2019 Idaho Real Estate Blog

HVAC air Flow-True flow readings for air flow through furnace and heat pumps Main The Durable Green Home
Correct air flow through your HVAC system? do you know what your problems are with your heating and cooling equipment? do you know if you have the correct air flow through the furnace and across the coils for the HVAC equipment to operate correctly? We tested several furnaces last week in Boise to see what the air flows were, the results were very awakening.

So how do you test air flow through a furnace? On Point LLC has started using true flow plates to test air flow to determine proper CFM in a HVAC system. I have to admit that I knew air flow was important (thus the many blogs on sealing the ducts system and proper installation) but I  had no idea how important, or  what the true results are in a system. We tested three different systems last week, all energy star homes, so a person would assume (we all know what that means) that the air flow should be pretty close to the recommended air flow. how would you know  what the air flow is? it should be 400 cfm per tonnage of cooling  of the outside compressor unit. so in a 3  ton system that would mean that 1200 cfm would be ideal, and down to 350 cfm per ton  would still be fine. 325 and lower, you have a problem, especially in a heat pump application ( I won't go into all the details).

Out of the three homes, one was 366/ton, one 340/ ton, and one was under 300/ton. why? these were systems that were inspected for kinked ducts, tested under 3% leakage (industry standard is over 30%) tight filter and furnace cabinets. so what effected the air flow? the many things that effect air flow are, kinked  ducts, small ducts, not  using radius  turns  in the duct work, dirty filters, or poor filters for air flow, leaky ducts systems and equipment, poor duct design, and the big one Dirty coils. If  you have a service plan with your HVAC company you should make sure that they are cleaning the filters, and CLEANING THE COILS. make sure this  is getting done, in some states they actually take the coils out (the correct way to do this) and wash them off and then re-install them. does this take longer?YES, but this  is the way it should be done. you might also request a true flow reading of cfm though the system if they can provide this? This test will become a regular part of our companies testing on existing homes to help us better determine problems  and solutions with clients HVAC systems. technology can be a great tool-now if  I can just figure out my new phone!!!

 What should you look for in a system tune up or installation? make sure the HVAC system is set on high fan speed, coils  are cleaned, proper filter, the system has been charged correctly and tested, tight sealed duct system, filter grills cause greater resistance on system limiting air flow, install a clean filter or filter maintenance  program, look for the companies that have service reps with the correct tools. Just like a car, if you don't maintain your home correctly, don't wine  when the systems fail. I am sure  there will be more to come on this issue as we move forward testing homes, i am excited to see the results of a good number of homes being tested.  

 
Posted by Tad Duby at 8/12/2007 5:58:00 PM
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Michelle Penick, Build Idaho Client Real Estate Services

Michelle Penick

Client Care Team
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