weighted damper on return duct?a

[aw]

What is the purpose of a weighted damper on a section of duct coming from the supply plenum back to the return air side?

[corny]

Is the system zoned ?

If it is zoned then it is a relief damper to recirculate supply air back thru the machine during times when a smaller zone is calling.....


If its not a zoned system then I have no freaking idea.

[aw]

yes, it is zoned. Is it safe to assume when the system is off, the weighted portion should close off this duct?

[geodude]

What is the purpose of a weighted damper on a section of duct coming from the supply plenum back to the return air side?

To relieve excess pressure if a small zone is calling, also Its a band-aid for a poorly designed zone system. It is a call back waiting to happen, and leads to premature equipment failure. :p

[geodude]

yes, it is zoned. Is it safe to assume when the system is off, the weighted portion should close off this duct?

Yes

[mark beiser]

It should also be fully closed when the system is running with all zones calling.

[aw]

is there any harm with it being open all the time. Mine seems to be installed backwards.

[Tech Rob]

It's called a Static Pressure Regulating Damper. The damper will not open until the static pressure within the supply line increases to the point where it can overcome the weight of the damper. There is a movable weight on the damper shaft and the static pressure setpoint is changed by moving the weight either closer or farther away from the shaft.

The damper should be set to open completely at the static pressure created by the supply fan with only the smallest zone calling for air.

I would much rather see the air from these dampers discharged directly outside as opposed to into the return. They can cause systems to run extremely cold coils and flood liquid refrigerant back to compressors in the right [read: wrong] circumstance.

Unless you have a way to control the capacity of the compressor, airflow shouldn't really be messed with.

[mark beiser]

I would much rather see the air from these dampers discharged directly outside as opposed to into the return. They can cause systems to run extremely cold coils and flood liquid refrigerant back to compressors in the right [read: wrong] circumstance.

I hope you mean to another part of the house, and not actually to outside!
Something like that would cause several other issues that are worse than potentially shortened compressor life, lol.

[Tech Rob]

is there any harm with it being open all the time. Mine seems to be installed backwards.

Are you sure it's installed backwards? There should be an arrow on the damper pointing towards the return. I'd imagine it's more likely that the weight isn't positioned correctly on the damper shaft.

[aw]

pretty sure it is backwards. The weighted arm is in line with the duct whether the system is operatering or not. The only way to move the arm is 90 degrees to the right or towards the roof.

[Tech Rob]

I hope you mean to another part of the house, and not actually to outside!
Something like that would cause several other issues that are worse than potentially shortened compressor life, lol.

Well, dumping it in another part of the house wouldn't be good either... Especially if the sensor is satisfied.

But.... I just re-thought my whole half-baked theory about discharging supply air directly outside of the conditioned space.... Overloading the evap and space pressurization hadn't occurred to me. :o:confused::rolleyes:

Yeah.... So... I'm going to stop trying to reinvent the wheel here.

Thanks, Mark :D

[karsthuntr]

pretty sure it is backwards. The weighted arm is in line with the duct whether the system is operatering or not. The only way to move the arm is 90 degrees to the right or towards the roof.
A picture is worth a 1000 words.

[aw]

does not matter if system is on or off...position of weight is the same

[geodude]

:pbad design.

[mark beiser]

The damper is closed, and installed with the airflow in the correct direction.

Do you have a lot of air noise when just one zone is calling?

[captube]

There are 2 counter weights shown in the photo, what is the brand name of zone module?
I have only seen 1 counter weight with by-pass, 2 could hold it in the closed position i assume.