Weil-McLain 550-141-850/0599 manual Special considerations, GV in small space less than alone

•Installation • Start-Up • Parts • Maintenance

GV in small space (less than Fig. 1) — alone

For all vent/air situations, whether air is taken from inside or outside, provide two openings, each with minimum free area of:

1 square inch per 1,000 Btuh of GV input.

The openings must be within 6 inches of the ceiling and 6 inches of the floor as shown in Figure 2 for small space installations.

use inside air for combustion and ventilation.

Exhaust fans and air movers

The appliance space must never be under a negative pressure, even if the appliance(s) are installed as direct vent. Always provide air openings sized not only to the dimensions required for the firing rate of all appliances, but also to handle the air movement rate of the exhaust fans or air movers using air from the building or space.

Special considerations

Tight construction

ANSI Z223.1 defines unusually tight construction where:

a.Walls and ceilings exposed to the outside atmosphere have a continuous water vapor retarder with a rating of 1 perm or less with openings gasketed, and . . .

b.Weatherstripping has been added on openable windows and doors, and

. . .

c.Caulking or sealants are applied to areas such as joints around windows and door frames, between sole plates and floors, between wall-ceiling joints, between wall panels, at penetrations for plumbing, electrical, and gas lines, and in other openings.

For buildings with such construction, provide air openings into the building from outside, sized per the appropriate case in Figure 3 if appliances are to

Motorized air dampers

If the air openings are fitted with motorized dampers, electrically interlock the damper to:

•Prevent the boiler from firing if the damper is not fully open.

•Shut the boiler down should the damper close during boiler operation.

To accomplish this interlock, wire an isolated contact (proving the damper open) in series with the thermostat input to the boiler. The boiler will not start if this contact is open, and will shut down should it open during operation.

Figure 3

Air openings: GV in space with other appliances

a—

Air from inside building

b—

Air directly from outside

c—

a		0 to 12"
	Each opening free area =		Air opening
	1 sq. inch per 1,000 Btuh
			Add air openings
			to outside if
			building is tight
Other	Flue	Air (direct vent)	construction.
appliances
	GV	(optional)
			Air opening
		Air
		0 to 12"
85005		Outside or ventilated attic

b Each opening free area = 1 sq. inch per 4,000 Btuh

Other	Flue	Air (direct vent)
appliances
	GV	(optional)
		Air

0 to 12"

Air	opening Outside
Air	opening

0 to 12"

Air through vertical ducts (or inlet air from ventilated crawl space)

d—

Air through horizontal ducts

c	Each opening free area =
	1 sq. inch per 4,000 Btuh
Other	Flue	Air (direct vent)
appliances
	GV	(optional)
		Air
		12" — or —

Ventilated

crawl space

d			0 to 12"	Air opening
	1 sq. inch per 2,000 Btuh
	Each opening free area =
	Other	Flue	Air (direct vent)	Outside
appliances
		GV	(optional)
				Air opening
			Air
			0 to 12"

Part number 550-141-850/0699 15