Installing the Heat Pump
Published Saturday 10/29/2021

Installing the Air Source Heat Pump

As we were getting ready to move in to our newly built house (in late 2019), our backyard landscaping was not ready for the outdoor heat pump unit to be set in place yet. So I just installed the air handler and that winter, we ran it using the backup 10kW heating element only. Not ideal but at least we were cozy all winter.


By June 2020, we finished our back patio. I set the heat pump in place and plumbed up the refrigerant lines. 

The heat pump unit on the patio in the back yard.

I fired on the heat pump for the first time and it came to life, sending cold air through our home’s ducts for the first time. Unfortunately the air wasn’t that cold and after an hour of running, the air temperature inside was no cooler than when I started. Hmmm. 

Based on the length of the refrigerant lines and the amount of R-410A the heat pump came with from the factory (enough for 15’ of liquid line), I was only about 12 ounces short of an ideal charge. 

I called an HVAC company and their technician came out to add some more refrigerant. But something was weird with the pressures, airflow across the coil and temperature of the refrigerant. It appeared that the system was extremely low on R410A. 

The technician kept adding and adding refrigerant until 7 pounds later his bottle ran out. 

Confused he opened up the air handler to look at the evaporator coil inside. 

“Ah HA!! There’s your problem” he exclaimed. 

He pointed to the obvious error in my duct work. The return air was flowing sort of across the coil and not through the coil fins. 

“Oh man, I am such an idiot”. I laughed, slapping my forehead. 

Last winter when I installed the air handler, I was only thinking about the resistive heating element and just getting the furnace part running. I completely forgot about the evaporator coil and that it too needs proper air flow THROUGH its fins, and not just near its fins. 

I told the HVAC technician that I will make the changes and call him back later to remove the excess refrigerant. He said that while there is probably way too much refrigerant running through the system, it won’t hurt it and that it will just cause it to run slightly less efficiently. 

Since we needed AC working right away, I blocked off the airflow with a scrap of vinyl siding, causing the air to pass through half of the V-shaped condenser coil surfaces. This immediately helped and the system worked surprisingly well at keeping the house cool and comfortable all summer. 

When mild autumn temperatures arrived, air conditioning was no longer needed. This gave me time to perform the needed corrections to the HVAC system. I spent a weekend repositioning duct work, lifting up the air handler, moving electrical and moving the refrigerant lines so the air handler would receive return air correctly. 

The “correct” way would have been to

  1. Evacuate the refrigerant lines
  2. Disconnect the refrigerant lines
  3. Move refrigerant lines and cut to fit the slightly shorter run
  4. Reconnect/re-solder refrigerant lines
  5. Re-charge refrigerant lines


The AC guy was out of town the weekend I decided to do this and I couldn’t find one would come out on short notice. So as an alternative to the above steps, I took a few wrongs to make a right. Don’t hate me.

Air Handler lifted up so return air can flow bottom up through the coil.

Snaked Refrigerant Coils

I spent a weekend repositioning duct work, lifting up the air handler, moving electrical and moving the refrigerant lines so the air handler would receive return air correctly.


After pulling the inside condenser coil out of the air handler cabinet, I raised it up while gently bending the refrigerant lines, forming them into a side winding snake, all while the lines were charged and while trying not to kink the lines. It ain’t pretty but it is functional. This would not have been possible without the ratcheting pipe bending hand tool purchased on Amazon for this purpose. Good enough for starting the winter season.



By winter time, the heat pump was running just fine and keeping our house toasty warm. However whenever it has to run for more than 20 minutes at a time, (like after the 3-8pm peak period is over) and it has to raise the house temperature 3 - 4°F, heat pump unit would fault out with a high pressure fault.


Sometimes it would recover from the fault and try again, eventually getting the house up to temperature. Other times the heat pump would think that it is icing up and would go into a defrost mode.

On February 5th 2021, I finally got the HVAC technician back here to help me remove the excess R410A. Immediately the heat pump was much happier and running more efficiently. It has been running without any hiccups ever since.


He sent me a bill for his services, (including 7 pounds of refrigerant that I didn’t need in the first place), and I gladly paid him. I consider it my tuition for a semester of the HVAC school of hard knocks. 


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