Weil-McLain 550-110-260/02002 1e Prepare boiler location — air openings, Sizing air openings

GOLD CGs Gas-Fired Water Boiler

1e Prepare boiler location — air openings

CGs combustion air options	Louver allowance
Using inside air — direct exhaust vent	The free area of openings means the area after
The CGs boiler can use inside air if no contaminants	reduction for any installed louvers or grilles. Be sure
	to consider this reduction when sizing the air openings.
are present in the boiler space. If contaminants are likely
to be present, install the CGs boiler as a direct vent
appliance, using the appropriate vent supplement and
the instructions in this manual.

Using outside air — direct vent

Combustion air can be ducted directly from outside to the CGs boiler air intake fitting. This method is defined as direct vent (also referred to as sealed combustion). Refer to the appropriate vent supplement and the instructions in this manual. Two options are available: sidewall or vertical direct vent. Each requires a special vent component kit.

Sizing air openings

Air openings provide for ventilation (as well as combustion air) to prevent overheating of the boiler controls and boiler space. Air is also needed for other appliances located in the same space.

Use Figure 3, selecting the appropriate installation conditions. Note that the sizing given in Figure 3 applies only to CGs installations with clearances no smaller than shown in Figure 1, page 7 of this manual. For smaller clearances, regardless of how the air openings are arranged, two openings providing free area of 1 square inch per 1,000 Btuh input of all appliances in the space are required.

Air openings must be sized to handle all appliances and air movers (exhaust fans, etc.) using the air supply.

The sizing given in Figure 3 is based on the National Fuel Gas Code, ANSI Z223.1, allowing adequate air opening for gravity-vented gas appliances (Category I). The CGs boiler is rated Category III or IV (pressurized vent), and has different requirements for combustion and ventilation air, reflected by the special sizing instructions given in Figure 3. The air openings recommended in Figure 3 will allow adequate ventilation and combustion air provided the boiler room is not subjected to negative pressure due to exhaust fans or other mechanical ventilation devices. Refer to the National Fuel Gas Code for dealing with other conditions.

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.Weather-stripping 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 use inside air for combustion and ventilation.

Exhaust fans and air movers

The appliance space must never be under a negative pressure unless all appliances 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.

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.

10 Part number 550-110-260/0200