Suspension Methods; General Venting And Combustion Air Instructions; Ansi Venting Requirements - Modine Manufacturing PSH Installation And Service Manual

Separated combustion high efficiency gas-fired unit heaters
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INSTALLATION
Figure 2

Suspension Methods

Remove Side Panels
to Adjust Mounting Brackets
Venting
General Venting and Combustion Air
Instructions
CAUTION
Gas-fired heating equipment must be vented — do not operated
unvented.
A built-in power exhauster is provided — additional external
draft hoods (diverters) or power exhausters are not required or
permitted.
Installation must conform with local building codes or in the
absence of local codes, with the National Fuel Gas Code, ANSI
Z223.1 (NFPA 54) — Latest Edition. In Canada installation must
be in accordance with CAN/CGA-B149.1 for natural gas
appliances, and CAN/CGA-B149.2 for propane appliances.
Table 1

ANSI venting requirements

Appliance
Category
Description
I
Negative vent pressure
Non-condensing
II
Negative vent pressure
Condensing
III
Positive vent pressure
Non-condensing
IV
Positive vent pressure
Condensing
1. Table 1 summarizes the ANSI venting requirements for the
various appliance categories. All PSH/BSH models are
category III appliances. The venting requirements for a
category III appliance are included in these instructions.
2. Select the size of vent and combustion air pipe that fits the
power exhauster and combustion air intake on the rear of
the appliance (see pages 14 and 15 for dimensions). Do
not use a vent or combustion air pipe smaller than the size
of the outlet or inlet on the appliance. The pipe should be
single wall galvanized steel or other suitable corrosion
resistant material. Follow the National Fuel Gas Code for
minimum thickness of vent material. The minimum
thickness for connectors varies depending on the pipe
diameter.
3. A minimum of 12 inches straight pipe is recommended from
the power exhauster outlet before turns in the vent pipe.
4
(Suspension w/ Pipe Adapter Kit)
Venting
Requirements
Follow standard venting
requirements.
Condensate must be
drained.
Vent must be gastight.
Vent must be liquid and
gastight.
Condensate must be
drained.
4. Install the vent and combustion air pipes with a downward
slope from the appliance of 1/4 inch per foot and suspend
securely from overhead structures at points no greater than
3 feet apart. Fasten individual lengths of vent together with
at least three corrosion resistant sheet metal screws.
5. Keep the vent pipe at least 6 inches from combustible
material. The minimum distance from combustible material
is based on the combustible material surface not exceeding
160F. Clearance from the vent pipe (or the top of the unit)
may be required to be greater than 6 inches if heat damage
other than fire (such as material distortion or discoloration)
could result.
6. Avoid venting through unheated space when possible.
When venting does pass through an unheated space,
insulate runs greater than 5 feet to minimize condensation.
Inspect for leakage prior to insulating and use insulation
that is noncombustible with a rating of not less than 350F.
Install a tee fitting at the low point of the vent system and
provide a drip let with a clean out cap as shown in figure
01. The drip leg should be cleaned annually.
7. When the vent passes through an INTERIOR wall or floor, a
metal thimble 4 inches greater than the vent diameter is
necessary. If there is 6 feet or more of vent pipe in the
open space between the unit heater and where the vent
pipe passes through the wall or floor, the thimble need only
be 2 inches greater than the diameter of the vent pipe. If a
thimble is not used, all combustible material must be cut
away to provide a 6 inches clearance. Any material used to
close the opening must be noncombustible.
8. Limit the total equivalent vent pipe length to a minimum of 5
feet and a maximum of 30 feet, making the vent system as
straight as possible. (The equivalent length of a 4 inch
elbow is 5 feet and a 6 inch elbow is 10 feet).
9. Seal the joints with a metallic tape suitable for temperatures
up to 350F. (3M tapes 433 or 363 are acceptable.) Wrap
the tape two full turns around the vent pipe.
10. Do NOT vent this appliance into a masonry chimney.
11. Do NOT use dampers or other devices in the vent or
combustion air pipes.
12. The venting system must be exclusive to a single appliance,
and to other appliance is allowed to be vented into it.
13. Long runs of horizontal or vertical combustion air pipes may
require insulation in very cold climates to prevent the
buildup of condensation on the outside of the pipe where
the pipe passes through conditioned spaces.
14. Vertical combustion air pipes should be fitted with a tee with
a drip leg and a clean out cap to prevent against the
possibility of any moister in the combustion air pipe from
entering the unit. The drip leg should be inspected and
cleaned periodically during the heating season.
15. When condensation may be a problem, the vent system
shall not terminate over public walkways or over an area
where condensate or vapor could create a nuisance or
hazard or could be detrimental to the operation of regulator,
relief openings or other equipment.
16. Precautions must be taken to prevent degradation of
building materials by flue products.
17. The vent cap for vertically vented appliances should extend
above any portion of a building within a horizontal distance
of 2 feet. Refer to figures 7 and 8.
Heater Parts from ACF Greenhouses

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