Delivering Cool Air
The furnace ducts use to blow hot air during cold months are also used for the air conditioning system.
If Ducts Are Installed
Have your ductwork inspected. Modifications are often necessary to accommodate a larger volume of cool air coming from the AC system. Older duct systems, unfortunately, are often bigger. Thus, they work better when trying to retrofit the central AC system. Today, ductwork tends to be smaller as the HVAC industry learns more and more about airflow dynamics, as well as the sizing of delivery systems and furnaces.
Following are the usual modifications necessary for existing ducts:
Upsizing the Furnace Blower – The blower size is rated in cfm or cubic feet/minute. By upsizing the blower, you adjust the cubic footage of cool air necessary for your home. An undersized blower will move insufficient air through the coils. The can then freeze.
Sealing the Ducts to Improve Efficiency – The sealing job is best left to pros. This is because an imbalance in the system can trigger hazardous back-drafting during heating season or warm air pockets during the colder months.
Replacing Old Supply Registers – Swapping the older registers for new ones will allow a bigger air volume to pass. Grilles of old registers with only ¼” wide slits offer extreme resistance to airflow. On the other hand, new grilles can help improve the flow of air by around 15% to 25%.
Ducts that feed cooled air from the attic-installed fan and coil system often wind up in the ceilings of rooms in the first and second floors.
If New Ducts Are Necessary
Because the HVAC’s fan and coil system is attic-mounted in many retrofit AC systems, it can be difficult for supply and return ductwork to reach ceiling registers in the rooms below (first and second floor). Ducts feeding the rooms in the second floor often run through the attic floor then dive in-between the floor joists. This is where they are linked to the ceiling registers. Ducts feeding the rooms in the first floor usually run down through the closets in the second floor.
Your contractor will first determine the ducts’ position to come up with the floor plan for the second floor. It will then be laid over the first floor’s floor plan. Second floor closets often provide access to the locations of the ceiling registers in the first floor.
Ductwork that run in closets doesn’t take up a lot of space. Since ducts are often either 12×6” or 10×8” even in a cramped 2×4’ closet, they use up only 4 out of the total 64 cu. ft.
There are cooling contractors who will recommend using an inexpensive and small flexible hose called a flex duct. However, you should avoid using the material in active closet spaces. This is because it can’t handle normal wear and tear, and it is prone to getting punctured.
How messy can duct installation be? In general, ceiling and wall surfaces are barely touched. No holes in the ceilings in the first and second floors are necessary to accommodate the registers, although some closet floors in the second floor may require a bit of work for the installation of new ducts. However, these holes are small, and will barely create some mess.
With or without ductwork installed in your home, you need to contact a reliable HVAC contractor if you think a central AC system will make your home more pleasant to stay in during summer. The contractor will then assess the cost of installing a central air conditioning system as well as the methods to use.
By selecting the right contractor and equipment, you will help ensure comfortable conditions in your home for years to come.