide
The exhausting of these compounds into the earth's atmosphere occurs constantly across the globe and proportionately to the amount of fuel burned by heating equipment, internal combustion engines and industrial processes. The more fuel we burn, the more we contribute to the aggregate pollution of our home - Earth. Why, then, burn more fuel than necessary?
The following terms and definitions deal directly with heating system apparatus and components.
British Thermal Unit (BTU) - The amount of energy required to raise one pound of water one degree Fahrenheit. British Thermal Units are expressed as a ratio to time -BTUs per hour (written btus/hr., or MBH, where M=the Roman numeral for 1,000; B=BTUs; H=Hour, so expressed as 1000s of btus/hr. All heating equipment is rated in BTU heating capacity. A typical residential furnace has a heating capacity of 100,000 BTUs and can heat a 3,000 square foot modern house. These are approximate numbers, of course. For an accurate BTU requirement to heat a building a Heat Loss Calculation must be conducted (see definition for Heat Loss Calculation).
Flue - The passageways that direct the byproducts of combustion out of a heating appliance.
Burner - These come in many types, but we will restrict our discussion to Gun-Type, Sealed Combustion and Atmospheric, as these are most likely the kind that are in residential and commercial buildings. Burners mix #2 fuel oil, kerosene, LPG or Natural gas with atmosphere (air), then ignite and control the combustion of their respective fuel types. Gun type burners can be seen protruding from the fronts of boilers and furnaces and burn gas and oil. Atmospheric gas burners are like the gas burner under a water pot on a kitchen stove - they are open to the atmosphere. Water heaters, Furnaces and Boilers utilize atmospheric and gun-type burners. Sealed Combustion burners are as their title implies, the combustion process is sealed tightly from the atmosphere in which they are installed, like a basement, attic or closet. Sealed combustion burners take their combustion air from the outdoors through a plastic pipe and vent their products of combustion to the outdoors through a second pipe, usually made of PVC (polyvinylchloride) or stainless steel. Gun-type and atmospheric burners generally vent to the outdoors through a chimney or mechanical venting means, called a "power-venter". While Atmospheric burners are simple and inexpensive, Sealed Combustion burners are much more complex and expensive. Atmospheric burners are mid efficiency types, whereas Sealed Combustion burners are high efficiency types.
Combustion Chamber - A combustion chamber or, simply, a chamber is almost always part and parcel of heating appliances that utilize a gun-type burner, and is internal to a furnace or boiler. Inside the chamber is where the actual fire during combustion of fuels takes place. An observation door or window allows a technician partial view of the combustion process inside the chamber.
Boiler - A cast iron or steel heat-generating vessel that utilizes water as a heat transfer medium to warm a space to a desired temperature. Boilers incorporate a burner which facilitates the combustion of fuels. Boilers can include a chamber, but don't always.
Furnace - A Furnace includes a burner, most likely a combustion chamber, a heat exchanger, a blower or fan and has ducts connected to it. The blower pulls "return air" from the conditioned space through a "return duct" and pushes it across the non-flue gas side of the heat exchanger. Once the relatively cold return air comes into contact with the very hot heat exchanger, the moving air picks up heat and is propelled toward the occupied space through the supply duct and out diffusers and registers placed in the rooms to be heated. For sake of reference, furnaces have replaceable air filters, boilers do not.
Heat Exchanger - A device that transfers heat from one medium (fire and flue gas) to that of another. Flue gas contains heat which is transferred through a steel, cast iron, aluminum or stainless steel barrier (prior to exiting the appliance and up the flue) into a heat transfer medium separated by the heat exchanger barrier. For sake of our discussion, air, water and steam are the heat transfer mediums relevant to this article that transfer the heat from combustion to space in the building to be heated.
Conditioned Space - The space within a building - residential or commercial - that is to be heated or air conditioned. We will deal with heating a conditioned space in this article.
Hydronics - Hot water or steam heating technology.
Forced Hot Water (FHW) - FHW heating systems include boilers (or sometimes water heaters) connected by pipes to heating "terminal units" like radiators, baseboard convectors, hot water coils in an airstream and radiant floor heating tubes embedded in floors. Forced hot water systems succeed gravity hot water (GHW) systems that were coal fired back in the day of their popular use. Water is heated in a boiler and is then circulated, or forced with a 'pump' through pipes connecting the boiler to the terminal units where heat is rejected to the space to be conditioned. The hot water temperature is lessened by the cooler room air that surrounds the terminal units and the water is returned to the boiler to be reheated and re-circulated in a continuous cycle that only stops when the room thermostat is satisfied by the increasingly heated air.
Forced Hot Air (FHA) - As in FHW, a heat exchanger inside a furnace takes the heat generated by the combustion of fuel and transfers it to the occupied space of a building, but through the passage of heated air inside supply and return ducts. Forced Hot Air implies the utilization of a furnace, whereas Forced Hot Water uses a boiler.
