Our HVAC Duct Service Gives a Heat Pump a Chance to Breathe in Jonesborough, TN

An existing customer on Old Jonesborough Road in Jonesborough, TN reached out to us and asked us to enlarge their return ductwork in the attic based on our previous recommendation with our HVAC Duct Service. On a previous visit we noticed that their 3.5 ton heat pump did not have enough return air going to it, which was causing adverse operating conditions in the cooling and heating modes. Based on the system's total external static pressure (TESP), it was not moving enough air through the ductwork in order to operate the system within it's design parameters. Operating a heat pump without enough airflow can cause adverse issues within the home, increase monthly operating costs, and drastically shorten the lifespan of the system which leads to costly repairs that could have been prevented.

The first thing we did was up the blower speed from the factory setting of medium speed to high speed on a previous visit, in order to help their constant torque ECM blower motor move more air through their system. The blower speed adjustment should have been done when the system was installed in 2020, but the installing contractor made no such adjustments to the system. They were paying for 3.5 tons of cooling and heating capacity, but they had only been getting a couple of tons of capacity with the system setup the way it was at install. Increasing the airflow of the blower motor did help to improve the temperature split between return and supply. It also helped to increase the system's superheat value in the cooling mode, which helps to prevent flood back of liquid refrigerant to the heat pump's compressor. The additional airflow delivery also helped to increase the system's capacity so they weren't throwing as much money away in utility bills for cooling and heating their home.

Even with the airflow adjustment on the blower motor the ductwork was still inadequate to properly operate the heat pump within its design parameters because the return ductwork was too small. We made a recommendation and created a plan of action to enlarge the return grille on the first floor along with a matching return grille box, and to add a return duct in the attic. We provided a quote for the work for the best plan of action. After some back and forth with the customer about budgeting options we came up with an alternate plan of action that better met the customer's current budget for their HVAC system.

Instead of enlarging the return grille and return grille box, the customer opted to add an additional return duct to the existing return grille and box that serviced the first floor of the home. This option didn't require us cutting a larger hole into their ceiling, was far less labor intensive, and wouldn't require nearly as much materials in order to complete the job. We provided the customer with a quote for that job and it was approved.

We were able to add a 10" flexible return duct to the existing return grille box in the attic and offset it to the side so that the customer could use the middle area for storage if needed in the future. We ran it across the attic and into the back of the return plenum at the air handler utilizing a hard pipe 90 elbow so that we could keep our 10" return duct at it's proper size. When installing any ductwork we never take shortcuts on the installation. We use top quality duct sealants on every joint in the run, we also properly secure our duct attachments with screws and Panduit straps to act as redundant backups to the duct sealants, and we always support our ductwork with nice wide straps to help prevent kinks or sagging in the future.

The customer now has the correct amount of return ductwork in order to properly operate their heat pump within it's airflow design parameters. They will now be getting the cooling and heating capacities that they have been paying for, but weren't getting, since the system was installed. Their heat pump will now be able to breathe and not starve for air. If you feel like your system wasn't set up properly and you want the job done right, please feel free to reach out to Magnolia Services in Johnson City, TN. Stay safe and best wishes.

Location: Jonesborough, TN