CON 4003 Construction Estimating Prof R. V. Locurcio

 Today… CH 14 - HVAC  Thursday… HW#7 – Thomas Filipow  Thursday… France & Lebanon

 HVAC Systems  Residential HVAC Systems  Commercial HVAC Systems

 HVAC systems consist of equipment, ductwork, and piping used to heat and ventilate buildings and to condition (cool and dry) the air.  Equipment can be: a furnace, an air- conditioning coil, a compressor, a plenum, a boiler, a tank, a pump, manifolds, outlets, and valves, etc…

 Two types considered  Residential

 Central heating and air-conditioning  Hot air systems  Hot water systems  Steam  Radiant heating used only to heat spaces

 The most common residential HVAC systems  Functions to cool and heat spaces  System consists of:  A furnace supplying heated air through ductwork  A main trunk line of rectangular duct  Supply lines running from the trunk line to the registers or vents  A return air duct returning the air from the rooms to the furnace  Metal duct using air between joists and studs.  See Fig 14.1 to Fig. 14.4

 Determine the HVAC components needed for the residence in figures 14-1 and  The furnace includes an air-conditioner.  A 2”X2” register is required at each base cabinet.  A 6”x 18” grille is needed at each return air.  Distance top of furnace to the roof is 20 feet.  The vent pipe is 4 inches in diameter.

 Equipment: a furnace, a coil, a compressor, and a plenum (enclosed space to facilitate air circulation)  For the supply trunk: 16 feet of 8”x 12” rectangular duct, two 8”x 12” to 8”x 8” transitions, 17 feet of 8” x 8”, and two 8” x 8” end caps are needed.  For the individual supply lines 6-inch 90- degree elbow are needed

 6-inch-diameter duct needed (17 ft + 17 ft + 19 ft + 19 ft + 2ft + 4 ft + 3 ft + 3 ft + 6 ft) = 90 feet  For base cabinets: three-6inch 90-degree elbow  Three 2” x 12” registers, six 4” x 12” boots, and six-4” x 12” registers  For the return air: Two-6” x 18” grilles

 Sheet metal: 15 feet of 18-inch-wide ( ) ft  Two ea. 8” x 12” end caps  12 feet of 8” x 12” duct, and 8 feet of 12” x 18” duct from the trunk line to the bottom of the furnace.

 For the vents: 2 feet above the roof and 4 feet of pipe are needed; Two 4-inch 90-degree single-wall elbows, 4 feet of 4-inch-diameter single wall pipe, 22 feet of 4-inch-diameter double wall pipe, one 4- inch roof flashing, and one 4-inch termination cap.  One line set to connect the condenser to the coil, one thermostat, and one roll of wiring are needed.

 Another type of residential heating  Uses hot water to warm the floor, which in turn warms the living space.  It consists of supply manifold, pump, boiler, return manifold, air ejector, expansion tank, and valves.  It cannot be used for cooling purposes  Figure 14-6 shows details about radiant heating

 Determine the piping needed for a radiant heating system for a 10’ x 10’ room.  The pipe spacing is shown in figure  Allow 40 feet of pipe to connect the pipe in the room to the boiler.

 Two types considered Commercial

 Small commercial buildings often use HVAC systems similar to that of the residential system, using more units as the building gets larger.  Larger single-story buildings often use a roof-top units (package units) that heat and cool the air and then distribute it through the building using ductwork.  As building gets taller a heat exchanger is used. The heating and cooling is accomplished by heating or cooling water at a central point.  Commercial systems may also use chillers, boilers, dampers, fans, and variable-air-volume (VAV) boxes.

 Determine the HVAC components needed for the commercial HVAC system shown in Figure  Two feet of 6-inch-diameter flexible duct is used to connect the diffuser to the ductwork.  The plenum is used for return air. The existing supply and return lines are made of copper.