Why do different customers perceive thermal changes differently? The short answer is, they have a different frame of reference.
The Long AnswerThe human body's ability to adapt to varying levels of heat and cold is part of the reason why our species has survived. It is controlled by the central nervous system (including sensors in the skin), the muscular system, and the circulatory system. The thermostat is actually a go-between for the home's heating-cooling system and the body's control system.
The body has two ways of perceiving external stimuli: through sensation and through perception. There is something called the absolute threshold - the point at which a change in the environment becomes noticeable. Is a 0.5 degree change detectable to a person? No, but a 5 degree change is.
A person's perception of temperature depends to some degree on the temperature they were in before. To the person coming inside from shoveling snow on a winter's day, the house feels nice and warm. The person who was already inside at a desk might feel cool. The person who comes in chilled might feel the need to turn up the thermostat, then drinks a cup of something warm, shivers a little bit, puts on a sweater, and gradually warms up. Once their body adjusts, they turn the thermostat back down because now the space is "too hot."
The human body also uses "homeostasis" to maintain a stable internal environment - that is, inside the body. The body's nervous system sends feedback about temperature and responds to bring the body to a stable condition. Too cold? The nerves send messages that start the muscles shivering, which helps warm a person up. Too hot? The nerves send messages that start perspiration.
Why do people complain about being too hot or too cold? There are many cases where the mechanical system is not functioning as it should, either from a control or delivery standpoint. That's where you come in.
Getting To The HeartWhen you are troubleshooting a customer's comfort problems, look for the obvious problems first. If there is a cold spot in the house, check the ductwork - is enough air coming out? Could there be a duct leak? Have they blocked their own vents?
Where has the thermostat been placed? Is it in a direct path of a heat source? Has the room configuration been changed? Could this customer be a candidate for zoning?
Is the thermostat responding properly? Is the customer comfortable using their thermostat? Are occupants in larger buildings having "thermostat wars?" Feeling in control of the system plays a big role in a customer's comfort. Perhaps it is time for a different thermostat, or a refresher on using their existing one.
Are there other aspects of comfort that need to be addressed? Is the home's humidity (or lack of humidity) contributing to comfort problems? High indoor humidity in summer could have multiple causes, and it does make people feel more uncomfortable even when the air is being cooled.
It is critical to take comfort complaints seriously. Offer solutions based on your knowledge and experience. Your customers will have the added comfort of working with an HVAC technician of integrity.
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