Save Energy — Heating Systems

Perhaps one of the first uses of a home was to keep warm during cold winter days. In today’s home you can be warm enough to wear a short sleeve shirt even on the coldest nights. All of this is accomplished with some means of heating. Whatever the type of heating system, energy is needed. As days get colder then that energy increases.

Your Home Energy Living Plan

  • Set thermostat at lowest comfortable temperature. Setback the temperature at night if possible. See thermostat.
  • Take actions to reduce air leaking through cracks, reduce infiltration of cold air.
  • Cover windows at night and open shades when the sun is shining.
  • If you have a heat pump, do not turn on the emergency or standby heat.
  • Consider efficiency when buying a new furnace or heat pump.
Impact of Your Energy Saving Actions

About 35% of the average US home’s annual utility bill is for heating. This can vary depending on where in the country you live. In the north this percentage can be much higher. Heating is a major chunk of your utility costs. Actions to reduce heat loss, like reduce infiltration and improve insulation, will have a major impact. If you have an old furnace or boiler, replacing with a higher efficiency unit will save a significant amount of energy.

How Energy is Lost

Heat is loss from your home to the outside on cold days and nights. Your heating system must replace the heat loss.

Characteristics of Heating Systems

Heating is by the combustion of a fuel, usually natural gas, but can be propane or fuel oil in an appliance called a furnace. It is the heat generated from the combustion that is used. However, it can not be directly used because it contains toxic gasses. A heat exchanger in the furnace is used to transfer the heat from the flue gasses to air that can be circulated throughout your home. Energy is lost in this transfer; so this type of heating can never be 100% efficient. However, much progress has been achieved in furnace efficiency. Old furnaces were 70% efficient with this percent dropping with age. Old furnaces operating at 50% are not uncommon.

The problem with combusting fuel is that the combustion products must be kept above the boiling point of water. The major product of combustion is water vapor. If this vapor condenses in the flue, then corrosion can take place. Other products like nitrogen and sulphur can combine with oxygen. If it condenses with the water an acid forms. To prevent this, flue gasses are kept well above 212 degrees (condensing temperature of water), usually around 300 degrees. This is a lot of heat to escape up the flue or chimney. Modern furnaces are capable of efficiencies in the upper 80% without condensing water out of the flue gasses. To further improve efficiency, some furnaces allow the condensing of flue gasses. These furnaces are more expensive because they have an additional corrosion resistant heat exchanger. The condensed gasses are allowed to flow down the drain.

Some homes may use hot water or steam for heating. Instead of a furnace, a boiler is used to generated the hot water or steam. Boiler efficiency is similar to a furnace. There are boilers that can condense the flue gasses for the highest efficiency possible.

Another method of heating is the heat pump. A heat pump uses the refrigeration cycle used in air conditioning only in reverse. In the summer your air conditioner (or heat pump) collects the heat from within your home and discharges it outside. A heat pump in the winter collects heat from the outside air and discharges it inside. (Air has energy as long as it is above absolute zero.) The energy used by a heat pump is for operating the compressor and fans, and is not the heat moved. Therefore a heat pump can move more energy than used. A heat pump will use much less energy than a furnace or boiler. However, they use electricity that is much more expensive per Btu.

Heat pumps have been popular in areas with extremely mild winters. Since they also cool, their main use is cooling but can heat when needed without another piece of equipment. Their drawback is they lose heating capacity and efficiency as the outside air gets cold. In colder climates some sort of extra heat is needed. This is usually by electric resistance heater.

Due to rising costs of natural gas and discounts by electric utilities, the use of heat pumps is moving further north. Heat pumps can be found throughout the midwest and central parts of the country.

Another method growing in popularity is radiant heating, usually in the floor. Generating the hot water to flow through the tubes is generally same efficiency as heating air. However, the radiant contribution from a heated floor will allow a lower temperature in your home.

Energy Solutions Explained

Lowering the thermostat reduces the amount of heat needed to maintain comfort. Try reducing the thermostat a degree at a time, in order to find your lowest comfortable temperature. Setting back your temperature at night and when not at home can save energy.

Take actions to reduce infiltration and increase insulation. If air blowing in a crack can be felt, it seems colder than the actual temperature. As a result the temperature on the thermostat is increased. Not only are you losing heat through the crack, but also running the furnace longer.

Windows and other glass surfaces will be colder than the temperature in the home. You will lose radiant heat through the windows. This makes you feel colder. Covering the window at night block the radiant transfer. You feel warmer without raising the thermostat.

Do not turn on emergency or auxiliary heat of a heat pump. As it gets cold outside a temperature will be reached when the heat pump compressor can no longer meet the heating load. Another auxiliary heat method (electric resistance) is automatically activated. The system is designed to do this as efficiently as possible. If your turn on the auxiliary heat to soon, energy will be wasted.

Once as much can be done to reduce the heat loss of your home, then you can consider upgrading your heating system. Heating systems have increased greatly in efficiency.

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