Raypak 0066B manual Venting Connections, Model No Vent Max Connector Horizontal Diameter Length ft

Location of the openings is the same as in the previ- ous case - that is, within 12" of the top, and within 12" of the bottom of the enclosure. If horizontal ducts are used, the area must be doubled and the duct area shall not be less than the area of the openings they connect, and in no case shall the smallest dimension be less than 3".

Venting Connections

These boilers have built-in drafthoods. Vent piping the same size or larger than the drafthood outlet is recom- mended; however, when the total vent height (drafthood outlet to vent terminal) is at least ten (10) feet, the vent pipe size may be reduced by one size only as specified in the latest edition of the National Fuel Gas Code, ANSI Z223.1.

As much as possible, avoid long horizontal runs of vent pipe and too many elbows. If installation requires horizontal runs, the vent pipe must have a minimum of 1/4 inch per foot rise and should be supported at not less than five foot intervals. Maximum vent connector horizontal length shall be 1-1/2 feet (18 inches) for each inch of connector diameter as shown in Table E.

Model No.	Vent	Max.
	Connector	Horizontal
	Diameter (in.)	Length (ft)
0042	4	6
0066, 0090	5	7.5
0135	6	9
0180	7	10.5

Table E: Maximum Horizontal Length of Vent Pipe

Gas vents supported only by the flashing and extend- ing above the roof more than five feet should be securely guyed or braced to withstand snow and wind loads. We recommend use of insulated vent pipe spacer through the roofs and walls.

For protection against rain or blockage by snow, the vent pipe must terminate with a listed vent cap which complies with the local codes or, in the absence of such codes, to the latest edition of the National Fuel Gas Code, ANSI Z223.1.

The discharge opening must be a minimum of two (2) feet vertically from the roof surface and at least two (2) feet higher than any part of the building within ten (10) feet. Vent stack shall be at least five (5) feet in vertical height above the drafthood outlet.

The vent cap location shall have a minimum clearance of four (4) feet horizontally from, and in no case above or below, unless a 4-foot horizontal distance is main- tained, from electric meters, gas meters, regulators and relief equipment.

The weight of the vent stack or chimney must not rest on the boiler's drafthood. Support must be provided in compliance with applicable codes. The boiler top and drafthood must be readily removable for maintenance and inspection. Vent pipe should be adequately sup- ported to maintain proper clearances from combustible construction.

Type "B" double-wall (or equivalent) vent pipe is rec- ommended. However, single-wall metal vent pipe may be used as specified in the latest edition of the National Flue Gas Code ANSI Z223.1.

Lowest Discharge

Opening

Listed Cap

Listed Gas Vent

X

12

Roof Pitch is X/12

H - Minimum Height from

Roof to Lowest

Discharge Opening

Refer to Table F for detailed information

Fig. 4: Minimum Height from Roof to Lowest Discharge

Opening

9