Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
Ask a Question or Search InspectAPedia
InspectAPedia ® Home
AIR CONDITIONING & HEAT PUMP SYSTEMS
BACKDRAFTING HEATING EQUIPMENT
BACKUP HEAT for HEAT PUMPS
BANGING HEATING PIPES RADIATORS
BLOWER FAN OPERATION & TESTING
BOOKSTORE - InspectAPedia
BTU USAGE MONITORS
CARBON MONOXIDE - CO
CIRCULATOR PUMPS & RELAYS
DIAGNOSE & FIX AIR CONDITIONER / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT REGULATORS, DAMPERS, BOOSTERS
DUCT SYSTEM & DUCT DEFECTS
ELECTRIC HEAT, DIAGNOSIS, REPAIR
ELECTRIC MOTOR DIAGNOSTIC GUIDE
FAN, AIR HANDLER BLOWER UNIT
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
GAS BURNER Flame & Noise Defects
GAS PIPING, VALVES, CONTROLS
GEOTHERMAL HEATING SYSTEMS
HEAT PUMPS, DIAGNOSIS, REPAIR
HEATING COST SAVINGS METHODS
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
LP & Natural Gas Safety Hazards
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
MOTOR OVERLOAD RESET SWITCH
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL FILTERS on HEATING EQUIPMENT
OIL ODORS, LEAKY OIL TANK PIPING
OIL SPILL CLEANUP / PREVENTION
PLASTIC HEATER VENT
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
Reset Switch - Heater Primary Control
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS, Chimneys, Vents, Heaters
SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: Heating System Videos
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
Undersized return air duct problem diagnosis & cure: this HVAC ductwork article describes the problem undersized return air openings - a problem that can be observed during inspection of the defects in return air ducts for heating or cooling systems (HVAC). We also discuss duct troubles such as 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 small HVAC return air duct located on an interior building wall. Whether or not this return air duct is adequate depends on how many such returns were installed in the building and whether or not the return air capacity is balanced with the air handler and air supply ducting.
Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman.
When we see amateur attempts to add supply or return air to a system, such as observation of unanticipated openings in building walls, rough-sawn door undercuts, additional openings cut in the return duct or plenum near the air handler, we suspect system design problems. It is possible that previous occupants have found that the warm air supply was not adequate.
Should you confirm problems with inadequate heat delivery in some areas you'll want to consult with an HVAC engineer to make accurate measurements.
Door undercuts, central cool air return: If room doors are shut and not under-cut to permit air flow out of the room, the system's ability to cool the room may be reduced, sometimes significantly.
Try running the cooling system for 10 minutes with all room doors shut. Then open a room door slightly and see what happens!
When a building uses a central return air grille and doors are not undercut heating some rooms may be difficult - system cannot push cold air from the cooled or heated room back to the furnace.
While modest amounts of new duct work (to take return air from the living area) are usually not costly, extensive re-ducting of air flow may involve significant expense
Frequently Asked Questions (FAQs) about about air conditioning, heating, and heat pump ductwork return air registers and duct connections
Question: is our heat pump return register too small? What about noisy heat pump operation?
We recently had installed an American Standard 2 ton 14 seer heat pump in an 1,100 sq ft basement. The basement is now finished but I continually questioned the installer on the size of the return.
The unit is multi-staged and when it ramps up the return is very loud. He installed a 14 by 20 inch return because it fit neatly between the studs. He used 8 ft of round flexible ducting to the air handler.
He also suggested I use the cheap thin filters for lower sound levels and better air flow. There is also a place for a 20 by 20 inch filter at the air handler which he said could be used instead of a filter at the wall return.
Could you please let me know how large the return should be and any pointers on filter use. - D.K.
Reply: Return duct eyeballing and guesstimating
A competent onsite inspection by an HVAC expert usually finds additional clues that help accurately diagnose a problem or could certainly make a more accurate statement about the needed return air inlet and duct layout. And I don't want to get too far into speculation by second guessing your installer since I don't know enough. That said, here are some things to consider:
Noise: I'm not sure what noise you are describing; if it's airflow it could be related to the return and return duct
Questions & answers about too-small or blocked or undersized air conditioning, heating, and heat pump ductwork return air registers and duct connections
Ask a Question or Enter Search Terms in the InspectApedia search box just below.
Technical Reviewers & References
Related Topics, found near the top of this page suggest articles closely related to this one.