The duct work was all done, and the drywall was all done, and the electrician finished wiring the house. Next it was time to finish out the heating and air conditioning system. The HVAC guy came and installed the thermostats and finished up the loose ends. Some of the ducts in the attic already started coming apart, and he had to redo them as they were installed incorrectly to begin with. He installed the returns and the vents and turned on our new HVAC systems. The city inspection was done and the systems passed inspection, and everything was finished.
We decided to give our new HVAC systems a try. The nights were still chilly, so we decided to turn on the heat to see how it works. The HVAC units are heat pumps, so we expected the air coming from the vents not to be super hot. We knew heat pumps blow out only lukewarm air. But when we turned on the heat, the air seemed a whole lot cooler than just lukewarm. The heat did heat the house eventually, but stayed on almost 100% of the time to heat it just a few degrees. This really worried us because the house has no insulation and only single pane windows, so we thought it would be almost impossible to heat the house on a really cold day or cool the house on a really hot day.
We decided to investigate this, and we found that the heat was acting very strange. The heat would go off and then cold air would continue to blow for several minutes longer actually cooling the house. This didn't make any sense.
After reading information online and reading the manuals for the HVAC systems, we realized that they were installed incorrectly. The outdoor units were set to run the air conditioning and the indoor units were set to turn on the heating elements when the thermostat was set to heat. Essentially, outdoor and indoor units were fighting each other, as one was cooling and the other was heating. This put unnecessary stress on the systems and made them run almost 24 hours a day. We called our HVAC installer, and he fixed the problem. Unfortunately, the compressor on one of the outdoor units failed. We cannot say if the failure was due to this misconfiguration for sure, but it does seem likely. The HVAC installer also replaced the outdoor unit that failed.
We were nervous that the systems were damaged due to this misconfiguration, so we negotiated a 2 year no charge warranty with our HVAC installer.
Since this was fixed, both the heat and air condition work well and easily heat and cool the house. Even with no insulation and single pane windows, we are able to have the modern comforts of central heat and air conditioning.