I hope you have readings on the temperature downstairs and have a statement from the HVAC saying the unit is in good working order.Lastly, you are going to need a good attorney and it is going to cost you some money.

After several days of cleaning and not being able to put a dent in the smell I realized it would get better and worse to humidity and temperature.

We had several days of single-degree temperatures here in Connecticut this past week, and a squatter broke into the basement of an 8-unit apartment building that we manage.  

We had 30" snow last weekend, and temperatures rose today to 45 degrees and pouring rain.

I didn’t find any unicorns yet of how to keep it super warm but will see if the cover makes a material difference Insulate your pool: Adding a pool cover or blanket can help to keep heat in the water and reduce the amount of energy needed to maintain a comfortable temperature.Set the thermostat correctly: Set the thermostat to the desired temperature and avoid making frequent adjustments, as this can cause the heater to cycle on and off more frequently, which can increase energy usage.Keep the heater clean: Make sure to clean the filter and other parts of the heater regularly to ensure it is operating at its best.Use a timer: Use a timer to turn the heater off when it is not in use.

You can auto set the temperature to return to a set point at various times of the day.

It's not like electricity where the temperature and the season will cause it to rise and fall at different intervals.

Everyone has a different comfort zone for temperature, so if they want it cold, they can pay for it.

Aloha,Rather than a thermometer to give you only the current temp, I recommend you get a temperature data logger such as this:https://www.amazon.com/Elitech...You place this in a room for 24 - 48 hours and it will chart the temperature over time, clearly showing when HVAC cycles on and off.

Temperature control.