Heat rises, right? Not necessarily so. In fact, thermodynamic laws simply show that heat moves from higher-temperature to lower-temperature environments. In large part, though, the old physics class credo does hold true. It may not have been too interesting at age 11, but its implications become far more important when we grow up, become homeowners and find both hot and cold spots make parts of the house uninhabitable.
The basic problem
Uneven temperatures can make both homes and offices very uncomfortable. When air stratifies – forms layers – on a floor-by-floor basis, the upper floors can be sweltering, while a visit to the basement chills the hardiest of hearts.
Occupants of the lower floors ramp up the thermostat, the furnace supplies heat to the occupied spaces, which immediately migrates upward through any open areas. Those upstairs get even hotter, while the basement remains frigid. Spending money on making things worse for everyone isn’t good, so understanding and dealing with the issue is important.
We call it stacking
Heated air is lighter than cold air; it has an inherently lighter density, which is why it “floats” upward. For the same reason, more dense colder air sinks. Areas divided by floors tend to stratify, holding on to air pockets according to density – for which read temperature – and this, in simple terms, is why most basements are colder than most upper-floor bedrooms, even in well heated houses.
The phenomena is called “stacking,” or “the stack effect,” in industry-speak.
Aside from the scenario suggested above, this is bad for both budget and environmental impact in another way: when your home is effectively acting as a giant chimney (or stack, coincidentally), the upward-moving air has to go somewhere. It leaks out through unintentional gaps and around deliberate penetrations in your attic, so you are, in a very real sense, paying to heat the outside air.
Your easy solutions
Multi-level heat disparity, in both homes and commercial buildings, is typically the result of ineffective HVAC installation. The problems include, but are not limited to:
- Duct Design. Numerous structural factors impact the size, style and routing of ducts, and the placement of registers (vents). Specialist training is necessary to predict and design answers to impediments such as frictional losses, ensuring that both quantity and velocity of treated air is adequate to all areas.
- Inadequately sized equipment. Both too-large and too-small furnaces and air conditioners can cause problems; the former cycle on and off too rapidly for the building to even out, and the latter struggle to do any good at all (that struggle often causes premature component failure, also)
With today’s improved insulation, old rule-of-thumb formulas for sizing equipment are outdated and irrelevant.
Air Conditioning Contractors of America, or ACCA, is the USA’s largest organization serving HVAC contractors. There, ducting must be installed according to ACCA Manual D standards; equipment sizing to ACCA Manual J standards. In Canada, the largest organization serving HVAC contractors is the Heating, Refrigeration and Air Conditioning Institute of Canada, or HRAI. HRAI’s equivalent to Manual D is the Load and Duct Manual; HRAI’s equivalent to Manual J is CSA F280.
The proper sizing of equipment can be carried out in Canada using either set of parameters, and all ClimateCare technicians are fully trained in their use. Without these skills, and constantly updated education and testing, the homeowner has no guarantee their system will provide the precise amount of air movement that’s necessary to ensure your Ontario home comfort systems work. Find your local ClimateCare member today!
