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pesy (Mechanical) (OP)
15 Jun 05 19:47
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 (Mechanical)
16 Jun 05 11:57
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 (Mechanical) (OP)
16 Jun 05 13:04
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 (Mechanical)
16 Jun 05 13:37
If you have power, I recommend getting a line voltage thermostat to send an proportional analogue signal to a modulating damper actuator.

Johnson Controls (www.jci.com) makes both.

Belimo is a major actuator company. 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 (Mechanical) (OP)
13 Jul 05 21:19
Where can I get a low ambient compensation kit?

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