User Guide
page 8
PROPERLY SETTING THE AIRFLOW ADJUSTMENTS ON THE POWER VENTER AND DRAFT CONTROL
1. Set the adjustment damper in the SWG venter to its full open position.
2. Start with no weights on the chain hanger of the MG-1 draft control.
3. Follow the appliance manufacturer's procedures for starting the heating appliance. Then adjust the
thermostat to call for HEAT.
4. After the system has operated for at least 10 minutes to stabilize ue gas temperatures, check for
negative draft or up-draft at the heating appliance outlet. Use a draft gauge, velocity meter or match
test procedure.
5. Loosen the damper locking screw on the underside of the SWG outer pipe and rotate the adjustment
damper closed to obtain the minimum air ow required to maintain draft. Then increase air ow slightly
(10% over minimum air ow rate) to ensure proper venting. If using a draft gauge, draft settings should
typically be -0.02" of water column draft at the appliance outlet. (Check equipment requirement.)
6. Observe the position of the gate on the draft control. It should be set so that during normal operation the
gate is in the midpoint of its swing. This will be approximately 30º - 45º from vertical.
7. When rst setting up the system the gate on the control will probably be fully open. Add washer weights
to the chain hanger until the gate stabilizes at the midpoint of its swing.
8. Changing the weight on the draft control will aect the system draft, therefore repeat steps 5 through 7
as necessary until proper draft is obtained and the draft control gate is in the proper position.
9. Tighten the damper locking screw on the SWG to prevent it from moving during operation and secure the
washer weights on the draft control with the provided screw and nut.
Figure 13
WHILE ADJUSTING THE SYSTEM AIRFLOW, TWO THINGS ARE ESSENTIAL
1. The appliance burner must operate for at least 10 minutes prior to setting the draft to stabilize ue gas
temperatures.
2. An analysis of the ue gases is necessary to determine the percentage of CO
2
and check for the
presence of CO. Refer to the local gas company for the proper CO
2
readings and allowable CO levels.
Refer to the General Installation Inspection section to check for negative pressure problems in the building.
If sucient combustion air for the burner is not provided, a ow reversal during the o cycle could occur
within the venting system. This may cause combustion problems as well as condensation that could block
the air pressure sensing tube. It may also contribute to premature motor failure. Combustion, and/or makeup
air, should be supplied from outside the structure and the air inlet should be on the same wall as the power
venter discharge. For example, tightly constructed homes and homes retrotted from electric heated systems
are more likely to experience combustion and/or makeup air problems. For further information consult Form
#4199, “The Field Report - Eects of Insucient Combustion Air” available from Field Controls.
or removing the washer-like weights (supplied with the
control) to or from the weight holder chain assembly. After
the control is adjusted, its action will be entirely automatic,
the gate will open or close by itself to correct for changes
in the draft. The control MUST be adjusted to the desired
draft setting by adding or removing the washer-type
weights supported by the two chains on the side of the
draft control. (See Figure 13) DO NOT move the weight
attached directly to the gate, this is used only for balancing
at the factory.