Pros, Join Our TradeMaster Program!
Model DFS-221 is an airflow proving switch designed for duct heater, oven, and other HVAC or Energy Management applications where an open-mounted, nonadjustable switch is desirable. It is especially suitable for surface-mounting in areas where internal access is limited. It can be used to sense positive, negative, or differential air pressure. The DFS-221 is equipped with a convenient barbed sample line connector that accepts flexible tubing.
Hide Description
Manuals (1)
Setpoint Range:

.05" to .02" WC

Max Pressure (PSI):




Electric Connection:

1/4" Quick-Connect Male

Operating Temp Range:

-40°F to 180°F


Diaphragm Vertical


Product Review

Product Q&A

Add-on Item

This item is cost-prohibitive to ship on its own but is available to ship with orders over $200.

Why don't we show the price of this item?

We try to always offer you the lowest prices possible, but some manufacturers require that we only show these low prices once you take further action.

To see the price, simply add the item to your cart or sign in.