Residential heating and cooling systems are the largest energy user in your home and one of the most important things in your home comfort.
HVAC systems come in many different sizes, types, configurations and efficiency ratings. When we choose any HVAC system, actually we are choosing to capacity of the system to move BTUs either into a structure or out of a structure.
When it comes to sizing HVAC system “bigger is better” saying is does not work,“bigger” is definitely not better, “small” is not enough. For that reason, heating system is crucial and must have the proper size for reliable and efficient home comfort.
What is BTU and why proper size heating cooling system is so important?
Proper size heating system capacity is measured with BTU, which is stands for “‘British Thermal Unit”. BTU is the approximate heat energy required to raise 1 lb. of water 1 deg Fahrenheit, (e.g. from “59 F” to “60 F”) (A wooden kitchen match produce approximately 1 BTU ).
In air conditioning system, BTU equates to tonnage.
1 ton of cooling equivalent to 12,000 BTU/h. It is the amount of power needed to freeze 1 ton of water into ice in 24 hours.
12,000 BTU/hr is equivalent to 3,516 Watts – or 3.516 kW (kilo-Watts).
- How do we can find what size heating and air conditioning system we need?
- What happens if we do not have the right size heating and cooling system?
For proper size system we need to know how much heat the structure loses cold heating season, and how much heat the structure gains in the warm cooling season. After some series calculations regarding structure we can determine what size heating and cooling system we need. These calculation are called “heat gain and heat loss calculation”.
An undersize system will not be enough to heat your home. When cold winter days start and temperature different increase between indoor and outdoor , your furnace will run constantly but can not deal with the larger temperature deviations. It will have to work extra hard to heat your home. Your heating energy cost will increase and your comfort will never exist.
An oversized system with the cycle “on and off” very often and reduce the heating system operating life. On/off cycles can not work efficiently and use more energy and can lead to higher energy cost bills.
Warm air is lighter than cold air, so it rises while cold air falls. The air is constantly moving during to furnace on. But oversize furnaces can not provide longer operation cycles for better air mixing.
Another negative effect of short-cycle is decreased de-humidification and leads to higher relative humidity in your house. If we have higher relative humidity, we will feel more warm air but this high humidity provides an increase in the possibility of mold growth.
A properly sized heating system will provide a high level of comfort and high efficiency.
It will decrease the high level humidity and will help to increase indoor air quality.