APRILAIRE

Aprilaire is a manufacturer of indoor air quality equipment, with a product history centered on residential and light commercial humidification. The company's humidifier line includes bypass and fan-powered in-duct units, portable console models, and the replacement pads, valves, and controls that keep those systems operating. Aprilaire humidifiers are typically installed on forced-air heating and cooling systems, where they introduce moisture into the supply air to maintain target relative humidity. The product range spans evaporative pad humidifiers, steam humidifiers, and the associated water-control components. Replacement pads are model-specific and constructed from materials such as Kraft paper, designed to present a wetted surface for evaporation while resisting mineral buildup between service intervals. In-duct units are available in bypass and fan-powered configurations, with daily output ratings that vary by model; for example, the 500M bypass humidifier is rated at up to 12 gallons per day and uses a knob control with a minimum setting around 30% relative humidity. Controls include manual humidistats and automatic units that reference outdoor temperature. Water flow is managed by solenoid valves and metering components, which regulate fill and drain cycles. Aprilaire also produces air filters, ventilation equipment, and dehumidifiers, but humidification remains the core category for replacement-part demand. 3G Electric supplies Aprilaire humidifier pads, in-duct humidifiers, solenoid valves, metering components, and related replacement parts to maintenance and procurement teams worldwide. The catalog includes pads for the 400, 500, 600, 700, and 760 series, along with valves and seals used in humidifier water circuits. Because pad part numbers map to specific model families, buyers should confirm the humidifier model and existing pad part number before ordering. 3G Electric supports the line with cross-reference data, model compatibility information, and quotation support for single-unit and volume replacement orders. The audience for these parts is primarily plant engineers, maintenance managers, and procurement specialists responsible for HVACR equipment in commercial, institutional, and light industrial facilities, as well as contractors servicing residential forced-air systems. Aprilaire parts are used wherever evaporative humidification equipment is installed and requires scheduled pad replacement, valve service, or control repair. The replacement interval for pads depends on water hardness and runtime; in hard-water areas, mineral accumulation reduces evaporation efficiency and can restrict airflow, so pads are typically replaced at least once per heating season. Solenoid valves and metering components are replaced when fill control fails or water flow becomes inconsistent. 3G Electric stocks these items as individual components rather than kits, allowing maintenance teams to order only the parts required for a specific service task. Compatibility notes in the catalog list the Aprilaire model numbers and alternate part numbers associated with each SKU, which helps reduce mis-orders when multiple humidifier generations share a similar footprint. For procurement, the practical considerations are pad dimensions, model compatibility, and material, since these determine fit and service life. For valves and metering components, the relevant specifications are electrical rating, connection size, and flow characteristics, which should be matched to the original part. 3G Electric provides quotation and order support for Aprilaire humidifier components across these categories.

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About APRILAIRE

Common Applications

Residential forced-air heating — Aprilaire 500M bypass in-duct humidifier rated at 12 gal/day for supply-duct moisture addition
Light commercial HVAC maintenance — Aprilaire 4792 replacement pad for 500 series humidifiers in scheduled seasonal service
Institutional building humidification — Aprilaire 4750 pad for 700 and 760 series units requiring periodic pad replacement
HVACR water control — Aprilaire 4040 solenoid valve for on/off water flow in humidifiers and air-treatment equipment
Commercial humidification systems — Aprilaire 4231 metering component to regulate water flow and moisture output
Duct-mount humidifier service — Aprilaire 45 Kraft paper pad for 400, 400A, and 400M models in forced-air systems

Frequently asked questions

Common questions about APRILAIRE from 3G Electric.

Which Aprilaire humidifier models use the 45 replacement pad?

The Aprilaire 45 pad, supplied under SKU 31TP37, is a Kraft paper replacement pad for duct-mount humidifiers. It is compatible with Aprilaire models 400, 400A, and 400M, and cross-references part numbers 31TP24 and 31TP25. The pad is installed in the humidifier water tray, where it provides a wetted surface for moisture transfer into the supply air of a forced-air HVAC system. Because pad fit is model-specific, confirm the humidifier model number on the unit nameplate before ordering. Pads should be replaced when mineral scale becomes visible or when the pad no longer wets evenly across its surface.

What is the daily humidification output of the Aprilaire 500M bypass humidifier?

The Aprilaire 500M bypass in-duct humidifier is rated for up to 12 gallons of humidification output per day. It mounts on the supply duct of a forced-air heating system and uses a bypass duct to route air through the evaporative pad. Control is via a knob humidistat with a minimum setting of approximately 30% relative humidity. The 500M is one of several models in the 500 series, which also includes the 500, 500A, 500K, 500MK, 500MZ, and 500Z. Replacement pads for this series are supplied under part numbers 4792 and 31TP26/31TP27. Output depends on plenum temperature, airflow, and water supply characteristics.

How do I identify the correct Aprilaire replacement pad for my humidifier?

Aprilaire replacement pads are matched to humidifier model families rather than being universal. The model number is typically printed on a label on the humidifier housing or on the existing pad frame. For example, the 4792 pad fits the 500 series, the 4750 pad fits the 700 and 760 series, and the 4839 pad fits the 600 series. Some pads also cross-reference alternate part numbers such as 31TP24 through 31TP31. If the model label is unreadable, measure the pad height and width and compare against catalog dimensions. 3G Electric lists compatible model numbers and alternate part numbers with each pad SKU to assist with identification.

What does the Aprilaire 4040 solenoid valve do in a humidifier system?

The Aprilaire 4040 solenoid valve controls water flow into the humidifier, opening to admit supply water during a call for humidity and closing to stop flow when the humidistat is satisfied. It is used in residential and light commercial humidification and air-treatment equipment requiring on/off fluid control. The valve is an electrical component, so replacement requires matching the coil voltage and connection type to the original. A failed valve can present as no water in the humidifier tray, continuous water flow, or water overflow. When replacing, isolate the water supply and confirm the valve body orientation matches the installation.

What is the Aprilaire 4231 metering component used for?

The Aprilaire 4231 is a precision metering component used in HVACR humidification systems to control water flow and regulate steam or moisture output. It is installed in the water circuit of humidifiers and supports consistent indoor humidity levels by limiting flow to the rate the humidifier can evaporate. It is suitable for commercial and residential humidification equipment where controlled water delivery is required. Because it is a metering device, the orifice or flow rating must match the humidifier model and water pressure. Replacement is typically indicated when water flow becomes erratic or when the humidifier cannot maintain setpoint despite a functioning valve and pad.

Which Aprilaire humidifier series are covered by the pads stocked at 3G Electric?

3G Electric stocks replacement pads covering several Aprilaire humidifier series, including the 400, 500, 600, 700, 760, and 768 model families. Specific SKUs include the 45 pad for the 400 series, the 4792 pad for the 500 series, the 4839 pad for the 600 series, and the 4750 pad for the 700 and 760 series. Pads are supplied individually. Compatibility is listed by model number and alternate part number on each product page. Because Aprilaire has produced multiple generations within each series, buyers should verify the exact model suffix, such as A, K, M, or Z, against the catalog compatibility list before ordering.