Steam - This system is the "Hydronic" cousin of forced hot water. Both transfer heat through water or water vapor - steam. Both include boilers that transfer heat from the fuel combustion process to the heat transfer medium - water or steam. Both include pipes and terminal units. Steam is created when water in the boiler boils and converts to steam if it is continually heated. Imagine a pot of water on a burner. The stove burner (gas or electric) heats the pot of water above it. Left long enough above the heat, the water boils and vaporizes upward. In the boiler the vapor rises up in voluminous pipes onward to cast iron radiators or baseboard. Steam seeks equilibrium with the atmosphere. Hot vapor has greater pressure than cooler air, so rushes for the nearest exit in a steam system into the lower pressure atmosphere in the conditioned space. Press the "Schrader" valve stem on your car tire and high pressure air rushes out into the lower pressure atmosphere - it's the same with steam in a heating system. Strategically placed air vents on radiators and condensate return lines allow the air above the water line in a steam system to be forced out of the system through them, but stop as the steam comes into contact with their internal mechanisms. Steam is the least efficient heating type, as the water temperature must be raised above 212 degrees Fahrenheit. Whereas, hot water systems water temperature can be modulated based on the outdoor ambient air temperature. The warmer it is outside, the less temperature is needed in forced hot water system water.
Heat pumps, electrically heated boilers and baseboard element, wood and coal-fired boilers and furnaces, solar and any other system types not fired by petroleum products, are not included in this article.
Limit Control - This control is also referred to as an "aquastat" in FHW systems and a "Fan & Limit Control in FHA systems. Hybrid hydronic systems - a steam boiler with a FHW loop (zone) also incorporate Limit Controls. Limit controls can maintain low temperature and high temperature thresholds in a heating system. Limit Controls come in many different types and have a myriad of applications that require a specific type of Limit Control. Limit Controls are often the device that cause excessive fuel consumption and are selected for this reason by unethical fuel companies so your system burns the maximum amount of fuel your heating system can possibly burn. You will want to check the type of Limit Control on your heating system! Read on to find out why.
Nozzle - The device in an oil burner that meters a specific amount of fuel through it and converts the liquid fuel into a vapor that can be readily mixed with air and ignited. Nozzles have 3 means of categorization: the amount of fuel that passes through it in gallons per hour (GPH) @ 100 pounds per square inch (PSI) of fuel pump pressure; the angle of oil vapor spray that comes out of its orifice; and the spray pattern - solid, hollow, or somewhere in between. Those specifications are written as an example like 1.00-80-B. This means 1 gallon of oil will pass through the nozzle at 100 PSI, 80 degrees is the vapor spray angle and "B" is code for solid. Too high a GPH and your oil burner will over-fire your furnace or boiler and start and stop too often - "short-cycle".
Burner Orifice - Like in oil burners, gas burners have metering devices and these are called burner orifices or burner "spud". The wrong burner orifice in a gas system can be deadly, as gas is explosive and when it is not burned properly and in the correct proportion to air the outcome can be inefficient and downright dangerous. Gas burners have at least one orifice but can have many, sometime too many, as you will see later in this article.
Heat Loss Calculation - Software programs exist to accept data input relative to a building's design characteristics like window and door types, sizes and U-values, structure insulation R-values, room sizes and internal heat gain like people and appliances. Once this information is entered into the program the software calculates how many BTUs are needed on the coldest day of the year to heat the building to a design temperature say, 68 degrees. There are no accurate short cuts to a heat loss calculation. Anytime a new heating system is designed it must first be preceded by an accurate heat loss calculation. For everything related to proper equipment and component sizing and selection is based on BTU generating and/or carrying capacity. Pipe diameters are limited in how many BTUs of energy they can transport with water as its heat transfer medium, just as duct sizes are limited in how many BTUs they can transport with air as the medium.Let's apply these technical terms. For starters, let's create a scenario - you want to build a new house. The first thing you do is interview several building contractors who call themselves a General Contractor (GC). A competent GC will give you a package price for construction of all aspects and systems in the new house. He will hire and manage all subcontractors from the electrician, to the plumber to the roofer, and the HVAC contractor. These tradesmen are subcontractors to the GC. The residential building trade is an extremely competitive one and the profit margins are slim. The GC knows this, so hires the people he thinks will furnish acceptable quality at the lowest price. Unfortunately, most GCs are extremely unaware of the importance of proper heating system design and the information that needs to be considered to produce the most efficient design for the money. He is also unaware of the requisite steps involved with cranking out a professional design. It is the design that determines the cost. GCs often look at the cost only. As long as the heating system "works", then the GC is happy, even though he will never know that the system will consume a lot more fuel than if it was competently designed in the first place. In fact, nobody will ever know that is, until a true competent professional figures it out, but then it is usually too late. Most would rather spend more money on fuel than replace the incorrectly designed system.
