York DGPH077ABTA warranty Return Air Requirements, Air Distribution Systems, 035-16328-Rev002C0902

035-16328-Rev002C(0902).

RETURN AIR REQUIREMENTS

CLOSET INSTALLATIONS

Additional Requirements

Additional requirements for floor and ceiling return system for closet installed sealed combustion heating appliance are given in the next paragraph.

Floor or Ceiling Return Air System

Listed in the next paragraph are the conditions to be met by Manufactured Home Manufacturers to have U.L. acceptance of in-floor or ceiling return air systems of closet installed direct vent forced air heating appliances for Manufactured Homes to be sold in the United States.

1.The return-air opening into the closet, regardless of loca- tion, is to be sized not less than specified on the appli- ance's rating plate.

2.If the return-air opening is located in the floor of the closet (versus the vertical front or side wail), the opening is to be provided with means to prevent its inadvertent closure by a fiat object placad over the opening.

3.The cross-sectional area of the return duct system (when located in the floor or ceiling of the manufactured home) leading into the closet is to be not less than that of the opening specified on the appliance's rating plate.

4.The total free area of openings in the floor or ceiling reg- isters serving the return-air duct system is to be not less than 150% of the size of the opening specified on the appliance's rating plate. At least one such register is to be located where likelihood of its being covered by car- peting, boxes, and other objects is minimized.

5.Materials located in the return duct system have a flame spread classification of 200 or less.

6.Non-combustiblepans having one-inch upturned flanges are located beneath openings in the floor return duct system.

7.Wiring materials located in the return duct system con- form to Article 300-22 (B&C) of the National Electrical Code (NFPA-70).

8.Gas piping is not run in or through the return duct sys- tem.

9.The negative pressure in the closet as determined by test with the air-circulatingfan operating at high heating

speed and the closet door closed is to be not more nega- tive than minus 0.05-inch water column.

10.For floor return systems, the manufactured home manu- facturer or installer shall affix a prominent marking on or near the appliance where it is easily read when the ctoset door is open. The marking shall read:

_WARNING

HAZARD OF ASPHYXIATION, DO NOT COVER OR RESTRICT FLOOR OPENING

AIR DISTRIBUTION SYSTEMS

For proper air distribution, the supply duct system shall be designed so that the static pressure does not exceed the listed static pressure rating on the furnace rating plate.

Three typicaldistdbution systems are illustrated in Figure 2.

Location, size and number of registers should be selected on the basis of best air distribution and floor plan of the home.

The Air Temperature Rise is to be adjusted to obtain a tem- perature dse within the range(s) specified on the furnace rat- ing plate.

A
Singletrunk duct _	C

E		TransitionDuct withBranches
	B*
		Transitionduct
	Dualtrunk duct with crossoverconnector

Dualtrunk duct

Crossover

I

_r-.. 3

1.CrossoverDuct must becentereddirectlyunder furnace.

2.Use 12" DiameterRound or insulatedFlex-duct only.

3.TerminateFlex-duct(oppositefurnace) in the centerof the trunk duct.

4.Flex_uct matedalmust be pulledtight-- No Loops or unnecessarydips-- Air Flow may be impeded.

FIGURE 2 : Air Distribution Systems

4 Unitary Products Group