so be subject to the requirements of Section 15010.
B.
All heating, ventilating and air conditioning equipment which contains compressors shall be provided with extended
warranties (minimum four (4) years) for the compressors.
1.2
Description:
A.
The work to be performed shall include all labor, materials, and equipment necessary to furnish and completely
install all mechanical equipment as shown on the drawings, hereinafter specified or reasonably implied, leaving the
same in satisfactory operating condition. It is the intent that systems be installed complete, with all items necessary,
to accomplish this purpose.
2
PART 2 - PRODUCTS
2.1
Fan Forced Wall Heater (Model FRC 1.5 kW to 4.8 kW):
A.
The heating equipment shall include an electric, automatic fan forced electric air heater suitable for large area
heating as manufactured by Berko Electric, Marley, QMark or approved equal.
B.
The heater shall be designed for wall recess or surface mounting.
C.
Heaters shall be UL listed.
D.
The heater assembly which fits into the back box shall consist of a fan panel upon which is mounted all of the
operational parts of the heater.
E.
The heating element shall be of the non-glowing design consisting of a special resistance wire enclosed in a steel
sheath to which steel plate fins are copper brazed. It shall be warranted for 5 years.
F.
Fan shall be five-bladed aluminum. Fan motor shall be totally enclosed.
G.
Fan control shall be of bi-metallic, snap action type and shall activate fan after heating element reaches operating
temperature. The fan shall continue to operate after the thermostat is satisfied and until the heating element is cool.
H.
The tamperproof thermostat shall be of the bi-metallic snap action type with enclosed contacts. It shall be
completely concealed behind the front cover to become tamper proof.
I.
A thermal cutout shall be built into the system to automatically shut off the heater in the event of overheating and
reactivate the heater when temperatures return to normal.
J.
A double pole, single throw disconnect switch shall be mounted on the back box for positive disconnect of power
supply. It will be completely concealed behind the front grille panel.
K.
The back box shall be designed for duty as a recessed rough-in box in either masonry or frame installations, and is CITY OF GREENBELT

JANUARY 9, 2004
DEPARTMENT OF PUBLIC WORKS
HEATING, VENTILATING AND AIR CONDITIONING (HVAC)
15500-2
also used with the surface mounting frame in surface mounted installations. The back box shall be 20 gauge
galvanized steel and shall contain knockouts through which power leads are brought.
L.
The front panel shall be of the bar grille type and shall be constructed of 16 gauge cold-rolled steel, welded into a
uniform grille to direct the warmed air toward the floor. The front grille shall be surrounded by a decorative satin-
finish aluminum "picture" frame.
M. The heater shall be made up of a back box, a heater assembly and a front panel.
2.2
Electric Unit Heater:
A.
Furnish and install a horizontal unit heater as manufactured by Berko, QMark or Marley with heating and air
delivery capacities as shown on the heating schedule.
B.
The cabinet shall be made of 18 gauge die formed furniture grade steel. Individual adjustable louvers with 30
degrees downward stops shall be furnished to provide desired control of discharge air. All metal surfaces of the
enclosure shall be phosphate coated to resist corrosion and finished in a decorative baked enamel. Mounting
brackets designed for either ceiling or wall swivel mounting shall be furnished as shown on the heating schedule.
C.
Heaters shall be of the draw-through air flow design to eliminate the element hot spots and extend design life.
D.
Fans shall be aluminum, directly connected to fan motor, and designed specifically for unit heater application.
E.
All heaters shall be UL listed and meet the requirements of the National Electrical Code.
F.
For safety, the electric heating bank shall consist of metal sheath heating elements. The elements shall consist of
80/20 Nichrome wire and have a copper clad steel sheath for strength and corrosion resistance, and aluminum fins
for faster heat transfer. Automatic reset thermal overheat protection shall be of the linear capillary type wired for
instantaneous de-energizing in case of the thermal overload. Heating bank to have protective air inlet louvers.
G.
All heaters drawing in excess of 48 amperes shall be provided with factory installed subdivided and fused circuits
of 48 amps or less.
H.
Motors shall be totally enclosed, designed for continuous heavy duty all-angle operation and equipped with built-in
thermal overload protection.
I.
All controls and controllers shall be 120 volt/1 phase unless otherwise noted.
2.3
Electric Architectural Style Baseboard Radiation:
A.
Design draft barriers shall be 5" high and 3" wide on Model SB and 7" high and 5" wide on Model LB.
B.
The front cover shall be one piece 12 gauge aluminum construction suitable for architectural, commercial and
industrial use, with 1/4" pencil proof top discharge.
C.
The one piece cover shall be extruded aluminum for maximum strength and shall be available in lengths to 15'. The
front cover shall snap fit to the 12 gauge back cover with no screw heads or assembly fasteners. The 12 gauge back
cover shall be suitable for mullion to mullion mounting.
D.
Standard painted finish shall be provided.
E.
Heat sections from 2' through 10' shall be available. All heaters shall contain a 3/4" EMT built-in raceway with
factory wiring 1/2" and 3/4" knockouts shall be provided on the side and rear of the heater junction box to allow end
to end wiring. All blank sections shall be fully enclosed to allow branch circuit wiring. All heaters shall contain CITY OF GREENBELT

