Form #43343530
–34– JJuly 08
Failure to do so may result in death, serious injury, property damage or illness
from Carbon Monoxide poisoning.
Heaters installed in an unvented mode require a minimum ventilation flow of
4 CFM per 1,000 Btu/hr of total installed capacity.
In buildings with airborne contamination such as poultry houses the heater
must be installed with fresh air for combustion.
CARBON MONOXIDE HAZARD
A. BASIC FLUE VENTING — Venting must comply with the latest edition of the National Fuel Gas Code (ANSI
Z223.1-latest edition) or the authority having jurisdiction. Other venting references are in the equipment volume of
the ASHRAE Handbook.
Vent lengths shown in the table are for horizontal and vertical venting. If a longer length of vertical or horizontal
venting is required contact the manufacturer for assistance with vent sizing.
SINGLE HEATER VENTING (VERTICAL THROUGH THE ROOF)
1. When venting the heater to outside of building through a roof, use single-wall metal pipe. This is to be
constructed of galvanized sheet metal or other approved noncombustible corrosion-resistant material as
allowed by state or local codes.
2. A vent passing through a combustible roof shall extend through an approved clearance roof thimble.
Double-wall, Type B vent must be used for the portion of the vent system which passes through the roof. An
approved vent cap (Leslie “VersaCap”-Type B or equal) must be attached to end of the flue.
3. The maximum equivalent length of vent pipe should be carefully observed. A safety switch in the heater is
designed to shut the heater off before excessive flue restriction causes bad combustion. Refer to the Vent
Sizing Table for maximum vent lengths and vent pipe diameter.
4. Joints between sections of piping shall be fastened by sheet metal screws or other approved means and
should be sealed to prevent leakage of flue gas into building. Aluminum or Teflon tape suitable for 550ºF
(3M Company tapes 433 or 363) or silicone sealant is recommended.
5. All portions of the vent pipe shall be supported to prevent from sagging (6’ spacing is recommended).
6. When the vent pipe passes through areas where the ambient temperature is likely to induce condensation of
Model Heat
exchanger
length ft
Maximum vent length ft.
(4” diameter)
Maximum Fresh air
intake length ft (4”
diameter)
Max. combination of
fresh air and vent ft. (4”
diameter)
PTS/U 40/25 20 45 50 75
PTS/U 50/30 20 45 50 75
PTS/U 50/30 30 35 40 65
PTS/U 75/50 20 45 50 75
PTS/U 75/50 30 35 40 65
PTS/U 100/65 30 45 50 75
PTS/U 100/65 40 35 40 65
PTS/U 125/80 30 60 50 75
PTS/U 125/80 40 50 40 65
PTS/U 125/80 50 40 30 55
PTS/U 150/100 40 60 50 75
PTS/U 150/100 50 50 40 65
PTS/U 150/100 60 40 30 55
PTS/U 175/110 50 60 50 75
PTS/U 175/110
60 50 40 65
PTS/U 175/110
70 40 30 55
PTS/U 175/110
50 60 40 65
PTS/U 200/125 60 50 30 55
PTS/U 200/125
70 40 30 45