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Silver cylindrical HVAC draft control unit with adjustable weight mechanism

Field Controls

Field Controls 46198901 4MG1 4" MG1 Barometric Draft Control For Gas Applications hvac control

SKU CH-7CCK-8GT3W

Double-acting barometric draft control for gas furnaces and boilers, adjustable from .01" to .1"

  • ColorSilver
  • Precise draft regulation for gas appliances
  • Double-acting design relieves positive vent pressure
  • Adjustable weights allow 0.01" to 0.1" draft settings
  • Suitable where standard draft hoods cannot fit
  • Improves combustion stability on problematic venting systems

HVAC control for gas appliances

The Field Controls 46198901 4MG1 is a double-acting barometric draft control built for gas-fired furnaces and boilers. It suits conversion burner installations, draft-induced appliances with mechanical inducers, and sidewall power venters. Installers also use it on atmospheric gas appliances where a draft hood cannot be fitted.

Thermals noise and power draw

The device operates passively without electrical consumption or moving fans, so it adds no noise or power draw to the system. It regulates draft by opening outward to relieve positive vent pressures as low as .01 inches water column. Adjustable weights provide stable control between .01 and .1 inches water column for consistent combustion.

Bundled accessories and software

The unit ships as a single 4-inch MG1 control body in a silver finish with the weight adjustment mechanism integrated. No separate software, wiring harnesses, or mounting brackets are included in the package. The installer supplies vent piping and fasteners appropriate to the specific appliance and vent configuration.

Highlights

  • Precise draft regulation for gas appliances
  • Double-acting design relieves positive vent pressure
  • Adjustable weights allow 0.01" to 0.1" draft settings
  • Suitable where standard draft hoods cannot fit
  • Improves combustion stability on problematic venting systems

Specifications

BrandField controls
ColorSilver

Questions about this item

How do I install the 4MG1 barometric draft control and which step is most often missed?

Mount the 4MG1 in the vent connector with the hinge horizontal and the arrow pointing in the direction of flue-gas flow; the step most often missed is setting the adjustable weight to the required draft pressure between .01 and .1 inches water column after the unit is levelled.

What maintenance or replacement will the 4MG1 need over time?

Inspect the damper hinge and weight mechanism annually for soot buildup or corrosion; clean the pivot points and verify free movement, and replace the control if the damper no longer seals or the weight adjustment slips.

What is the first limit that appears on the 4MG1 during sustained high-draft operation?

The damper reaches its maximum open position and can no longer increase relief once the draft pressure exceeds the upper adjustment limit of .1 inches water column.

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