1 ton of cooling is equal to 400 cubic feet of air per minute. 2 ton of cooling is 800 cfm and so on. So a 4 ton unit will have
1600 cubic feet of
air passing through the system every minute.
How big of a return does a 4 ton unit need?
1 ton of cooling is equal to 400 cubic feet of air per minute. 2 ton of cooling is 800 cfm and so on. So a 4 ton unit will have
1600 cubic feet of
air passing through the system every minute.
How big should my AC return be?
A return air grill should be sized
for an air speed of 300-500 FPM(feet per minute)
. 400 FPM is the median air speed for this calculation. We are after the ability to move 980CFM so you now divide this number by 400 FPM yielding 2.45 or 2.5.
How much return air do I need per ton?
Since the conventional wisdom of designing return grilles at
144 sq.in. per ton
is so widely accepted, the average system return is undersized by 30% or more.
How much return air do I need?
Generally, if you are using a Duct Sizing Chart or calculator (such as the Trane Ductulator), size the re- turn ducts for 0.05 inches/100 ft (0.40 Pa/m) based on the expected airflow through that return air duct. The total sum of air from all the returns should be
at least 250 CFM/nominal ton (33 l/s per-kW)
.
What size ductwork do I need for a 3 ton unit?
Multiply the tonnage, 3.5, by the total BTU per ton and this will give you the total BTU rating. Multiply 6 x 42 to determine the duct size of
252 square inches
The clear are of the duct must be at least 252 square inches This measurement also includes the opening in the floor at the bottom of the return.
Can a return air duct be too big?
Can an air return be too big? No,
an air return cannot be too big
, except in extreme cases where a closed room is temporarily under negative air pressure. Return vents maintain air pressure, filter out debris, and are critical to the efficient operation of any HVAC system.
What happens if there is not enough return air?
If there is not enough return air available,
your HVAC system will not heat or cool properly
. … If not enough air is brought back, your HVAC system will not be able to keep up with temperature demands. In some cases, two returns may be necessary to provide enough return air.
How do you size a return air duct?
Calculate
the square root of the total
. (Example: 4 (ton unit) x 144 square inches = 576 squared. The square root of 576 is 24. Therefore, your return air duct and grill size will be 24 by 24 inches.)
What happens if return air is undersized?
If the return duct is too small, there are an inadequate number of return grilles or they are undersized,
it can't return enough air to recirculate back into the system
. This poor airflow not only makes your system run longer than necessary to provide comfort, but increases your energy bill as well.
How many CFM can a 12 inch duct handle?
The rule of thumb for a 12 inch duct is
715 cfm
. You would need a 20 inch duct to handle 2000 cfm.
How many CFM is a 5 ton unit?
The rule of thumb about air conditioning was quoted in our opening statement. The basis for rating self-contained air conditioners is usually this value. We have a 2-ton unit handling 800 CFM, a 3-ton 1,200, a 5-ton
2,000
, and a 10-ton 4,000.
How many CFM can a 4 duct handle?
What is the minimum duct size for a range hood? The minimum duct size for a range hood is 4”, which is ideal for range hoods
400 CFM and under
.
Can you have too much return air?
Having several return vents (ideally one in every room, but even two or three is better than just one) creates consistent air pressure. If you have one return vent, your home is fine. Keep the doors to each room open so air can properly circulate.
Why does my AC return whistle?
In most cases, a high-pitched whistling sound means that
your air conditioner isn't getting enough airflow through the return vents and ductwork
: the ones that pull air from your home to the air conditioning evaporator coils to cool it. Your air conditioner has to work harder to pull enough air through the system.
How do you increase return air flow?
- Check Vents and Registers. One of the simplest things you can do to increase airflow in your home is to check the vents and registers in each room. …
- Turn on Ceiling Fans. …
- Schedule HVAC Maintenance. …
- Consider Duct Cleaning. …
- Invest in a Ventilator.
