Monessen Hearth DBX24C DFX & DBX Series Vent Free Fireplaces, COMBUSTION and VENTILATION AIR

DFX & DBX Series Vent Free Fireplaces COMBUSTION and VENTILATION AIR

ADEQUATE COMBUSTION AND VENTILATION AIR

This heater shall not be installed in a confined space or unusually tight construction unless provisions are provided for adequate combustion and ventilation air.

The National Fuel Gas Code, (ANSI Z223.1/NFPA54), defines a confined space as a space whose volume is less than 50 cubic feet per 1,000 BTU per hour (4.8 m3 per kw) of the aggre- gate input rating of all appliances installed in that space, and an unconfined space as a space whose volume is not less than 50 cubic feet per 1,000 BTU per hour (4.8 m3 per kw) of the aggregate input rating of all appliances installed in that space. Rooms communicating directly with the space in which the appliances are installed, through openings not furnished with doors, are considered a part of the unconfined space.

Unusually tight construction is defined as construction where:

a)walls and ceilings exposed to the outside atmosphere have a continuous water vapor retarder with a rating of 1 perm

(6 x 1011 kg per pa/sec-m2) or less with openings gasketed or sealed;

b)weather striping has been added on openable windows and doors, and

c)caulking or sealants are applied to areas such as joints around window and door frames, between sole plates and floors, between wall-ceiling joints, between wall panels, at pen- etrations for plumbing, electrical, and gas lines, and at other openings.

The following formula can be used to determine the maximum heater rating per the definition of unconfined space:

BTU/hr = (L1 + L2) Ft x (W) Ft x (H) Ft x 1000 50

Consider two connecting rooms with an open area between, with the following dimensions: L1 = 15Z\x Ft., L2 = 12 Ft., W = 12 Ft., H = 8 Ft.

BTU/hr = (15Z\x + 12) x (12) x (8) x 1000 = 52800 BTU/hr 50

If there were a door between the two rooms the calculation would be based only on the room with the heater.

BTU/hr =	(15Z\x) x (12) x (8)	x 1000 = 29,760 BTU/hr
	50

Room Divider

Fireplace

FP2439

H

W

Figure 3 -

Example of a Large Room with a Room

Divider

WARNING

If the area in which the heater may be operated is smaller than that defined as an unconfined space or if the building is of unusually tight construction, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA54, Section 5.3 or applicable local codes.

33D4047