Heatiator GDST3831I Constructing the Appliance Chase, Clearances, Minimum Framing Dimensions

B. Constructing the Appliance Chase

A chase is a vertical box-like structure built to enclose the gas appliance and/or its vent system. In cooler climates the vent should enclosed inside the chase.

NOTICE: Treatment of ceiling firestops and wall shield firestops and construction of the chase may vary with the type of building. These instructions are not substitutes for the requirements of local building codes. Therefore, you MUST check local building codes to determine the requirements to these steps.

Chases should be constructed in the manner of all out- side walls of the home to prevent cold air drafting prob- lems. The chase should not break the outside building envelope in any manner.

Walls, ceiling, base plate and cantilever floor of the chase should be insulated. Vapor and air infiltration barriers should be installed in the chase as per regional codes for the rest of the home. Additionally, in regions where cold air infiltration may be an issue, the inside surfaces may be sheetrocked and taped for maximum air tightness.

To further prevent drafts, the wall shield and ceiling fire- stops should be caulked with caulk with a minimum of 300ºF continuous exposure rating to seal gaps. Gas line holes and other openings should be caulked with caulk with a minimum of 300ºF continuous exposure rating or stuffed with unfaced insulation. If the appliance is being installed on a cement slab, a layer of plywood may be placed underneath to prevent conducting cold up into the room.

C. Clearances

NOTICE: Install appliance on hard metal or wood surfaces extending full width and depth. DO NOT install directly on carpeting, vinyl, tile or any combustible material other than wood.

WARNING! Risk of Fire! Maintain specified air space clearances to appliance and vent pipe:

•Insulation and other materials must be secured to prevent accidental contact.

•The chase must be properly blocked to prevent blown insulation or other combustibles from entering and making contact with fireplace or chimney.

•Failure to maintain airspace may cause overheating and a fire.

A

A

HEADER

*C

B

D

Note: The header must be installed on end as shown in this diagram.

E

F

I

G

H

MINIMUM FRAMING DIMENSIONS

	A	B	*C	D	E	F	G	H	I
GDST3831I	Rough	Rough	Rough	Rough	Clearance	Combustible	Combustible	Ends of	Sides of
	Opening	Opening	Opening	Opening
	(Width)	(Height)	(Depth)	(Width)	to Ceiling	Floor	Flooring	Appliance	Appliance
Inches	8-5/8	34-3/4	15	38-1/8	31	0	0	1/2	36
Millimeters	219	883	381	969	787	0	0	13	914

*Adjust framing dimensions for interior sheathing (such as sheetrock)

Figure 5.2 Clearances to Combustibles GDST3831I

Heatilator • GDST3831I • 2127-900 Rev. K • 7/12 19