Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.


Bimetallic vent dampers

Bimetallic vent dampers

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


RE: Bimetallic vent dampers

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.

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?

RE: Bimetallic vent dampers

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.

RE: Bimetallic vent dampers

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

Johnson Controls ( makes both.

Belimo is a major actuator company.

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.

RE: Bimetallic vent dampers

Where can I get a low ambient compensation kit?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


eBook: Product Innovation Platform Assessment
Over the past few years, there has been growing interest among industrial companies and solutions providers with regards to Product Innovation Platforms, where design, manufacturing and IoT tools are bundled into a single software package. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close