traditional (non-condensing) vs. Condensing Boilers

 With a traditional (non-condensing) boiler, the exhaust gases are very hot, typically around 400°F. Those hot exhaust gases are immediately sent up a chimney and take a lot of thermal energy with them, which limits the energy efficiency of traditional boilers. 

Less expensive to purchase, install, and maintain. The downside is only that they are less efficient. The EcoPilot Technologies Saver-3 solves this problem. 

 A condensing boiler, on the other hand, has components in the flue system that transfer some of that thermal energy from the hot exhaust to the water that is being heated. In the process of transferring that energy, the exhaust gases cool enough to cause condensation of the water vapor from those gases, hence the name “condensing boiler.” 

 However, this increase in appliance efficiency adds a variety of complications. First, the controls for condensing boilers are more complex. Water returning to the boiler (after heating the house) is used to pull the thermal energy out of the hot gases in a heat exchanger. The temperature of that return water can’t be too high; otherwise, the exchange of heat doesn’t happen properly. Maintaining an optimum return temperature requires more controls than on a traditional boiler. 

 Second, the liquid condensate that is generated in the exhaust heat exchanger needs to be drained off somewhere, which usually requires a reservoir and a pump of some sort  

 Third, the condensate liquid has a pH in the range of 3 to 5 (not as acidic as lemon juice, but more acidic than milk and about the same as tomato juice). That means the exhaust heat exchanger—and anything else the condensate liquid may touch—needs to be chemically resistant to acid. Stainless steel or aluminum-silicon alloys are the materials of choice. Also, because of this high acidity, the exhaust cannot exit through the same masonry chimney that is being used for the existing boiler without an acid-resistant liner. 

Fourth, because the exhaust from a condensing boiler is relatively cool, it’s not particularly buoyant. It doesn’t go up a chimney very easily, like the 400°F exhaust from a traditional boiler does. So the exhaust needs to be pushed out with an exhaust fan.