My home is on concrete slab, and the heat ducts are laid in the concrete. Most of the hot air is lost due to cold soil.
Our home is 7 years old, 2650 sf and has two furnaces. One seems to work okay, but the other does not warm the rooms quickly enough. For example, I turned the second furnace on when thermostat was at 57, and after 1 hour, it warmed up to only 60. This happened while the first furnace was off. I have moved the thermostat for the bad furnace as far away from the first thermostat as possible so they don't affect each other. My previous home in Chicago was over 3000 sf with only one furnace, and it only took about 1/2 hour to raise the inside temp by 10 degrees. My home had a basement, and the furnace was there with all ducts running through the house. Is there any way to get rid of the ducts in concrete and somehow run them through the attic? I am open to any other solutions, short of selling my present home.
I used to live in a Levitt home in Bowie, MD, and had the same issue.
I sleeved the ductwork and filled it in with concrete, running new ducts through the attic. It really helped.
For more information:
Read "My heating ducts are installed in the concrete slab of my house. I get water and dampness in them at times. Is there a way to stop it?" a Q&A answered by Andy Ault.
Also, read "How do you seal leaky ductwork?" a Q&A answered by David Edwards.