Enerco MHU 75, MHU 45 C - Horizontal Venting - General, B - Vertical Vents Using Metal Vent Pipe

B – VERTICAL VENTS USING METAL VENT PIPE

–COMMERCIAL AND RESIDENTIAL INSTALLATIONS

MHU/HSU compact unit heaters are listed as Category I appliances for vertical vent installations.

1.MHU/HSU unit heaters are to be used with NFPA- or ANSI- approved chimneys, U.L. listed type B-1 gas vents, single wall metal pipe, or listed chimney lining system for gas venting where applicable, as well as the modifications and limitations listed in figure 2 . Seal single wall vent material according to the section A - General Recommendations and Requirements.

2.The vent connector shall be 3" (76mm) diameter on 45 unit and 4” (100mm) diameter for the 75 unit. In all cases, a flue transition piece (supplied) is required to fit over the outlet of the induced draft assembly on the appliance.

3.Keep the vent connector runs as short as possible with a minimum number of elbows. Refer to the (American) National Fuel Gas Code ANSI Z223.1 or (Canada) CSA B149.1 Natural Gas and Propane Installation Code for maximum vent and vent connector lengths. Horizontal run of the vent connector from the induced draft blower to the chimney/vent cannot exceed the values in table 2 .

4.When the length of a single wall vent, including elbows, exceeds 5 feet (1.5m), the vent shall be insulated along its entire length with a minimum of 1/2" thick foil faced fiberglass 1-1/2# density insulation. If a single wall vent is used in an unheated area it shall be insulated. Failure to do so will result in condensation of flue gases.

5.The unit may be vented vertically as a single appliance or as a common vent with other gas-fired appliances. In common venting situations, vent connectors for other appliances must maintain a 4" (100mm) vertical separation between the vent connectors. Refer to common venting tables in the(American) National Fuel Gas Code ANSI Z223.1 or (Canada) CSA B149.1 Natural Gas and Propane Installation Code for proper vent size.

6.Clearance to combustible material is 6" (152mm) for single wall vent material except where a listed clearance thimble

is used. Clearance to combustible material for type B-1 vent or factory-built chimney is per manufacturer’s instructions.

7.The vent connector shall be supported without any dips or sags. Vertical vents shall be supported in accordance with their listing and manufacturers’ instructions. All horizontal vent connector runs shall have a slope up to the vertical vent of at least 1/4" per foot (1mm per 50mm).

8.All vertical type B-1 vents, single wall vents, or listed chimney lining system must be terminated with a listed ventcap or listed roof assembly.

9.The vent must extend at least 3' (1m) above the highest point where it passes through a roof of a building and at least 2’ (0.6m) higher than any part of a building within a horizontal distance of 10' (3.05m) unless otherwise specified by the (American) National Fuel Gas Code, ANSI Z223.1 or (Canada) CSA B149.1 Natural Gas and Propane Installation Code.

The vent must extend at least 5' (1.6m) above the highest connected equipment flue collar.

C – HORIZONTAL VENTING – GENERAL

Common venting is not allowed when horizontally venting the unit heater.

The minimum horizontal vent length is three feet (914mm).

1.If possible, do not terminate the horizontal vent through a wall that is exposed to prevailing wind. Exposure to excessive winds can affect unit performance. If such a termination is necessary, use a wind block to protect the vent termination from direct wind.

2.Vent termination must be free from obstructions and at least 12" (306mm) above grade level and maximum snow height.

VENT TERMINATION ON SINGLE WALL VENT

SINGLE WALL TERMINATION

ROOF FLASHING

ROOF PITCHED

FROM 0” TO 45”

2” CLEARANCE

SHALL NOT BE ATHIMBLE CONCEALED SPACE

DOUBLE WALL (TYPE B-1) TERMINATION

ROOF FLASHING

ROOF PITCHED

FROM 0” TO 45”

12” MAX

CLEARANCE TO BE AS

SPECIFIED ON TYPE “B”

VENT PIPE

SEAL JOINT BETWEEN SINGLE WALL VENT

AND “B”VENT AND THE ANNULAR SPACE OF THE “B” VENT

FIGURE 2

3.Do not terminate vent directly below roof eaves or above a walkway, or any other area where condensate dripping may be troublesome and may cause some staining. Avoid windows where steam may cause fogging or ice buildup.

4.When horizontally vented, minimum clearance for termination from any door, window, gravity air inlet, gas or electric meter, regulators, and relief equipment is 4 ft. (1.2m) for U.S. installations. Refer to NFPA 54/ANSI Z223.1 in the U.S.A. and CSA B149.1 Natural Gas and Propane Installation Code

in Canada or with authorities having local jurisdiction. In Canada, vent termination must have a minimum 6 ft. (1.8mm) horizontal clearance from gas and electric meters and relief devices as specified in the CSA B149.1, Natural Gas and Propane Installation Code.

Enerco Compact Unit Heater 6 Operating Instructions and Owner’s Manual