Draft Control D R A F T C O N T R O L G U I D E w w w . f i e l d c o n t r o l s .
Draft Control For proper operation and efficient fuel consumption in oil, gas, and/or coal-fired heating appliances, draft must remain constant. When it is, combustion is more complete, fuels are utilized efficiently, and money is saved. RC MG-1 Field Draft Controls maintain consistent draft by counteracting the negative forces caused by changes in temperature and barometric pressure, as well as the effects of wind.
Draft Control Typical Natural Vent System Illustration B demonstrates how pressure changes as air/gases flow through the appliance (A), past the draft control (B), through the vent pipe (C), and outside the building (D/E). Illustration B When to use a Draft Control • Draft Inducers/Power Venters With these devices, draft is increased or created, causing fluctuations in air flow through the combustion chamber.
Draft Control Type RC Oil or Coal – Residential and Commercial The Field RC is furnished as standard equipment on many leading brands of oil or coal-fired heating equipment. It is calibrated to allow for easy adjustment to the furnace or boiler manufacturer’s specifications. Designed for settings from .02" to .08", this control is so sensitive that instrumentation should be used when adjusting the unit during installation.
Draft Control Type M Oil or Coal - Residential The M control lends itself ideally to conditions requiring a great deal of stability and accuracy. Designed for settings from .01" to .1", the Field M Control is recommended for oil or coal-fired residential heating applications. The Type M features an infinitely variable screw adjustment, permitting an extremely fine instrument setting.
Draft Control Type M+MG2 Solid, Oil or Gas Commercial/Industrial This is a series of compact, rugged, heavy-duty controls for use on large residential, commercial, and industrial applications. The Field Type M+MG2 Draft Control provides precise draft regulations for solid fuels, oil, gas, or oil/gas appliances requiring only the simplest, on-thejob adjustments depending on which fuel is to be utilized.
Draft Control (Installation Options) Recommended Locations for Field Draft Controls For gas-fired equipment, the preferred location of the control is on the bull head tee. This location provides maximum relief of downdrafts with minimum positive pressure. (See Fig. 1, Dia. A-C) Fig. 1 With oil or solid fuels, the bull head tee is not recommended, so locate the control as shown. (See Fig. 1, Dia. D-J) These locations are acceptable for gas units as well.
Draft Control (Sizing the Control) Choosing The Right Size Simple rules of thumb to guide size selections: 1. For most applications, the draft control should be the same size as the flue pipe. In other words, use a 6" control for a 6" pipe. 2. If the flue pipe or breaching is square, use the round equivalent. For example - on a 14" x 14" breaching use a 14" control. Little flow occurs in the corners of a square pipe, so its capacity is approximately the same as a round pipe of the same diameter. 3.
Draft Inducers Field Draft Inducers solve the drafting problems caused by short chimneys, undersized flue pipes and negative building pressures. Draft Inducers are designed for easy installation in a wide variety of applications, including oil or gas-fired furnaces, water heaters, and boilers. For venting single or multiple appliances, use a control kit. DI Paks are available for 24 volt and millivolt applications and include all controls necessary. Note: Pressure switch required according to NFPA code.
Draft Inducers Sizing Chart Gas-Firing with Draft Hood Input (BTU/HR) Gas-Firing with Barometric Draft Control Static Pipe Flow Draft Inducer Pressure Dia. (CFM) (Model) (IN W.C.) (IN) 69,000 105,000 111,000 120,000 3 4 5 6 279,000 308,000 330,000 353,000 5 6 7 8 522,000 674,000 694,000 835,000 8 9 10 12 900,000 1,250,000 1,400,000 1,800,000 10 12 14 16 2,000,000 2,200,000 2,400,000 2,800,000 14 16 18 20 Oil or Coal-Firing with Barometric Draft Control Static Pipe Flow Max.
(For Wood/ Coal Fireplaces) Chimney Top Draft Inducer The Type C Chimney Top Draft Inducer provides negative pressure to overcome the effects of wind, cold chimneys, insufficient chimney height, and downdraft. The Type C Draft Inducer is effective when venting standard fireplaces and freestanding gas fireplaces. The Type C Draft Inducer is available in four sizes: 6", 8", 10", and 13", and is designed to provide years of trouble-free operation.
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