First of all let’s start by saying that all three areas mentioned; crawl space, attic and garage and all acceptable per code. In talking with Mike Moyer, owner of Moyer’s Heating and Cooling, Mike’s recommendation and thinking is that whenever possible both the system and the ducting should be installed inside the thermal envelope (below the insulation line or above the vapor barrier). This would not be safe with an older open burner gas style appliance, but for the best efficiency Mike suggests that you look for a dedicated mechanical room inside the thermal envelope. Installing the unit in the garage could possible contaminate your home with fumes that would be carried in by the furnace or exposed ducting that was not properly sealed, so sealing is of the utmost importance. Freezing temperatures in both crawl spaces and attics will certainly adversely affect the efficiency and operation of your system.

We also took your question to Steve Voevodsky, owner of Energy Savings Heating & Cooling for comment. Prescott is considered primarily a heating market where we heat 7-8 months vs. cooling 2-4 months of the year. Using that as a guideline, Steve feels that it is important to feed the air from the floor. The duct system should be designed to bring the air flow from the crawl into the home through floor registers. You would have to be cognizant of register placement so ensure that the registers are not covered up with furniture. Another issue Steve said is critical is when feeding air flow from the floor is to make sure that you have adequate return air registers up high enough so that the hot air that does not rise by natural flow and will be pulled back into the system and redistributed. This will give your home a greater comfort level and should be less expensive to operate. The furnace can be installed in the crawl space or placed in a mechanical room. Steve from Energy Savings also feels that attic installations are good for air conditioning the home due to the fact that cold air falls, however, as a reminder the system should be designed for more heating than cooling because the heating season is what we use most.

As a side note, both of these company representatives said that it is critically important when building a new home that the builder and the HVAC Mechanical company consult together to ensure greater efficiency for your system. There are many other components involved such as where the thermal barrier is located, the type of insulation being used, where the mechanical room is located. Your HVAC company is a major player for energy efficiency and should be involved from the beginning of the process.