Who would disagree that unity is one way to a happier family? And isn’t the biggest single component to a successful business, marriage, partnership-you name it- teamwork and agreement? Does this not signify integration? On a global scale, system integration has solved many problems. In Detroit, a system of co-generation was devised just after the turn of the 20th century. This system capitalizes on energy created by the movement of natural gas through pipelines to create electrical energy. This has exemplified efficient energy usage for almost a century, paving the way for other cities’ cogeneration systems.
Just last year I lugged around three items, all of which were critical to my success as a businessman, or so I thought. They were a phone, a laptop and a PDA (personal data assistant). I used the laptop to show presentations in homes and businesses and for quoting jobs on site; the PDA for photos, calendar and schedule; and the phone for, well, you know. Now I have a nifty little device called a Treo. It’s a palm for photos, calendar and contact manager. It also has a program that uses the Quick Books conduit so I can quote jobs on site. Furthermore, it can do presentations, carry all my PDF files for my specification and installation documents, has a Word and Excel portable file converter so I can create any documents on the go that I did on my laptop, and it’s a phone too! All this is integrated into something that fits in my palm. It has recently occurred to me that this is not unlike what our company has been doing with integrated systems for space heat and domestic hot water for 15 years. Using the infinite modulation of the modern tankless water heaters, we are able to create space heat and domestic hot water from one appliance. Infinite modulation means it only creates the BTU’s needed to heat the building or hot water at the time it’s needed. In other words, it never “over-fires” like a standard furnace will.
For example, a conventional furnace is nothing more than a box with a fan in it, right? Most heating contractors would like us to believe their brand of furnace has a unique quality about it that makes it better than someone else’s brand. It simply isn’t true. It’s difficult to improve on such archaic technology (I’m not even sure technology is the right word here). In 1988, Reagan enacted the N.A.E.C.A. (National Appliance Energy Conservation Act). This included air conditioners, refrigerators, small home appliances and furnaces. The mandate for furnaces was, at that time, 80% efficiency. It’s no coincidence that the 80% standard still stands today, 19 years later. The only real difference between a standard furnace of that time and the new furnaces was a combustion fan. This was a secondary fan that regulated the flow of heat through the heat exchanger, helping to keep more of the heat in the air stream. It also had no pilot light, instead using an electronic ignition. The combustion fan also served to keep cold air from dropping down into the heat exchanger and cooling it off. Unfortunately, these appliances still require outdoor air for combustion, so there was (and still is) the issue of cooling off a building you are trying to heat, just to avoid indoor air quality problems. Thus the gain in efficiency from a standard furnace to the new standard in efficiency was roughly 12%. You could gain that much in efficiency by installing a vent damper and electronic ignition package on an old furnace. Still, we continue to rip perfectly good furnaces out of our homes and throw them away. We have a better solution:
If you look at all the new forced air heating systems that are being introduced today, most of the more efficient ones use something called “burner modulation”. This means the burners will not fire on high all the time. Instead, they will fire at a lower rate during normal use, and only fire on high when it’s very cold outside (when there is a higher call for heat). This is better than the old systems, but still over-fires. For example, the design temperature standard for Denver is 75 degrees. This means when it is 5 below zero outside the system should maintain 70 inside, but no more. If it is capable of maintaining more, according to A.S.H.R.A.E. (American Society of Heating, Refrigeration and Air Conditioning Engineers), the unit is too large, will short cycle, have a decreased lifespan and will not deliver the listed efficiency. So, let’s assume we need 50,000 Btus to keep the building at 70 inside when it’s -5 outside (this is a pretty good average for a 3-bedroom home today). Since standard furnaces are either on or off, and average furnaces have 100,000 BTU inputs, this means the only time they come close to proper sizing is when it’s colder than the design temperature. At normal temperatures like 30 to 40 above zero, when the requirement is only 20,000 to 30,000 BTUs, that furnace is firing as high as 75% more than necessary! So, regardless of how efficient a burner system is, if it’s firing more than 20% higher than the design standard (again according to A.S.H.R.A.E.), the results are extremely high fuel consumption. So the way furnace manufacturers have compensated for that is by employing step-modulating burners and variable speed drives. The variable speed drives (or VSDs as they are called), serve to increase and decrease the fan speed based upon the building’s heating needs. This saves only a small amount of electricity, but does help even the temperatures in the building. So the blower system isn’t where the savings are. The modulating burner system is the best idea so far. However, companies like Rinnai have been making fully modulating burner systems for years. We’ll get into that in a moment. For now, back to Step Modulation:
The new furnaces have a two-step modulation. So, for example, the furnace will come on at 100,000 BTUs (again, as much as 75% higher than needed), but then they will modulate down to a lower setting, usually about half of the high setting. So the burner may run at 50,000 BTUs during the times that the temperature in the building is fairly close to the set point. This means that the furnace will only over-fire by 20 to 30% during normal temperatures, which is within A.S.H.R.A.E. standards. This is better, but still not the best way to save energy.
Let’s take that same old furnace, and instead of replacing it, remove the heat exchanger, gas valve and burners and replace them with a hot water coil, similar to a car radiator. We’ll bring the fan on when heat is needed, along with a pump that will circulate water through a coil and back to a tankless water heater. Here’s where infinite modulation comes into play. The tankless system detects flow and water temperature and modulates the burners to create the exact water temperature required, only using the BTUs needed to maintain that temperature. Instead of a two-step modulation process, however, water heaters like the Rinnai use one BTU modulation increments. This is truly the most precise modulation imaginable, so the system will never overfire! Can you imagine a furnace that modulated that way? The gas valve alone would cost over $1000. The best part of a conversion is that it costs less than half what an equivalent efficiency furnace costs. It’s a real value, especially considering the energy savings and lack of parts that need replacement down the line. Once a furnace has been converted, the only moving part is the fan and motor. No more gas valve, fan limit control, blower relay, combustion fan, pressure switch, control board or heat exchanger to break and cost money. Plus, since the source of heat is a sealed-combustion appliance, the need for additional combustion air is eliminated, meaning the house is tighter and less cold air is introduced, not to mention eliminating the burning of indoor air for combustion. So from and energy efficiency and indoor air quality standpoint, it makes perfect sense to convert your furnace instead of replacing it. It also keeps old furnaces out of the landfills.
Many homeowners are considering solar thermal for home heat, but are faced with a major dilemma: only 5% of homes in Denver have hydronic (hot water) space heat. In order to use solar for space heat, major renovation is usually necessary, making the conversion cost prohibitive. This is the icing on the cake for integrated systems. When a conventional system is installed, there is virtually no way to use solar thermal to provide space heat without expensive renovation. With an integrated system, the water that is used for space heat can come from the tankless water heater, from a boiler, from an efficient water tank, or from the sun! It then makes perfect sense to install panels and a solar tank to create space heat and domestic hot water and further increase efficiency, without having to completely redesign the system. The same hot water coil that is installed in the furnace then acts as a solar thermal heat exchanger!
It has been said many times: “our world must come together or we’ll fall apart”. This saying could not be truer when it comes to energy usage and sustainability. Many people subscribe to the “Z squared” philosophy, which basically tags true sustainability as Zero Waste and Zero Consumption. In order to attain this lofty goal, we must all be more conservative with our resources, and integration is the key to this as regards building mechanical systems. By doing more with less, we have taken the first step toward true sustainability and green living.
Dave Emmitt is the CEO of Direct Drive Service of Boulder Colorado.
www.DirectDriveService.com
