Efficiency

A high efficiency furnace or boiler will heat your home with less fuel and low emissions, thereby cutting the cost of fuel as well as maintenance. The estimated efficiency of a heating unit can usually be found on the label, listed as the AFUE (Annual Fuel Use Efficiency). This number can give you an idea of where to start with efficiency, but is unfortunately fairly inaccurate. Due to not accounting for "Idle Loss", systems with identical AFUE ratings can differ in performance by as much as 25%.

There are also several more industry-specific efficiency numbers that are used by manufacturers, such as ASME testing (in the US) and the European EN 303-5 testing standard for wood boilers. These can offer a bit more accurate comparison, but they have their own issues. In fact, the ASME test is being retooled this year for better accuracy, which may cause a lot of efficiency numbers to change.

When comparing different makes and model of furnaces, the ASME efficiency value is the most consistent. However, know that it is not an iron-clad comparison and real-world values may vary by a wide margin.

Heat Load || Sizing Your Furnace or Boiler

Heat load is the amount of heat needed to maintain a desired temperature. A heat load measurement will help define the most efficient size of furnace or boiler for your needs.

It may be tempting to say "bigger is better", but an improperly sized heating unit will cause you plenty of grief. If the output of your heating unit is too high, it will not run at full capacity. Heating below capacity will cause your efficiency to drop, emissions (including creosote) to increase, and may cause maintenance issues in the future. If your unit's output is too low, you will not be able to meet your heating needs.

Heat Load calculators can provide you with a fairly accurate measurement for the BTU output your heating unit. Keep in mind, these calculators run on mathematical formulas. They can provide good estimates, but the results are not an exact scientific measurement. Unless you are heating inside a vacuum, you will be constantly gaining and losing heat. This is because there are so many variables involved. Things like dormers, elevation, and the number of windows are only a few examples in the mountain of variables that effect this constant change.

When replacing a system, a Heat Load calculator is a great place to start. You can save a lot of time and effort by maximizing your efficiency and savings by knowing your heat load. If you so desire, an energy auditor or qualified contractor should be able to help you calculate this measurement for you.

Start saving money by maximizing your heating efficiency right now by going to:  http://www.shophmac.com/info-center/hvac-calculators/heat-load-calculator.php