We recommend contacting your local certified HVAC contractor, as they will be able to make recommendations for your home based on its age, size & construction. Overall, you can begin to understand which model might be best for your home using the following:
First, determine how much humidification your home needs, known as Gallons Per Day (GPD):
Use the 3-step formula below
Step One
Calculate the Total Cubic Feet of Home
Total Home Square Footage
X Average Ceiling Height
Step Two
Calculate the Load (lbs/hr)
Total Cubic Feet X Desired Condition Factor (Table Below)
X 1.05 for Each Fireplace
Structures Are Not Equal: Windows, Walls, Celling, Roof
Step Three
Calculate Gallons Per Day (GPD)
Gallons Per Day = Load (lbs/hr) X 2.88
Then, Select Your Unit
Once you have calculated your gallons per day you can then find models that are designed to process that amount of water / accommodate your size of home.
Keep in mind these numbers can vary based on numerous factors, including home construction, the presence and amount of woodwork, if you have a humidor or wine cellar, the presence of fireplaces, the number of floors and more. Work closely with a licensed contractor to determine the best selection for your home.
Steam Model 5500=15 GPD (115V) or 29.5 GPD (230V) up to 5,500 Sq. Ft.
The following flow through models Gallons Per Day ratings are based on 120° plenum temperature.
Evaporative Models 3200A & 3200M = 12 GPD / Up to 3,200 Sq. Ft.
Evaporative Models 4200A & 4200M = 17 GPD / Up to 4,200 Sq. Ft.
Evaporative Models 1000A & 1000M = 18 GPD / Up to 3,000 Sq. Ft.
1042LH = 17 GPD / Up to 2,800 Sq. Ft.
1099LHS = 19 GPD / / Up to 3,000 Sq. Ft.
1137 = 19 GPD / Up to 3,000 Sq. Ft.
You might also install more than one humidifier if your home has more than one HVAC system. Many people install a humidifier with each system to reduce the work load on each and more evenly distribute humidification throughout the home.