Good Questions — Honest Answers

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Should a Skuttle Bypass Flow-Thru Humidifier be mounted on the warm air or the cold air plenum?

Either option will work fine. Mounting a Bypass Flow-Thru Humidifier (Model 2000, 2100, 2001 or 2101) on the warm air supply or the cold air return plenum does not alter humidifier performance. In either location, air will flow from the warm air to the cold air side due to the positive and negative pressures of the heating system. Connect the humidifier to the opposite plenum using 6 in. (15.24 cm) round duct.
NOTE: Mount the Model 2002 or 2102 Fan-Powered Flow-Thru Humidifier on the warm air plenum only.

On the 60-Series Steam Humidifiers, is the fan control wiring 24, 120 or 240 volt?

The fan control wiring for all 60-Series Humidifiers (Models 60-1, F60-1, 60-2, F60-2 and 60-BC1), is 24 volt, low voltage only.

Is there an effective but less expensive alternative to steam for High-Efficiency Furnaces?

If you install 90-plus furnaces, consider recommending Skuttle’s Model 55UD Under Duct Flow-Thru Humidifier or Model 86UD Under Duct Drum Humidifier to customers who can’t afford the luxury of a steam unit. Both under duct humidifiers are productive workhorses that are superior to plenum-mount flow-thrus on high-efficiency furnaces. Here are a few reasons why….

  • Under duct units handle more air volume because air flows directly through the ductwork rather than being diverted through a 6 in. (15.24 cm) bypass tube.
  • With normal maintenance, they cause almost no airflow resistance. In fact, the designs of the 55UD and 86UD actually expand airflow space around the humidifier pad.
  • Under duct units are faster and easier to install.
  • Model 86UD, like plenum-mount drums, uses minimal water and electricity, making it among the most economical and ecologically friendly humidifiers to operate.

In situations where there are two trunk lines extending from the furnace, is it helpful to install two under duct humidifiers (i.e., one on each line)?

As long as a single 55UD Under Duct Flow-Thru Humidifier or 86UD Under Duct Drum Humidifier can handle the cubic footage of the home, a second unit on a second trunk line is pointless. The reason has to do with the way humidity travels.
Humidity always travels through its surrounding gas mixture (in this case, the air in the home) at 25 feet (7.62 meters) per second. If you were to introduce humidity into a 50-by-50-foot (15.24-by-15.24-meter) home, the humidity would take just two seconds to disperse evenly throughout the house.

Is it necessary to hook up the outdoor sensor on the Compustat Automatic Humidifier Control?

Yes. The outdoor sensor is what makes Compustat so great for your customers. This set-it-and-forget-it system ensures the homeowner that, regardless of fluctuations in outdoor temperature, the home’s proper humidity level (35-45 percent) will be maintained. However, Compustat cannot perform this vital function if the sensor is not hooked up.

What is the difference between the Safety Control Shutoff and the Model A50 Current Sensing Relay?

Skuttle’s Safety Control Shutoff (formerly called a Safety Control Relay) is used exclusively with Skuttle 60-Series Steam Humidifiers, and is designed to prevent them from operating if the furnace blower fails. This helps protect HVAC equipment and homes from water damage and/or mold growth. The Safety Control Shutoff cannot be used as a current sensing relay.
The Model A50 Current Sensing Relay, on the other hand, is designed for interfacing humidifiers with all types of forced air furnaces and air conditioners. Humidifier installations using the A50 depend on the furnace blower to initiate humidifier operation. As a result, the Current Sensing Relay’s function is essentially opposite that of a Safety Control Relay.