Best Local residential plumbers - Do's N Don't's - troubleshooting, installation - diagnosis & repair - Free contractor estimates - roto rooter services, solar water heater repair, septic cleaning services, underground leak detection. Constantly moving air through ductwork (with little to no insulation) — in an attic space which is as hot as 160+ degrees in the summer, and (at best) only minimally warmer than the outside air in winter, transfers heat from the attic to the living-space in summer and cold from the attic in winter ..More
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Lower Cooling Bills — Is Your A/C Cooling At Its Best? (Part 3 of 5)
Air-flow is restricted by dirty air ducts. If nothing about your HVAC has changed, but you are starting to notice its performance or air-flow dropping, you are likely overdue for a duct cleaning. This is especially true if you have shedding pets. Below is a before / after photo of the same ductwork, showing what had built up inside the ductwork. Note: It appears what’s on the bottom of the duct looks different than what’s on the sides and top. It is likely built up pet hair.
If you would like more detail on symptoms that indicate your HVAC System and Ductwork needs cleaned, click on this link: Signs Your HVAC System Needs Cleaned
Cleaning ductwork does FAR more than restore air-flow. If you have ductwork full of dust or pet hair, the furnace is blowing air over contaminants each time it runs. Also, ductwork often sweats in summer, due to DFW’s high humidity levels. When moisture is present, mold has all it needs to grow (dust & moisture). If mold exists in the ductwork, mold spores are blown all over the house each time the furnace blower runs.
Note: If your a/c smells musty when it turns on, it’s often a sign of mold. You probably won’t smell the odor in winter because the ductwork is very dry. When mold dries out, with no source of moisture, it dies. When this occurs, most of the odor caused by mold mostly disappears. You may also notice breathing issues in summer that don’t happen during winter.
The frequency of cleanings is determined by:
In many homes, the return-air for the entire house flows through only 1 or 2 Central Air-Return(s). In homes with return-air ducts in most rooms (never in kitchen or baths) roughly the same amount of air entering each room (from the ducts) as is existing the room through its return-air grill.
Often, a Central Air-Return will be below the furnace (if furnace is located within the living space) right against the floor. The grill covering this duct will get dirty faster, and needs to be cleaned more frequently that other return-air grills to ensure maximum air-flow.
Just like dirty ductwork, all the air in the home is passing over contaminants as it enters the HVAC System. Most ductwork cleaners remove the return-air grills as part of the cleaning service. Grills typically get dirty sooner than ductwork, especially if the return-air duct is at the floor, and even more so with shedding pets. In most cases, the grill can be cleaned with the brush on a vacuum cleaner. If the grill is sticky (due to cooking grease or smoking) it needs to be cleaned with soap and water.
This is more likely in older homes. There is a gap between the ceiling (or wall) and the edge of the metal where the duct or grill attaches. This allows cooled or heating supply-air to end up in the attic, AND return-air to be pulled from the attic. DFW attics are up to 160 degrees in the summer, and close to the outside temperature winter. Because the air coming from the supply-air ducts has pressure on it (it’s moving), notable amounts of air will pass through a gap into the attic. In winter, warm air from both the HVAC Systems + living space also escapes through the gap (warm air rises and exists gaps in the ceiling).
All openings in walls and ceilings
leak air into or out of the home.
Because warm air rises, warm out exits the home through openings in the ceiling. As warm air exists, cold air enters the home through openings in the walls (and other areas).
Air Leakage Can Nearly Be Eliminated At Outlets & Light Switches By:
In Winter: Warm air rises, and exits the home through ceiling openings. Then, cold (outside) air enters the home anywhere the home is leaking air near the floor.
In Summer: Because cold air is more dense than warm air, cold “travels to warm”. In summer, cool (air conditioned) air can exit the home anywhere the home is leaking air near the floor.
NOTE: When the fireplace is not in use — close the damper. Leaving it open creates a space (up to 24″ wide & up to 18″ deep) for warm air to rise out of the house.
NOTE: Many fireplace dampers warp (from heat) and cannot seal tightly. A solution can be the “Fireplace Balloon”. Inflate it and push tight against the top of fireplace for a tighter seal. If a fire is lighted with balloon in place it will melt a little and deflate.
NOTE: Keep windows locked when not open. It’s difficult to tell if they are fully closed unless locked. If not fully closed and locked: air, bugs and burglars can enter at will.
Check under entry doors for visible daylight. If you can see light, install a seal at the bottom of door (many types are available). Wedge-Gaskets seal the gap on the side of the bottom of door.
Even ductwork with a perfect installation can degrade over time. Some sealing products may harden & crack, starting a leak. Also, duct tape fails in DFW attic heat within months. It may appear to be in place, but is actually no longer sealing anything (see left photo).
It’s quite possible a worker may bump ductwork while in the attic, causing it to come ajar or completely apart.
Perfectly installed ductwork can come apart over time. This can be a normal occurrence, or due to the ductwork having been damaged.
They measure how much are is going into the ductwork (at return-air grill openings) versus how much air is coming out of the system (at supply-air duct openings). Purchasing a ductwork-leakage test may be a investment with tremendous benefits for you.
Leaking supply-air ductwork sends cooled / heated air into the attic, causing the HVAC System to run longer and harder. If there are leaks in the return-air ductwork in the attic, air up to 160 degrees in temperature is coming into the HVAC System.
Attic air is up to +90 degrees warmer than what an HVAC System is designed to cool. With a 15 degree cooling-spread (what a properly working a/c can do) the air ending up in the living-space is cooled to only 75 degrees (versus 55 degrees for the air coming from inside the 70 degree home). If your home has the average of 15% ductwork leakage, you can reduce cooling / heating costs by up to 15% by sealing the leaks. In addition, the HVAC System will last longer.
In DFW, when you run the blower all the time, you transfer heat (from the attic) into the living-space during summer. In winter, you transfer cold (from the attic) into the living space.
TX Building code requires ceilings to have R-38 insulation. TX Building Code allows the ductwork to be R-6 to R-8, and older Flexible ductwork has an R-Value as low as 4. Older Metal ductwork may be uninsulated.
Constantly moving air through ductwork (with little to no insulation) — in an attic space which is as hot as 160+ degrees in the summer, and (at best) only minimally warmer than the outside air in winter, transfers heat from the attic to the living-space in summer and cold from the attic in winter.
Why does ductwork have less insulation? Because air is intended to be moving through ductwork for only a short period of time (from the time it takes air to move from the furnace through the ductwork and into the rooms. If you run the blower all the time, air is constantly moving through the ductwork. So, air is always moving through ductwork with R-8 insulation (or less) inside attics that are extremely hot or quite cold.
And, since most ductwork leaks air, you are constantly losing cooled / heated air into your attic. You are also paying to operate the blower all the time. All this adds up to higher cooling and heating bills and wasted energy.
Differing opinions exist about the question of running the furnace blower all the time. This is because the answer can be different depending on where you live within the United States. In the northern U.S. most homes have a basement that stays 55-60 degrees year round. The furnace and ductwork in these homes is located in the basement.
Typical DFW attic ventilation looks like these photos.
Many newer homes look like the 2 photos on the right.