If you’re looking for a new heating system this late in the season, we’re going to guess you might be in a bit of a hurry. Either you’re moving into a new home that doesn’t have one yet, or your current system decided to die on you earlier than you thought it would. One way or the other, it’s important that you know a few things before you rush out and get a new heating system. Knowing how to read heating ratings is important regardless of what type of system you’re looking for.
Annual Fuel Utilization Efficiency
Annual fuel utilization efficiency (AFUE) is the rating governing combustion systems like furnaces and boilers. It’s an average of a system’s efficiency throughout the year, in an attempt to give the most accurate picture of how that system will perform once installed. The way that AFUE is determined is by measuring the amount of fuel put into the system vs. how much heat is gained from it.
This equation used BTU’s (British Thermal Units) for measurement. So, if a system has 100 BTUs of energy put into it, and it generates 60 BTUs, that’s an AFUE of 60%. Which is pretty terrible, honestly. Fortunately, the vast majority of furnaces and boilers on the market today have an AFUE of greater than 75% in most cases. The higher the AFUE rating, the better return you’ll get on your investment in a heating system.
Heating Seasonal Performance Factor
Not all heating systems actually burn fuel to create heat. Air source heat pumps rely totally on refrigerant to absorb preexisting heat and release it inside the home. AFUE obviously does not apply to these systems; they use Heating Seasonal Performance Factor (HSPF) ratings instead. HSPF measures how much heat energy is delivered to a destination compared to the amount of electrical energy expended to do it.
The equation for measuring HSPF is much more complicated than AFUE, so we will only say that the rating is from 1 to 10 with 10 being the highest. Anything equal to, or higher than, 8 is generally considered to be “high efficiency,” though that does not mean that a slightly lower number indicates a wasteful system.
Know Your Ideal Ratings
Even knowing this basic information, it can be quite difficult to find a system with the ideal rating for your needs. Even if you’re not too picky about the difference between an AFUE of 75 and 85, however, you should still have an idea of the impact the rating will have. If you’re not sure whether or not you’re looking at the right heating system for your needs, we highly recommend talking to a professional about it. Better to take your time and get the right system for your home the first time, than to install one that isn’t a good fit and will need to be replaced later.