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Kevin VanderWarf
04-05-2007, 12:29 PM
In all my years in HVAC, I never dealt with these pneumatic(?) damper controls. Either way, what ever you call it, there is this hose that's just stuck into the duct very loose.
Should there be some sort of fitting inserted into the duct to attach these to.
Jerry Peck
04-06-2007, 09:56 AM
Are you sure that is not an electrical wire to an electrically controlled damper?
Tim Moreira
04-06-2007, 10:39 AM
Kevin,

I don't know what that is, but in all my years in hospitals with pneumatically controlled dampers, I have only seen where the damper inside the duct is connected to an arm that extends to the outside of the duct and is connected to a pneumatic actuator. The pneumatic line (which is only about 20 psi or so) is connected to the actuator.

The damper is controlled most likely through a computer operated system that connects to an E/P control box. The E/P box is an 'electrical/pneumatic' control box that regulates the damper. It is also interlocked into the fire alarm via a relay. If the alarm goes off, the interlock kills the pneumatics and the damper closes automatically. All of the dampers I have seen are normally closed for this reason.

My only other thought on that line stuck in there is if it is part of a magnahealic (sp) that reads the differential pressure across the filters at the AHU. This way they know when to change the filter based on the difference in pressure on the magnahealic (sp) gages.
Tim Moreira
04-06-2007, 10:26 PM
Kevin,



Should there be some sort of fitting inserted into the duct to attach these to.


Yes, normally a pneumatic line is not just drilled and stuffed like that. There should be a correct fitting (double sided barb) that is attached to the duct work. The line should attach to a "barb" on the outside and then another line should attach to the "barb" on the in side before terminating at the actuator.

I have never seen an actuator inside the duct. But then again...:)
Kevin VanderWarf
04-07-2007, 02:05 AM
Magnahealic, pneumatical, interlockin thing-a-ma-gigger.
Yep, thats what I thought it was.LOL (over my head).

I did go ahead and write up that the loose hoses need proper fittings at the duct penatrations.
Thanks for your help Tim.