JANUARY 9, 2004
DEPARTMENT OF PUBLIC WORKS
HEATING, VENTILATING AND AIR CONDITIONING (HVAC)
15500-3
a full length linear thermal overheat protector with automatic reset. Wattages shall be available from 100 to 250
WPF on SB model and 100 to 500 WPF on model LB.
F.
Heating elements shall consist of a steel sheath and mechanically bonded aluminum fins to assure efficient heat
transfer. Element fin temperature shall not exceed 350°F to ensure long element life. Element shall be center
anchored and free floating at each end on nylon bushings.
G.
Optional controls shall include:
1.
Thermostats (single or double pole) and disconnect switches. Controls shall be tamper-proof and adjustable
with a blade screwdriver through the discharge grille.
2.
Trim panels, corners and end plates.
3.
Pedestal legs for areas with full height glass and finished back.
4.
Anodized finish as selected by the architect.
H.
All heaters are labeled by Underwriters Laboratories, Inc.
I.
Heaters shall be Rittling, American Stabilis or approved equal.
2.4
Electric Cabinet Heater:
A.
The electric cabinet unit heaters shall be as manufactured by Berko Electric, Marley or QMark.
B.
Heaters shall be UL approved, designed for mounting in any position, including on-end, fully recessed, semi-
recessed or surface mounted.
C.
Silent relays, night setback relays, damper operator and controls, remote and built-in thermostats shall operate on
24 volt circuits.
D.
The cabinet shall be of heavy duty 16 gauge cold-rolled steel. The heater shall have a hinged front door for easy
access to the control panel. The heater front panel shall be easily removable for access to elements, motor-blower
assembly, filters and all internal components. The cabinet shall be finished in desert tan baked enamel.
E.
The heating element shall be warranted for five (5) years and shall be of nonglowing design consisting of a special
resistance wire enclosed in a steel sheath to which steel plate fins are brazed. The heating elements shall be located
directly in front of the blower discharge air for uniform heating.
F.
Thermal safety cutouts shall be built into the system to automatically shut off heater in event of overheating due to
any cause. The safety cutouts shall directly interrupt power to the elements and not depend on relays to interrupt
the power.
G.
The motors and blowers shall be direct drive and resiliently mounted on a rigid heavy gauge frame for quiet
operation and long life. The motor shall be 1/8 H.P. three-speed, permanent split capacitor type with built-in
automatic reset overload protection. The motor shall be vented and mounted in the air stream to provide maximum
cooling of the motor. The blowers shall be forward curved double inlet centrifugal type which discharge directly
on the full length of the elements to provide uniform discharge air temperatures.
H.
The filter shall be located ahead of the motor and blower assembly to assure clean air circulation. The filter shall
filter both the returning room air or the outside air if a damper is provided. It shall be easily removed for changing
or cleaning by removing the front panel and pulling on the filter. A disposable filter is standard and a washable filter
is optional. CITY OF GREENBELT

JANUARY 9, 2004
DEPARTMENT OF PUBLIC WORKS
HEATING, VENTILATING AND AIR CONDITIONING (HVAC)
15500-4
I.
Fan control shall be bi-metallic snap action type and shall activate fan after heating elements reach operating
temperature, and continue to operate fan after the thermostat is satisfied and unit heating elements are cool.
J.
Integral low voltage thermostat control is standard and consists of factory built-in, snap action thermostat with
remote bulb sensor. The thermostat has an adjustment range of from 40°F to 120°F. Optional one and two-stage
wall mounted, low voltage thermostats (in lieu of bu