Slant/Fin Oil-fired Boiler dimensions Requires AIR from OUT

4 INTREPID

Any oil-fired boiler must have a steady draft* and an ample supply of combustion air at all times during firing. If air supply or chimney draft* is unreliable, CO2 and overfire draft* will change unpredictably.

DO NOT vent this boiler to the same chimney flue used by a fireplace or coal or wood burning furnace or boiler. The draft* produced by solid fueled devices varies tremendously between high fire and low fire:

In modern, weather stripped, energy-saving buildings or older buildings which have been modified similarly, natural infiltration may not supply enough air for combustion, particularly if other fuel burning appliances, exhaust fans or draft inducers are competing for the same air supply. Fireplaces, other solid fuel burning appliances and exhaust fans con- sume great quantities of air; if air supply is not ample, such an appliance will create a downdraft in the oil-fired boiler flue. This can create a haz- ardous condition. Flue gases can be sucked out of the chimney through

the vent regulator into the living space. DO NOT operate this boiler and a solid fuel burning appliance at the same time, unless the solid fuel burner is provided with its own outside air supply.

See Table 2, “Provisions for Combustion and Ventilation Air Supply” for determining need and method of providing air for combustion and ventilation.

If fly screen must be used over air supply openings, areas calculated should be doubled; the screen should be inspected and cleaned fre- quently to maintain free air flow.

Protect air openings against closure by snow, debris, etc. Openings such as doors or windows, if used, must be locked open.

* Draft is negative or suction pressure

TABLE 2: Provisions for Combustion and Ventilation Air Supply. See NFPA 31, latest edition for more detailed information.

	Boiler Location	Air Supply	Action Required
2.1	Unconfined space	Is there sufficient air for combus-	NONE
		tion by natural infiltration (see
		NOTE (1), “Test...” below)?
2.2	Unconfined space	If there is NOT sufficient air for	Provide air from outdoors directly through a permanent outside
		combustion by natural infiltration	wall opening or openings with a free open area of not less than
		due to tight construction or other	1 sq. in. per 4000 Btu/hr of TOTAL input of ALL fuel burning
		conditions, then it REQUIRES AIR	appliances in the building. See Note (1) and (3).
		FROM OUTDOORS. SEE
		“ACTION REQUIRED” column at
		right. See Notes (1) and (2) below.
2.3	Confined space	If there is sufficient air for combus-
		tion from within building but it	The confined space shall be provided with two permanent air
		comes from outside of the	openings, one near the top of the enclosure and one near the
		confined space. SEE “ACTION	bottom. EACH opening shall have a free air opening of not less
		REQUIRED” column at right.	than 1 sq. in. per 1000 Btu/hr. of TOTAL input of ALL fuel burning
		See Note (1) below.	appliances within the enclosure. The two openings shall freely
			communicate with the interior areas of the building which in turn
			would have to have adequate infiltration of air from outdoors.
			See Notes (1, 3) and Figure 3a.
2.4	Confined space	If there is NOT sufficient air for	(a) Air from the outdoors shall be provided to the confined space
		combustion due to tight construc-	by two permanent openings, one in or near the top of the
		tion or other conditions it	enclosure space and one in or near the bottom. The open-
		REQUIRES AIR FROM OUT-	ings shall communicate directly, or by means of ducts, with
		DOORS. SEE “ACTION	outdoors or to such spaces (crawl or attic) that freely com-
		REQUIRED” column at right.	municate with outdoors (See figures 3b, 3c
		See NOTE (2) below.	and 3d).
			(b) Where directly communicating with outdoors or by means of
			vertical ducts, each opening shall have a free area of not
			less than 1 sq. in. per 4,000 Btu/hr. (35 sq. in. per gal. per hr.)
			of TOTAL input rating of ALL appliances in the enclosure. If
			horizontal ducts are used, each opening shall have a free
			area of not less than 1 sq. in. per 2,000 Btu/hr. (70 sq. in. per
			gal. per hr.) of TOTAL input of ALL appliances in the confined
			space. See Figures 3b, 3c and 3d.

(1)Test for sufficient air for combustion by infiltration by running this boiler for 30 minutes under all of the following conditions and at the same time: a) all doors, win- dows and other like openings must be closed, b) all fuel burning appliances should be FIRING, c) all exhaust fans and clothes dryers turned ON. At the above conditions the CO2, smoke and draft readings must be normal. (CO2 between 11% and 13%, smoke between ZERO and a TRACE, draft between .02” W.C. and

.04” W.C. negative pressure.)

(2)Aside from tight construction, some of the conditions that steal air for combustion from a boiler are other fuel burning appliances, exhaust fans and clothes dryers.

(3)Generally, louvers made of wood have a free open area of 20% and those made of metal have a 60% to 70% free open area. Screens also reduce the open area of the louvers.