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NORA Advanced Efficiency

National Oilheat Research Alliance 27 boilers that do not thermally purge. Although thermal purge is very efficient with new equipment, it may not be right for many existing boilers. Cast iron and higher water volume steel boilers may cause excessive heating during thermal purge operations. Also, some boilers are not designed to sit cold during idle periods, which may result in leaking gaskets and the possibility of thermal shock. Automatic/Manual Thermostat Set-Back The thermostat is the single best device homeowners can use for energy conservation because the temperature the rooms are heated to has a big effect on how much energy is needed. The greater the difference between the inside and outside temperatures, the greater the heat loss. Living with slightly lower thermostat settings can reduce energy use. For every degree the thermostat setting is lowered over a 24 hour period, the heating bill drops by as much as 3%! Routinely setting the thermostat lower once or twice a day when additional heat is not needed because no one is in the building or everyone is in bed can save significant money. When temperatures outside are very cold, a setback may lead to the system being off for too long. In that period, some of the radiator pipes in outside walls may freeze, which could lead to water damage or the house getting too cold. Set-back thermostats should not be used on radiant heat, steam heat or hot water systems with large radiators. It works best on furnaces, hydro-air systems, and fin-tube baseboard. Thermostat set back can be accomplished manually or automatically. The new digital set back thermostats are very reliable and easy to use. Condensing Boilers and Furnaces Venting large amounts of exhaust gases results in significant loss of energy as the steam in those gases has absorbed a great deal of energy. To recapture this energy and use it in the home, manufacturers have developed condensing appliances. These units have larger heat exchangers. The heat exchangers cool the combustion gases down to the point that the steam in the combustion gases condenses back into water vapor and then into water, thereby returning this latent heat to the heat exchanger. For the water in the boiler to condense; the water from the radiator pipes must be below 120°F, Figure 1. When considering whether a condensing boiler will work in a home (Figure 2 on following page), ensure that these low water temperatures will provide sufficient heat. Combining Efficiency Improvement Options Many equipment upgrade and replacement options are available, and many of them solve the same problem. In assessing savings from multiple improvements, it is important to understand savings cannot be determined by simply adding to- Figure 1


NORA Advanced Efficiency
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