Bimetallic vent dampers

[pesy]

I'm looking for a company that manufactures bimetallic vent dampers that can make a custom one.

I have a 6" duct system in which I want to compensate (passively) for inlet air temperature. A bimetallic damper that has a range of:
120F full open
-40F partially closed to allow the same mass flow of air as there was in the fully-open 120F situation.

would do the job.

Perhaps there is something else that would do the same job

Pesy

 

[ChrisConley]

The closest thing I have ever heard of to what you want is a thermally actuated diffuser.

A wax is used to actuate the diffuser.

http://www.eng-tips.com/viewthread.cfm?qid=86178

The above is a discussion on thermafusers.

Having said all that, I'm pretty sure that the diffusers aren't designed for the temperatures you have listed. I'm assuming that there is no electricity available? Perhaps a solar collector and battery could be arranged to power the damper?

 

[pesy]

Power is available--however a control system to determine how much power to deliver to the device is not available. A self-controlling device would be fine.

 

[ChrisConley]

If you have power, I recommend getting a line voltage thermostat to send an proportional analogue signal to a modulating damper actuator.

Johnson Controls (

http://www.jci.com)

makes both.

Belimo is a major actuator company.

http://www.belimo.com

Another standard solution is to use a 'low-ambiant compensaition' kit. Which consists of an outdoor air sensor and a three position damper. When outdoor air drops below a certain point the damper closes slightly to reduce the mass flow.

It depends on how precisely you want to control mass flow.

 

[pesy]

Where can I get a low ambient compensation kit?