What is all this talk about BTU input, BTU output, Thermal Efficiency, Overall Efficiency and Combustion Efficiency?

Since the beginning of time boys in particular have waged a war on “mine is better than yours” or “my fish is this big”, and the story got bigger as the day went on. The same is true of Wood burning and may I dare say Corn/Wood Pellet Flex-fuel appliances.

I remember back in 1979 when heating capacity first hit the marketing scene. Some manufacturers would take wood logs, cut them into little itsy bitsy pieces and then stuff the wood stove, furnace or fireplace with as much wood as possible, slam the door shut (a little kick would help) and then take it out, weigh it and proudly announce to the world that their unit had this huge BTU (British Thermal Units, or in layman’s terms heat output) capacity and was better than the next guy. The manufacturer that was trying to make an “honest” living would publish the BTU output capacity knowing that the inefficiency of the appliance would reduce the input capacity. Less than desirable dealers and manufacturers would tout the BTU input and say that the appliance was capable of heating a larger home, etc. etc.

The same would hold true of how efficient their appliance was and the deception continues (maybe a modern day soap opera called “how the wood burns’ is in order).

American Energy Systems Inc., manufacturer of the world renowned MagnuM and Country Flame product line would like to set the record straight on how to understand which unit is capable and efficient to heat your home and place all appliances on the same level field. This is going to be really exciting.

BTU INPUT: This is the amount of heat that the appliance is capable of producing on any given heat setting (if published for multiple settings) or the total heat capacity (this is normally what is done) when the appliance is on its highest setting. Some manufacturers list the minimum heat capacity and the highest heat capacity to give you a range. If it is not printed on the owner’s manual or on the testing label (this is required and must have either BTU input or output listed) then be sure to ask the reseller which he is stating.

BTU OUTPUT: This is the amount of heat that the appliance is capable of exiting into your home after all deductions for fuel moisture, unit heat exchanger design and exhaust temperatures are taken into considerations. It is very rare that a manufacturer or a reseller of the product will publish this because it is hard to determine with so many factors such as fuel quality, installation, venting and maintenance habits. Normally when a “pinstriped” salesperson is touting their unit will produce this much heat they are talking about the BTU input and not the actual output of the appliance. Make sure that you clarify with the person what they are talking about.

THERMAL or HEAT TRANSFER EFFICIENCY: This is where the “rubber meets the road” in a heating appliance. Thermal or Heat Transfer Efficiency is the ability of the appliance to transfer the heat from inside of the appliance directly into your home. This is usually the lowest number on the efficiency scale and very rare is it ever published because there are numerous factors that apply and will change depending on installation, operation, maintenance and home environment. Probably not wise to ask the salesman what this is because we do not want to make him or her feel bad when they have that deer in the headlight look. Typically only the manufacturer will know this information and rarely will release it.

OVERALL EFFICIENCY: This is the average efficiency that an appliance will perform at. Most reputable manufacturers will list this efficiency and identify that it is overall efficiency. It is important to remember that when a manufacturer has to increase the air to a appliance to get it to burn poor quality fuel that the overall efficiency suffers as a result and that means you will burn more fuel, heat less area and have considerably more maintenance.

COMBUSTION EFFICIENCY: This is the efficiency that the fire itself is burning at right at the combustion source. Unfortunately some manufacturers and sales people will tout this efficiency to claim that their appliance is better than another to get you to purchase theirs. You need to show them just how intelligent you are and tell them that taking into consideration fuel quality, fuel moisture, venting configuration, operational and maintenance habits, etc. etc. that there is no way that their appliance can have a overall efficiency of 97 plus percentage.

Here is a typical example of a well designed appliance and how the efficiencies break out:

• Combustion efficiency = 98%
• Overall efficiency = 83%
• Thermal or heat transfer efficiency = 76%

Now you have a well represented, well built appliance that will heat your home.

I know that you are totally excited now from all of this information and ready to try out your new found skills. First step is to research the best product on the market, compare it to other units on the market and then make a intelligent decision. Do not fall for salespeople that rip down other products. That just means that they do not have the same information that you will have and maybe are a little intimidated by other manufacturers products.

American Energy Systems set the standard in quality products for your home, and we like to tout our honesty and integrity in selling, not rip down someone else. We will continue to help you and answer questions. Do you have a question you’d like answered? Give us a call!