We bought a rental property along the lake upstate and knew that we would use it for a few weeks out of the year ourselves too. It would be a great way to have a vacation property that paid for itself. We made sure to have is furnished with just about everything a renter would need with the exception of their food and linens. We even purchased kayaks for the lake that they could use. We only used the property in what would be considered the “off season” because we didn’t want to limit the renters from their choices dring prime vacation times. Since the weather was always mild while we were there, we were able to have the windows and doors open. We seldom used the HVAC system. If we did turn on the heat or air conditioning it was only while we were sleeping. For this reason, we never noticed the problem with the windows. We started getting monthly bills for the utilities during the rental season and couldn’t believe how high they were. When my brother went to check it out he found that the HVAc system was running almost non stop. He checked the thermostat and it seemed fine. He then noticed a draft in the living room and found that the windows were not sealed properly. The HVAC system was running so hard because the cold air from outside was penetrating the windows. We called a local contractor to fix the problem and then had the HVAC system serviced. We figured it had been working so hard that we might as well have it tuned up and make sure it wasn’t damaged.