Siemens releases two new products for use on surfaces where condensation must be avoided. Both the QXA2601 and QXA2602 are designed to prevent condensation from forming in chilled beam and chilled ceiling applications. Both devices operate identically via a SPDT relay that changes state when humidity level near the surface of the chilled water piping approaches 92%. The unit will automatically reset when the humidity level drops to approximately 87%.
The key difference is that the QXA2601 is a completely self-contained unit that attaches directly to the chilled water piping, while the QXA2602 features a remote sensing element that is easier to locate in small spaces. The QXA2602 includes 5’ of cable for connecting the remote element to the relay housing.
Product Description: The QXA2601 and QXA2602 Condensation Monitors are used to avoid damage due to condensation on chilled ceilings and in HVAC installations. They are equipped with an SPDT dry contact capable of switching 1 amp @ 24 Vac or 0.5 amp @ 24 Vdc. A two-color LED provides visual status indication. The QXA2601 includes hardware for installation on pipes with outside diameters from 0.39 to 3.94 inches (10 to 100 mm). The QXA2602 includes hardware for surface mounting on walls or ceilings.
Product Use: For monitoring condensation in buildings that utilize chilled beam or chilled ceilings or in HVAC installations. In general, the condensation monitor is for use on surfaces where condensation must be avoided and used in following applications:
• to prevent condensation on chilled ceilings.
• to prevent condensation at critical spots of HVAC installations or buildings (in air ducts, near fans, and so on).
• as a condensation switch.
Equipment Combinations: The QXA2601 and QXA2602 can be used in any 24V AC/DC control circuit and can be wired NO or NC to provide indication of pending condensation.
Mode of Operation: With its sensing element, the condensation monitor acquires the relative humidity close to the dew point (= 100% rh). The resistance of the sensing element rises sharply in the range of 90 to 100% rh. Before the dew point is reached, the electronics energize the relay. When, as in the case of chilled ceiling applications, the relay contact switches over and may be used to trigger a condensation avoidance sequence such as:
1. Cooling will be shut down via the valve or by a controller until the condensation signal is no longer present.
2. The water flow temperature will immediately be raised by an adjustable value (typically ≈ 2˚F) and slowly reduced again after the signal has disappeared. This application requires a specific function in the controller.