Tag: Air Conditioning

Bigger is not always better!

Did you know that there is a protocol to follow when determining the size of your HVAC system? Developed by engineers in the heating and air conditioning industry and adopted by Air Conditioning Contractors of America (ACCA), Manual J has become the standard for ensuring the selection of accurately sized heating and air-conditioning equipment thru heat and cooling load calculations. This process not only ensures compliance with building codes but it also creates efficiency for homeowners.

There are three main reasons why it is important to select the correct HVAC system:

Efficiency: Resources are scarce and energy consumption can be very expensive. Purchasing an HVAC unit that is larger than needed is more expensive to operate for multiple reasons. With oversized units, the space will be cooled faster causing the system to turn on and off continuously, also known as short-cycling. Short-cycling will damage the air conditioning unit causing unnecessary wear and tear. Also, these units consume the most amount of power when the compress is first turning on and to achieve efficiency it needs to be running for at least 10 minutes or more prior to shutting down again.

Comfort: When air conditioning units are larger in size than what’s needed, the system will quickly cool down the air in the home, triggering the thermostat to its desired temperature causing it to shut off the system quickly and without allowing the proper time needed for condensation (typically 10 minutes is what’s needed), which is the process of cooling down the air conditioning coils to dehumidify the air in the home.

Air Quality: With a larger air conditioning unit than needed, the humidity was not able to correctly be removed causing too much moisture within the air. This humidity in the air typically causes mold or mildew in low air flow areas and bad odor within the space.

How do you prevent from having an oversized air conditioning unit installed? Here is how:

During an ACCA approved Manual J load calculation, Rapid Duct Testing’s team of licensed professionals will not only provide the heating and cooling load for the entire space, also known as a block load, but a calculation based on each room known as a Room-by-Room calculation. In designing heating and cooling for a residential home, it is important to consider how the heating and cooling will be distributed throughout the entire home in proportion to each room and its specs.

In a complete load calculation, not only are the apparent areas such as the orientation of all walls, ceilings, floors, appliances and glass considered by our team, but also the building materials that were used during the construction of the home such as roofing and windows. These calculations are then combined with the load calculations of other components of the home like piping and ducts to determine the total load and in turn the correct size air conditioning unit needed for the space in question.



What is HERS testing?
HERS Testing, also known as a Home Energy Rating System test, originated from the HERS program which was created to measure the efficiency of whole house energy components.

Who needs HERS Testing?
The California Energy Commission mandates that newly constructed residential and non-residential buildings have HERS testing to comply with local permits. HERS testing also applies to existing buildings such as installation of a new home HVAC system. HERS can be triggered by a new furnace, new or altered duct system, new AC condenser or refrigerant containing component, new ductless or ducted mini split system.

Why HERS Testing?
The purpose of HERS Testing is to ascertain the energy performance of a building and verify that it complies with current regulations. These tests examine the energy efficiency of the heater, AC condenser, air ducts, duct insulation, HVAC damper, and more. HERS Testing also ensures optimal air quality for the comfort, health and safety of the people who occupy that space, plus indicates opportunities to help reduce energy costs.

How is a HERS Rating Determined?
An air conditioning and heating contractor, general contractor, builder or homeowner enlists a certified HERS rater, like Rapid Duct Testing, to render several diagnostic tests, known as HERS testing. Once these tests are completed the technician will be able to determine a HERS report with the data collected.

The primary tests that comprise HERS Testing, include the blower door test (whole house test) and duct leakage test (duct blaster test).

The WHOLE HOUSE test involves a high-powered fan, called a blower door, that draws air from inside the house to the outside or vice versa. This creates a pressure differential between the home and the outside which determines air leakage. Acceptable air leakage will then be determined by the size of the home or the equipment.

Performing a smoke test for duct leakage enhances this process. Should excess leakage be discovered, corrections to the air duct sealing will be required and the process of pumping smoke (theatrical fog) into the duct system will allow the contractor to identify leakage. Additional tests that may be performed include an EER/SEER verification, fan efficacy test (fan watt draw), minimum air flow measurement, refrigerant charge verification test, etc. With each test that passes, a corresponding form is issued.

Due to the different allowances for new buildings versus HVAC modifications or replacements in older buildings, it is vital to find a HERS rater that stays up-to-date on current regulations