Air Flow Diagnostics
For every 1 or 2 quality Heating and Air Conditioning Systems being installed, there are 8 or 9 Systems installed without regard to Real Life Energy Performance. Do you think it’s easy for the Reputable HVAC Contractors out there that can compete with the cheap guys? It’s rather difficult. But now that energy costs are on the rise, the Air Flow Diagnostics will eventually become a normally discussed issue in the contract between the HVAC Contractor and the Builder/Home Owner.
Even though Building Codes specify minimum standards for a HVAC Duct System, the Local Building Codes generally are not enforced. When they are, there generally isn’t an independent verification process in place (unless of course the building designer or the architect has required this in the scope of work). The EPA claims that as much as 30% of the Conditioned Air is lost through Poor Duct Construction and Air Duct Installation. Here is some advice: for anyone building a new home/business or considering a new HVAC System, consider investing more money in the Air Duct System to avoid future heartaches.
Typically, an Air Duct System should last the life of the home. The Gas Furnace and Air Conditioning System most certainly will not. Would it not make sense to invest a little more in the Air Duct System that will soon be buried in the hard-to-reach parts of the house forever? If you’re interviewing HVAC Contractors and getting estimates ask your HVAC Contractor, how much would it cost me for a High Quality Air Duct System, one that you can verify is 90% or more air tight? You may get a variety of responses and even a blank look on occasion. Do you see what you just did? You’re asking for System Performance (to be documented), and you’re wondering if you’re getting their highest quality from the get-go. It may be awkward if the HVAC Contractor comes back with a yes, we can design and build a High Performance Air Duct System. You may wonder why they didn’t offer it to begin with. I know I would be disappointed if I knew the HVAC Contractor I was about to hire gave me a price for their “B” system I want to have the option for the very best; at least to consider it anyway.
A typical Heating & Air Conditioning System is designed to move 400 cubic feet of air per minute per 12,000 BTUs (which simply means 400 CFM per ton). The HVAC System will work just fine if it’s a little below 400 CFM/TON, but let us stick to practical examples for now. The HVAC System will have to move a lot of air. Here is the formula:
Sensible Load in BTUH = CFM x ∆T (change in temperature) x 1.08.
So, to summarize, if there is a lack of air flow (improper design, restrictive ducts, High Static Pressure), a Leaky Air Duct System, Dirty Refrigeration Coils, an Improper Refrigerant Charge, or lacking Duct Insulation in unconditioned areas, you simply won’t have the same BTU delivery to your home. In other words, you need to perform an Air Flow Diagnostics. The disadvantage is you’re still paying the electric company the same money for less Air Conditioning and Heating. If the Air Duct System and Refrigerant Charge is really off the beaten path, you’ll sadly pay much more money for less cooling. Your response may be: The house stays warm in the winter; what’s all the fuss with this Static Pressure Measurement stuff?
Well, if you don’t mind not knowing how much energy you’re wasting, then let’s drop the subject of Air Flow Diagnostics. However, with today’s bigger homes and energy prices reaching new records every year, we at US Air Contractors Heating & Air Conditioning, have a hunch there will be some folks out there who will be requesting performance clauses in their contract agreements with the building contractor, or the HVAC Installers if the owner is hiring the sub contractors direct.