Living space with heater

Horizontal with Bottom Return Air Plenum / LH-Q


Horizontal with Bottom Return Air Plenum / LH-Q

Product Details

The Horizontal with Bottom Return-Air Plenum (LH-Q) is a low-static (up to .25 ESP) fan coil that comes with a coil, blower/ motor assembly with quick-connect plug and a galvanized steel, powder-coated epoxy drain pan covered with ⅛-inch thick insulation. The galvanized steel plenum is insulated with ½-inch thick, over three pound density, neoprene-coated fiberglass. The plenum conceals the fan and motor assembly that is easily accessed for service by removing the back panel. This unit is easily mounted above ceilings, in closets, and in hallways.

WARNING: This product can expose you to chemicals including epichlorohydrin which is known to the State of California to cause cancer and birth defects and/or other reproductive harm. For more information go to



All unit chassis shall be fabricated of heavy gauge galvanized steel panels able to meet 125 hour salt spray test per ASTM B-117. All exterior panels shall be insulated with 1/2″ thick, 3.35 pound per cubic foot, dual density fiberglass insulation rated for a maximum air velocity of 3600 f.p.m. Insulation shall conform to UL 181 for erosion and NFPA 90A and 90B for flame spread (25) and smoke developed (50) rating per ASTM E-84 and UL 723 and CAN./ULC, S102-M88.

All plenum units shall have a minimum 1″ duct collar on the discharge and minimum 1″ duct collar on the return.

Available Options:

  • Provide foil faced insulation in lieu of standard. Foil insulation shall meet or exceed the requirements stated above, and in addition, meet ASTM Standards C665 and C-1136 for biological growth in insulation. Insulation shall be lined with aluminum foil, fiberglass scrim reinforcement, and 30 pound kraft paper laminated together with a flame resistant adhesive. All exposed edges shall be sealed to prevent any fibers from reaching the air stream.
  • Provide elastomeric closed cell foam insulation in lieu of standard. Insulation shall conform to UL 181 for erosion and NFPA 90A for fire, smoke and melting, and comply with a 25/50 flame spread and smoke developed Index per ASTM E-84 or UL 723. Additionally, insulation shall comply with antimicrobial performance rating of zero, no observed growth, per ASTM G21. Polyethylene insulation is not acceptable.
  • For exposed units, the bottom access panels shall be attached with quick open fasteners to allow for easy removal and access for service.
  • For exposed units, provide double deflection discharge grille and either a rear return or bottom return single deflection grille. Supply and return duct connections are available. Unit mounting shall be by hanger and slotted hanging brackets provided at four locations. For easy installation, exposed units provided with 1/2″ mounting knockouts in four places.


Unit fan shall be a dynamically balanced, forwardly curved, DWDI centrifugal type constructed of heavy gauge zinc coated galvanized steel for corrosion resistance. Motors shall be high efficiency, permanently lubricated sleeve bearing, permanent split capacitor type with UL and C-UL listed automatic reset thermal overload protection and three separate horsepower taps. Single speed motors are not acceptable.

The fan assembly shall be easily removable for servicing the motor and blower at or away from the unit. The entire fan assembly shall be able to come out of the unit by removing two wing nuts and unplugging the motor.

Plenum unit fan assemblies shall be easily serviced through an access panel provided.

Available Options:

  • Devices used to energize and de-energize (switch) fan speeds must be totally silent. Mercury and/or quiet relays and/or contactors are not acceptable


All cooling and heating coils shall optimize rows and fins per inch to meet the specified capacity. Coils shall have seamless copper tubes and shall be mechanically expanded to provide an efficient, permanent bond between the tube and fin. Fins shall have high efficiency aluminum surface optimized for heat transfer, air pressure drop and carryover.

All coils shall be hydrostatically tested at 350 PSIG air pressure under water, and rated for a maximum of 300 PSIG working pressure at 200°F maximum water temperature. Direct expansion cooling coils shall include a fixed orifice distributor and nozzle.

