Specifications

Evaporative or Steam Product Selection
Evaporative and steam humidifiers are very different in their technologies. Evaporative humidifiers do not heat the water
but use hot air flow through a water panel and the HVAC system’s heat draw to turn the water to vapor. Steam humidifiers
heat water to the boiling point, producing steam. Both technologies use the system blower to distribute humidity through
the ductwork. Steam units can be mounted with a blower pack, if a ducting system is not available.
Aprilaire offers a full line of evaporative and steam products. Both technologies are effective at delivering the right
levels of humidity throughout the home; however, it’s important that the right product is selected to ensure consumer
satisfaction.
It is important to understand these considerations when choosing the product for your consumers.
Evaporative humidification is the best choice for applications where the unit can be mounted on the duct work.
Evaporative products are easier to install, extremely reliable, last the life of the equipment, and offer an attractive
consumer price point. Steam products are ideal to fill application gaps where evaporative products can not be installed
or do not offer enough capacity. These gaps include lack of duct space on the plenum, attic or crawl space locations,
in floor heat, electric strip heat, boilers, hydronic heat and where systems experience short run times.
Geographic location of the home can also be an important selection factor in determining which Aprilaire product
to choose.
In the upper Midwest and Northeast with long, harsh winters that have extended furnace run times
and limited demand for humidification outside of a heat call, evaporative products are the primary choice.
In the south-central US along the Mason Dixon line where winters are milder and there is a high penetration
of heat pumps,andsomehumidification
is needed beyond a call for heat,
either evaporative or steam will work.
In the southwest with mild
winters and very little call for heat,
but the air is very dry, steam is the
primary choice.
CHOOSING THE RIGHT PRODUCT FOR YOUR HOUSE
Application
Recommendation
Evaporative Steam
Home Size
Up to 4,200 ft
2
tight home
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Up to 6,200 ft
2
tight home

Other
Variables
Space to mount on duct
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No freezing concerns
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Lowest cost to install

Easiest to maintain
 
Lowest cost to operate

Low heating system run-time
 
Heat pump installation
 
Possibility of freezing

Cannot mount on duct
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