Common HVAC Accessories Reference
Why this matters
Whole-house HVAC accessories (humidifier, UV, electronic filter, ERV/HRV) drive added revenue + customer comfort. The HVAC tech who knows when each is needed + how to install creates significant upsell opportunities. This is the field card.
Humidifier
Bypass-type humidifier: most common; uses HVAC blower to pass air through water-soaked evaporator pad; humidified air enters supply ductwork.
Fan-powered humidifier: integrated fan; doesn't rely on HVAC blower; runs during heating cycle.
Steam humidifier: boils water + injects steam into supply duct; most expensive + most effective.
Sizing: gallons per day capacity for home sq ft + climate. Typical: 13 - 25 GPD.
Install location: supply OR return plenum.
Water supply: 1/4" line from cold water; saddle valve OR direct tap.
Drain: condensate / overflow to floor drain.
Common brands: Aprilaire (700 + 800 series), Honeywell HE365, Skuttle, Carrier.
UV light / UV-C
Coil-mount UV: kills mold + bacteria on evaporator coil; placed near coil.
Air-stream UV: kills airborne pathogens; placed in supply duct.
Common brands: Aprilaire AirPurifier, RGF, Sanuvox.
Replacement bulb: every 1 - 2 years.
Power: typically 120V dedicated outlet.
Effectiveness: well-documented for coil; debated for air-stream.
Customer education: customer often confused; explain mode of action.
Electronic air cleaner
Electrostatic precipitator: charges + collects particles; metallic plates.
HEPA-rated whole-house: media-filter style; high MERV.
Carbon filter: removes VOCs, odors; secondary to particulate filter.
Common brands: Aprilaire 5000 (electronic), Trane CleanEffects, Carrier Infinity Air Purifier.
Power: usually 120V dedicated outlet.
Maintenance: clean plates 1 - 4x annually; replace pre-filter monthly.
Electrostatic filter (washable)
Permanent filter: metallic OR synthetic media; collects via static charge.
Wash + reuse: every 1 - 3 months.
MERV equivalent: 5 - 9.
Customer often forgets to wash: degrades filtration.
Whole-house dehumidifier
Standalone humidity control: drier than HVAC alone can deliver in shoulder seasons.
Ducted OR ductless: ducted preferred for whole-house.
Sizing: pints per day capacity for home sq ft + humidity load.
Common brands: Aprilaire 1850, Honeywell DR65, Santa Fe.
Install location: typically in mechanical room; ducted to supply.
Drain: condensate to drain OR pump.
ERV / HRV (energy / heat recovery ventilator)
ERV: transfers heat + moisture between exhaust + supply streams. Humid climates.
HRV: transfers only heat. Cold + dry climates.
Mechanical ventilation requirement (ASHRAE 62.2): modern homes are tighter; require mechanical ventilation.
Common brands: Aprilaire 8126, Fantech, Broan, Panasonic.
Sizing: per ASHRAE 62.2 (7.5 CFM per occupant + 0.03 × floor area).
Install: separate ducting OR connection to existing HVAC ductwork.
Zoned HVAC (dampers + controller)
Zone dampers: motorized in ductwork; open / close per zone call.
Zone controller: coordinates dampers + equipment based on multiple thermostats.
Bypass damper: pressure relief when only one zone calling.
Common systems: Honeywell TrueZone, ZonexZ, Carrier Performance, Trane ComfortLink.
Install: requires HVAC tech familiar with zoning; not trivial.
Customer value: room-by-room temperature control; energy savings.
Smart thermostat (covered in detail in thermostat reference)
Wi-Fi + learning: Nest, Ecobee, Honeywell T10.
Multi-stage support: works with heat pump + 2-stage + dual fuel.
Customer benefit: scheduling + remote access + reports.
Carbon monoxide detector (integrated OR standalone)
Plug-in / hardwired: required by code (most jurisdictions) outside sleeping area + near fuel-burning appliances + attached garage.
Combo smoke + CO: dual-detection.
Installation by HVAC tech: common during furnace install OR upgrade.
Condensate pump
Mini-split + high-efficiency furnace: needed where gravity drain isn't possible.
Common brands: Little Giant, Aspen, RectorSeal.
Float switch shutoff: safety; shuts off HVAC if pump fails (prevents flood).
Discharge tubing: 1/4" - 3/8" to drain.
Float switch (condensate overflow)
Pan float: sits in condensate pan; rises with water level; shuts off blower / cools / heating.
Safety device: prevents overflow + ceiling water damage.
Common brands: Diversitech, Goodman, RectorSeal.
Installation: tied into low-voltage thermostat circuit (typically interrupting Y / call).
Surge protector for HVAC
Mounted at disconnect: protects compressor + control board from surge.
Common brands: Eaton, Square D HVAC-specific SPDs.
Install with: every new outdoor unit OR retrofit on existing.
Thermostat with humidity control
Detects + controls humidity: in addition to temperature.
Wireless OR wired: humidistat function.
Common brands: Honeywell, Ecobee, Nest (recent models).
Use: with humidifier OR dehumidifier integration.
Mini-split accessories
Wireless thermostat: replaces handheld remote.
Line set cover (linehide): aesthetic + protective for refrigerant lines.
Tower / wall mount kit: for outdoor unit positioning.
Condensate pump: for indoor unit drain when gravity not available.
Common HVAC accessory mistakes
Wrong humidifier sizing (under = ineffective; over = excess water consumption). Skipping float switch (condensate flood damage). Installing UV without explaining maintenance to customer. Adding electronic filter without educating customer on cleaning. Skipping mechanical ventilation in tight homes (IAQ issue).
Selling accessories
Discovery: customer comfort issues; dust complaints; allergies; static cling (low humidity); humid feeling.
Demonstrate: humidity meter showing 25% indoor (too dry); air quality monitor showing PM2.5 elevated.
Educate: why each accessory helps the specific problem.
Bundle with: new equipment install; recurring service plan.
Customer ROI: comfort, health, equipment protection, energy savings.
Common service issues with accessories
Humidifier: not running (water supply off, drain plugged, control board fail, evaporator pad mineral-clogged).
UV light: bulb expired (replace 1 - 2 yr); ballast failed.
Electronic filter: plates dirty (clean); pre-filter clogged.
Dehumidifier: filter clogged; condensate drain clogged.
ERV/HRV: core dirty; filter clogged; air balance wrong.
Float switch: pan dirty; float stuck.
Truck stock
References
- ASHRAE Fundamentals + Applications
- ASHRAE 62.2 (Indoor Air Quality)
- ENERGY STAR + ENERGY STAR Most Efficient
- Manufacturer technical data (Aprilaire, Honeywell, Skuttle, Carrier)
- Manuall internal: Ventilation Fan Ratings, Thermostat Types