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Re: one of my hvac dampers is stuck open
Zoned forced air systems that use multiple thermostats that can start a single heating and cooling unit from each stat and condition just that space that called it, are conditioned by the auto damper you are referring to. These dampers are normally spring closed and driven open using a small 24 volt motor (Called an Actuator or Operator) connected to the stat that operates the damper motor with a relay. Disconnect the damper crank arm and linkage between the damper and its motor and see if the damper rotates closed. See if the damper will move freely. Power and remove power from the motor to see if it works. Doing these things will probably find the problem. Good Luck. Roger
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Keep in mind you have the same terminals on the damper. 1-4-6. be sure both board and dampers are wired the same for spring open/power closed. I cant remember if that 311 sends power with a call or not( if power is being sent when light is on), but once you have double checked the damper wiring either verify with a meter that power is being sent or verify air flow. if it is then backwards simply reverse wires on board. I suspect it sends power when light is on, that is why zone 3 is lit. (there is no call for cooling on 3, therefore it is shutting the damper) YES, the damper that is not really there. Let me know, hope this helps. The damper that is trying to cool should NOT be getting any power, wire accordingly.
Be sure all zones are calling for cooling. Press the purge override and verify air flow on all zones. If one is still not working verify the board is sending voltage to that damper. A meter is a huge help but if all lights are on chances are the damper is stuck. You should be able to free it up but it will just happen again. Either replace damper motor, replace damper or if you can figure out if it is a "spring open" damper, get it open and unhook the wire to that zone. This will keep it open at all times because it can not "power close". Provided that zone CAN stay open all the time. Keep me posted!!
Choose two colors of the thermostat wire, and connect them to the NO and COM and connect them to the zone control board leads for the zone intended. Almost all zone valves spring return open when deenergized. So ensure the zone valve is open with the system is off. At the base of zone valve there is a set screw that needs to engage the damper valve shaft in the open position with the motor in the spring release position. Most zone valve are 90 degree moment from full open to full shut. If you have a Carrier zone valve, they go full open to full shut in 45 degrees of motion. Your open stop need to be set so the valve stops in the full stop position.
To help understand the operation of a zone system, say you have 2 zone system and zone 1 thermostat initiates a heat or cool demand. Zone 2 valves energizes and shuts and zone 1 stays open and allow air to heat/ cool zone 1. If zone 2 thermostat simultaniously initiates the same heat/cool demand, the zone 2 valve opens and both zone heat/cool. When either thermostat is satisfied the opposite zone valve closes and when both thermostat are satisfied both zone valves open.
Hope this helps you understand zone operation. The same works for higher multizone systems.
If you look at the end of most dampers, there is a line on the end of the shaft. this line when it is in line with the duct it is open, and when it is 90 degrees to duct it is closed. for most damper and motor, when it rotates clockwise it goes to open. and counterclockwise it shuts. default position on zone systems is open, most damper motor spring return to open. There is a allen set screw that anchors the motor to the shaft. to set up the motor and shaft, turn power off, unset set screw and rotate damper ccw and reanchor the set screw, repeat for all damper and associated motors.
You need to have someone evaluate the ductwork for the home. With all zones calling, there should be an even balance of airflow. And when only one zone is calling, there should not be the tornado effect you describe.
The dampers feeding each zone may be of the wrong size. It also sounds as though you are also having a problem with your bypass damper. This damper is designed to bypass excess air when only one zone is calling. It is operated typically off the airflow alone.
Have it check out. You definitely have a problem. I would recommend getting it looked at by a company other than the installing company to remove any bias judgment or diagnosis.
Go down to where the ducts come out of the furnace. Identify the line you want to install damper. Open duct and drill two holes directly across from each other. Take your damper and undo the nut and washer on the one end and install in the holes you just drilled. Reattach the washer and nut and now re connect the duct seal it with duct tape and you will be good to go.
If you have 6 inch ducts get a 6 inch damper. But be sure to do everything at the beginning on the duct as to divert air to other ducts.
I have to tell you that changing your air flow could develop problems if you do very many ducts. So be very aware of what you doing. All systems are put in with air flow in mind.
Some of this depends on where the air handler/furnace is located. Most often in two story houses, it's in the attic upstairs, or in a closet upstairs. A duct routes air from the furnace to the downstairs supply duct, so it is a distance from the air handler. When the unit first initiates a heating cycle, that duct is going to be full of cool air, and the duct itself will be cool. So the furnace has to run long enough to push the cool air out, as well as warm the duct up, before your going to feel warm air at the registers downstairs.
Keep in mind, heat rises. And, your thermostat only monitors the immediate area where it's located. In your case, upstairs. Two story houses are problematic because of this. And one way around it is to have a damper system installed that distributes the air upstairs or downstairs based on a thermostat located in those spaces. There would be 2 dampers, and 2 thermostats (one upstairs, one downstairs). Each stat would control a damper, and the call for heat or cooling.
Let me know if you would like to consider a system like this, and I can point you to components to use. I've put several system like this in.
You will need a control to operate motorized zone dampers. In the ductwork, you will install a damper in each line going into the area you want zoned. If you have air conditioning you will also require a barometric relief damper that allows air to pass thru the ductwork and not restrict air over your A/C coil. Common controls are made by Honeywell and EWC.
If you already have the control module, you will run two or three (low voltage) wires from each motorized damper back to the control. Your thermostat wires (also low voltage) will run from each thermostat to the control module and connect to a zone relay. Match each zone by number. You will need to run power to the control module that will provide power to the thermostats as well as the motorized damper. Check on the reverse side of the control module and/or check on the web to find the wiring diagram.