Steam coils shall be standard steam type suitable for temperatures above 35°F and 15 PSIG maximum working pressure.

Available Options:

  • Coil casing shall be fabricated from 304 stainless steel. All coils shall be provided with a manual air vent fitting to allow for coil venting.
  • Provide automatic air vents in lieu of manual air vents. Cooling and heating coils shall be in the common coil casing, heating coils shall be furnished in the re-heat or pre-heat position on the unit with chilled water coils, and DX heating coil shall be in pre-heat position only.


Furnish an electric resistance heating assembly as an integral part of the fan coil unit, with the heating capacity, voltage and kilowatts scheduled. The heater assembly shall be designed and rated for installation on the fan coil unit without the use of duct extensions or transitions, and be located in the unit as to not expose the fan assembly to excessive leaving air temperatures that could affect motor performance.

The heater and unit assembly shall be listed for zero clearance and meet all NEC requirements, and be UL listed with the unit as an assembly in compliance with UL/ANSI Standard 1995.

All heating elements shall be open coil type Nichrome wire mounted in ceramic insulators and located in an insulated heavy gauge galvanized steel housing. All elements shall terminate in a machine staked stainless steel terminal secured with stainless steel hardware for corrosion resistance. The element support brackets shall be spaced no greater than 3-1/2” on center. All internal wiring shall be rated for 105°C minimum. All heaters shall include over temperature protection consisting of an automatic reset primary thermal limit and back up secondary thermal limit. All heaters shall be single stage. An incoming line power distribution block shall be provided and designated to accept single point power wiring capable of carrying 125% of the calculated load current.

Available Options:

  • Devices used to energize and de-energize (switch) electric heat must be totally silent. Mercury and/or quiet relays and/or contactors are not acceptable.


All plenum units shall be furnished with a minimum 1″ nominal glass fiber throwaway filter. Filters shall be tight fitting to prevent air bypass. Plenum unit filters shall be easily removable from the bottom or rear of the unit without the need for tools.

Available Options:

  • Provide unit with 2″ pleated filters rated at 25-30% efficiency and MERV 6 based on ASHRAE 52.2 – 1999 Electrical (Option) Units shall be furnished with single point power connection. Provide an electrical junction box with terminal strip for motor and other electrical terminations.
  • The factory mounted terminal wiring strip consists of a multiple position screw terminal block to facilitate wiring terminations for the electric control valves and thermostats.


Provide a factory assembled valve piping package to consist of a 2 or 3 way, on/off, motorized electric control valve and two ball isolation valves. Control valves are piped normally closed to the coil. Maximum entering water temperature on the control valve is 180°F, and maximum close-off pressure is 75 PSIG (1/2″) or 50 PSIG (3/4″). Maximum operating pressure shall be 300 PSIG.

Available Options:

  • Provide 3 wire floating point modulating control valve in lieu of standard 2 position control valve with factory assembled valve piping package.
  • Provide either a fixed or adjustable flow control device for each piping package.
  • Provide pressure temperature ports for each piping package. Piping packages are shipped installed on all units and can be shipped separately by request only.


Primary condensate drain pans shall be single wall, heavy gauge, powder-coated epoxy subjected to a 650 hour salt spray test in accordance with ASTM B117, and shall extend under the entire cooling coil. Drain pans shall be of one piece construction and be positively sloped for condensate removal. Drain pans shall have primary and secondary drain connections.

The drain pan shall be externally insulated with a closed cell foam insulation. The insulation shall carry no more than a 25/50 Flame Spread and Smoke Developed Rating per ASTM E-84 and UL 723 and fungi resistant per ASTM G21/C1338, bacteria resistant per ASTM G22 and mold growth per UL 181.

Available Options:

  • Provide a single wall primary drain pan constructed entirely of heavy gauge type 304 stainless steel for superior corrosion resistance. Stainless steel drain pans shall be externally insulated and meet or exceed the requirements stated above. Provide a secondary drain connection on the primary drain pan for condensate overflow.
  • Provide a condensate overflow switch in the primary drain pan for condensate overflow.