InspectAPedia ^TM

Return Air Registers & Ducts for Heating / Cooling Systems AirCondAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• Defects in return air ducts & registers for heating or cooling systems
• Return air adequacy
• Air Conditioning (or Heating) Duct Defects

This chapter of "How to Inspect the Central Air Conditioning or Cooling System" describes the inspection of the defects in return air registers & ducts for heating or cooling systems (HVAC) such as missing air conditioning cool air supply or return air registers, undersized air conditioning duct openings, improper cooling duct routing, cooling (or heating) air duct corrosion, leaky air duct connections, defective heating or cooling ductwork materials.

The photograph above shows a single central return air duct located outside of the apartment which the duct system intends to serve. This installation prevents recirculating of air through the air handler for heating or cooling and results in poor air flow and increased heating and cooling costs for the apartment owners.

© Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

The master document, of which this is a chapter, describes the inspection of residential air conditioning systems (A/C systems) to inform home buyers, owners, and home inspectors of common cooling system defects.

Basement Air Handler, No Return Air Ducts, All Return Air Taken at Air Handler

One-Way Cooling or Heating Systems: Some retrofit HVAC installers simply cannot figure out where to place return ducts, so they are just omitted such as shown in the two photographs here. For example a basement or crawl space air handler may be found with no return duct connections at all. Rather you'll see that the return plenum is simply open to the basement or crawl space. The second photograph confirms that wet, possibly moldy debris enters the HVAC system at this single point basement air return to the blower unit. In the foreground of the photograph you can see our Burkard (TM) air sampling machine being used to take a look at what the basement is sending into the home's ductwork and living space.

This forms a "one way" cooling or heating system - 100% of the air is drawn from the area around the air handler, cooled (or heated) and blown "one way" into the occupied space. This is the most inefficient design possible as well as possibly a dangerous one (see "Flue Gases" above).

Preferably return air is drawn from the heated or cooled space. Taking "new" makeup air from an unheated space, heating it, and blowing it "one way" into the heated area has to be a more costly way to heat a building. For better indoor air quality and as recommended by ASHRAE, commercial and large residential heating and cooling systems may include aportion of outdoor fresh air input to the duct system as well.

Attic Air Handler Air Conditioner Return Duct Defects

This photograph shows a typical black, large-diameter return flex-duct moving building air to the air conditioning system air handler unit located in an attic. Notice the loose fiberglass insulation around the base of the large-diameter black flex-duct carrying return air? Poor connections at this location were pulling loose fiberglass insulation fragments and attic dust and debris into the air handler system. In addition, this poor return duct connection, by leaking attic air into the duct system, increased the air conditioning operating cost by feeding it hot attic air instead of building living space air. This photograph has a couple of other interesting details. Notice that the return duct is partly crimped and thus obstructed as it passes through the site-built building truss? Also, what's that electric motor doing lying askew in the insulation next to the flex-duct? Perhaps the central air return, located in the ceiling of the space below, was placed where previously there had been a ceiling-mounted whole house fan, for which we see the motor, abandoned in the attic floor. Understanding the history of changes made to a building can help interpret the meaning of clues about the building condition. It would be a safer practice to remove the still-connected but un-used fan motor. Either remove the un-used fan circuit wiring completely, or enclose the termination of the un-used wires in a junction box.

AIR CONDITIONING SYSTEMS Chapter Index

To continue reading this air conditioning inspection guide, use links to the document chapters at left or below. Links shown in green font indicate where you are in this document.

Technical Reviewers

Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

More Information on Building Diagnostic Inspections and Repairs

InspectAPedia ^TM Home & Site Map - Building Inspection, Diagnosis, & Repair, Environmental Inspection & Testing - Research Website

The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems

Home Inspection Construction Consulting Services & advice for home buyers

Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.

Contact Daniel Friedman for website content suggestions or for fee-paid consulting

	Enter your search termsSubmit search form
	Search This Website - InspectAPedia.com