When we bought our ranch, we knew that we wanted to add central AC someday. It was not a high priority at the beginning, especially given that we had a leaky roof and a fire-hazard electrical panel to deal with.

Then a two-week long heat wave hit the Midwest…After a week of 90 degree days and nights, we quickly relabeled the central AC a “high priority” and started calling around. Lucky for us, we found a local company who could install both furnace and AC for us within a week!

After making a bunch of decisions, our installation was scheduled. We still needed to decide the location for pipe/duct work. Certain criteria had to be met for code and safety reasons, so we could not just hide all the ducts and pipes behind walls. But we could try to utilize existing ducts to minimize exposed pipes and avoid cutting new holes on the brick.

1. The copper refrigerant line

The first decision we needed to make was how to connect the condenser outside to the central AC unit that sits on top of the furnace. If you remember our basement layout, the furnace (marked with “F” in the picture below) sits in the corner of the utility room, and our condenser unit (marked with “C” below) will sit on the northeast corner of our house, outside of our bedroom wall.


You can see where the copper lines (containing refrigerant) between them (marked as yellow). The copper lines need to be as straight as possible, as tight turns will compromise the pipe and may cause leaks down the road. That means that they need to run perpendicular to our floor joint (from west to east). We certainly do not cut holes on the floor joint, so the copper lines has to run below the ceiling in the bedroom.


Above is the basement bedroom the lines will go through. The copper lines will come in from the ceiling from the right side (so we cut a hole on the brick instead of on the foundation), and run just below the ceiling to the left. We will keep it as close to the closet door and the existing duct as possible. From the bedroom going out, there was an existing duct in the wall that reaches the furnace, so that portion of the copper lines can be hidden.

2. The PVC pipes for air circulation

For a high efficiency furnace, two PVC pipes have to be put in to air the furnace, as shown above in blue lines. One pipe is to exhaust, and the other one is to supply fresh air. We could have run the PVCs directly above the furnace and out to the back of the house, but we would have to cut new holes on the brick. Luckily, there was an unused duct on top of the dry wall that separates the utility room and the weird bedroom:


It is connected to outside already so new PVC pipe can just thread through.


To gain access to the existing duct, we needed to remove the door frame and the dry wall around the pipe. So Slav got to work the day before the HVAC installation.


He first removed the ceiling around the doorway, then cut off the corner studs and chipped off all the dry walls around the existing pipe.






3. Getting rid of the old fresh air pipe and correct the gas lines

This was what the utility room looked like BEFORE installation…


This photo shows at least 5 code violations here according to our HVAC guy. I am glad we got this mess taking care of!

For respective, I labeled what these ducts and pipes were for:

HVAC room

As you can see, the new furnace will be a bit taller, and the new AC unit will sit right above it. The electrical supply pipe will remain and continue to give power to the furnace, and the thermostat will be rewired.


One thing will be gone with the old furnace is the old fresh air supply pipe to the furnace (blue arrow), which was hanging by a thread (literally) at 45 degrees. Another change will be to rewire the gas line. The current gas line ran across the top of the furnace, came down on its left side, and supply the furnace through a weird U curve. The U pipe not only blocked the furnace front panel and made changing filter a lot more difficult, but also increased the possibility of leakage. We will bring down the gas line down on the right side of the furnace instead, so the connections are more straight forward. The new furnace can also sit a couple inches closer to the wall.

We would love to see the old fresh air supply pipe for the furnace (the vertical pipe) go away, but we have to keep it since it doubles as the fresh air supply for the water heater. When we replace the water heater with a high efficiency one, or even better, a tankless one, it will use PVC for fresh air and the old fresh air pipe will go away completely.


4. Getting rid of the old furnace

With all the road block cleared out, our HVAC guy arrived the next morning with brand new units:




The new furnace from the bottom


The AC unit!


The first step was to cap the gas line and clear out the old furnace:



It was nasty – after an hour or so, the old furnace was out on the curb:


5. Setting up the refrigerate lines/copper pipes

While one guy (John) was inside removing the old furnace, his helper (Chase) went outside to set up the condenser unit:


Our electrician has already put in the AV outlet and a service outlet prior installation.

Chase leveled the ground, measured where exactly the supporting pad would go (a foot from the exterior wall and windows by code), then put down the pad. We made a last minute decision to add two poly layers below the pad, so water would not get into the gap between the condenser and the foundation.


Then Chase rolled out the copper lines:


These two lines would run along the bedroom and into the AC unit. You can see the form insulation around the copper pipes:


A hole was drilled on the side wall for the pipe to come into the house, just above the foundation:


It took both guys to push the copper lines through the hole and into the bedroom:



The next step was to run the pipe through over the bathroom and into the utility room. As I told you before, there was an existing duct already. The guys inserted a rigid PVC pipe through the duct, in order to piggyback the soft copper pipes into the utility room:



After some wrestling, the copper lines were finally in:


And this was what the bedroom looked like with exposed pipe. At the end of the installation, John kindly bent the pipe a bit so it runs closely next to the air duct. We plan to build a soffit down the road to hide the pipe.


Once the copper lines were in place, the guys moved to the outside to connect the copper pipes to the condenser:





6. Installing new furnace and AC unit

After the condenser unit was connected, the guys moved inside again to install the new units:


The capped gas line:


According to the code, a flexible (yet sealed) duct connector has to be put into any pipes that run vertically. This is to prevent leakage caused by potential ground shift – basically, if there is an earthquake that moves the pipes around or up and down a few inches, , the pipes should still be sealed.


The new furnace and AC unit were installed from ground up. The base of the new furnace was connected to the existing return duct:


The furnace unit and AC united were added on top. And the copper line and gas line were reconnected:


An additional PVC pipe were added to guide the condensation from both AC unit and furnace to a pump, which was connected to the floor drain.


7. Connect the exhaust and fresh air pipes

The last step was to set up the two PVC pipes for fresh air and exhaust.  Two PVCs were fed into the utility room from the outside:


And making their way into the utility room:





And the outdoor piping were cut to certain length and bent to different angles to make sure that the exhaust air is far enough from exterior windows and the fresh air intake.


8. Fill the copper lines with refrigerate

After these were all done, the air in the copper lines were vacuumed out and the refrigerate were pumped in:


We had cool air! Slav could not take the window ACs down fast enough.


And the northern side of our house went from this:


To this:


There are still lots of things we could do to improve the look here. We plan to

  1. Cover the refrigerate line with metal covers and paint it to match our trims.
  2. Replace all the old window wells.
  3. Grade around the foundation and put decorative rocks along the foundation.
  4. Create a private entrance to the basement on this side of the house someday.