ECR Dunkirk Q95M-200, Installation, Operation & Maintenance Manual

8 - COMBUSTION AIR AND VENT PIPE

Allowable Vent and Air Intake Lengths

3” Pipe Min. Length

3” Pipe Max. Length

15 ft. equivalent length

100 ft. equivalent length

FIELD INSTALL 2” BY 3”

 TRANSITION IN THE 

VERTICAL POSITION 

ONLY (2 REQ’D, NOT 

FURNISHED)

3”  INTAKE AND 

EXHAUST 

TERMINATIONS

2” (50.8MM) 

CPVC

 VENT PIPING

 (FURNISHED &

 REQUIRED)

2” (50.8MM) 

COMBUSTION AIR 

INTAKE PIPING 

(FURNISHED)

Figure 4 - Combustion Air & Vent Piping

9. 

Combustion air must be clean outdoor air. Do not take 

combustion air from inside structure because that air 

is frequently contaminated by halogens, which includes 

fluorides, chlorides, phosphates, bromides and iodides. 

These elements are found in aerosols, detergents, 

bleaches, cleaning solvents, salts, air fresheners, paints, 

adhesives, and other household products.

10. 

Locate combustion air inlet as far away as possible from 

swimming pool and swimming pool pump house.

11. 

 All combustion air and vent pipes must be airtight and 

watertight. 

12. 

Pitch exhaust air piping back to boiler at minimum ¼” per 

foot from vent terminals so all moisture in vent piping 

drains to boiler. Pitch pipes with no sags or low spots 

where moisture can accumulate and block flow of flue gas. 

13. 

Vent connections serving appliances vented by 

natural draft shall not be connected into any portion 

of mechanical draft systems operating under positive 

pressure.

8.2 Vent/Air Intake Termination Location

Consider following when determining appropriate location 

for termination of combustion air and vent piping. 

A. Position termination where vent vapors will not 

damage plants/shrubs, air conditioning equipment, or 

siding on the house.

B. Position termination so it will not be effected by wind 

eddy, air born leaves, snow, or recirculated flue gases.

C. Position termination where it will not be subjected to 

potential damage by foreign objects, such as stones, 

balls, etc.

D. Position termination where vent vapors are not 

objectionable.

E.  Put vent on wall away from prevailing winter wind. 

Locate or guard vent to prevent accidental contact 

with people or pets.

F.  Terminate vent above normal snow-line. Avoid locations 

where snow may drift and block vent. Ice or snow may 

cause boiler to shut down if vent becomes obstructed.

G.  Under certain conditions, flue gas will condense, 

forming moisture, and may be corrosive. In such 

cases, take steps to prevent building materials at 

vent from being damaged by exhaust of flue gas.

H.  United States - Terminate vent system at least 4 

feet (1.22 m) horizontally from, and in no case 

above or below, unless a 4 feet (1.22 m) horizontal 

distance is maintained, from electric meters, gas 

meters, regulators and relief equipment.

I.  Canada - Terminate vent system at least 6 feet 

(1.83m) horizontally from, and in no case above 

or below, unless 6 feet (1.83m) horizontal distance 

is maintained, from electric meters, gas meters, 

regulators and relief equipment.

J.  Terminate venting system at least 3 feet (0.3m) 

above any forced air inlet (except boiler’s 

combustion air inlet) within 10 feet (3m). 

K.  Terminate venting system at least 12 inches 

(300mm) from any air opening into any building. 

L.  Locate bottom of vent at least 12 inches (300mm) 

above grade. 

M.  Terminate vent not less than 7 feet (2.1m) above 

adjacent public walkway. 

N.  Vent terminal shall not be installed closer than 3 feet 

(0.9m) from inside corner of L shaped structure.

O.  Termination of vent should be kept at least 3 feet 

(0.9m) away from vegetation. 

P.  If multiple terminations are used, minimum of 

12 inches (300 mm) between exhaust of one 

termination and air intake of next termination. See 

pages 14 & 15.

Q.  All field installed vent pipe must be 3”.

Length of pipe is counted from end of supplied 2” CPVC 

pipe exiting boiler. Termination is not counted in “Total 

Equivalent Length.”
Reduce maximum vent/air intake length by 5 feet per each 

90° elbow.

WARNING

Covering non-metallic vent pipe and fittings with 

thermal insulation shall be prohibited.

!

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