Mr. Heater MHT 45 owner manual BASIC FLUE VENTING Residential Only, A. Single Heater Venting

BASIC FLUE VENTING (Residential Only)

•Venting must be in compliance with the latest edition of the National Fuel Gas Code (ANSI. Z223.1 latest edition: or the authority having jurisdiction.

•Uninsulated single-wall metal pipe shall not be used outdoors in cold climates for venting of these heaters as specified by Section 7.8 of the ANSI Z223.1/NFPA 54 National Fuel Gas Code-latest edition.

•For the installation of a single-wall metal pipe through an exterior combustible wall, refer to the latest edition of the National Fuel Gas Code or the authority having jurisdiction.

•In regions of the country where prevailing winds are consistently higher than 40 mph, it may be necessary to terminate the vent system above the roof level.

Other venting references can be found in equipment volume of the ASHRAE Handbook.

A. SINGLE HEATER VENTING

a) Vertical Through the Roof

NOTE: For residential applications, the heater must not be connected to a separate chimney, but must be installed using the venting system as specified below.

1. When venting the heater to outside of building through a roof,

use 3 inch O.D. single-wall metal pipe. This is to be constructed

The seams along the length of the piping and the joints between sections of piping should be sealed to prevent a potential leakage of flue gas into building. Use 100% RTV Silicone Rubber Adhesive sealant suitable for 500°F.

6.All portions of the vent pipe shall be supported to prevent from sagging.

7.When the vent pipe passes through areas where the ambient temperature is likely to induce condensation of the flue gasses, the vent pipe should be insulated and a condensation drain should be provided.

8.The minimum clearance to combustible materials for single- wall flue pipe shall be 6 inches. This may be reduced when the combustible material is protected as specified in the National Fuel Gas Code or the authority having jurisdiction.

9.Single-wall metal pipe shall not originate in any unoccupied attic or concealed space and shall not pass through any attic, inside wall or concealed space, or through any floor.

10.A venting system shall terminate at least 3 feet (0.9m) above any forced air inlet located within 10 feet (3.1m).

Vent Cap

(Leslie VersaCap)

Type B

	2' Min.		2' Min.
	2' Min.		(when no wall or
10'	(when no wall or		parapet exist)
	parapet exist)
or less
	Flashing
	2" Clearance Thimble
	Seal joint &	4"
		Vent
	annular space.
		Dia.	Total Vent
				¼ per ft. rise
			Height

of galvanized sheet metal or other approved noncombustible,

corrosion-resistant material as indicated by state and/or local

VERTICAL

(5' Min.)

codes.

2. A vent passing through a combustible roof shall extend through

a 2-inch 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 (such as Leslie “VersaCap” Type

B) must be attached to the 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.

Minimum Equivalent Length = 5 feet of Pipe

Maximum Equivalent Length = 25 feet of Pipe

Use the following correction factors to obtain the equivalent

length:

a) Subtract 15 feet if the run is horizontal.

b) Subtract 10 feet for an approved vent cap.

c) Subtract 10 feet for each elbow beyond 15 feet from the

heater.

d) Subtract 15 feet for each elbow within 15 feet of the heater.

4. Limit the quantity of 90° elbows to two. When vent pipe is in a

horizontal run, it must rise not less than ¼ inch per foot from

the start of the vent system towards the vent terminal.

5. Joints between sections of piping shall be fastened by sheet

metal screws or other approved means.

THROUGH THE ROOF

Lateral

SINGLE HEATER VENTING

b)Vent Termination (Residential Installations)

1.The vent terminal shall terminate above the roof line so that no discharge opening is less than 2 feet (0.6m) horizontally from the roof surface. The lowest discharge opening will be no closer than the minimum height specified in the following table. These minimum heights may be used provided the vent is not less than 8 feet (2.4m) from any vertical wall or similar obstruction.

Not less than 8ft.

2ft. min.

H (Min.)

Vertical Wall

a) Be sure that method selected for venting heater complies with all

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