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Ask Rick Mather Your Own Question
Rick Mather
Rick Mather, HVAC Technician
Category: HVAC
Satisfied Customers: 3634
Experience:  35 years experience, HVAC
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I have a Bryant Preferred Series Fan Coil model FV4B. I would

Customer Question

I have a Bryant Preferred Series Fan Coil model FV4B. I would like to control the fan speed from a Johnson Control Metasys building automation system rather than a standard thermostat. I'm told this Fan Coil has a GE ECM 2.3 series motor. Can I interface to the fan coil's control board, or bypass the control board and control the motor directly?
Submitted: 8 years ago.
Category: HVAC
Expert:  Rick Mather replied 8 years ago.
Here is the web site for that fan coil but the documents section is down so I sent it so you would be able to try also. But I don't see why you coundn't take control of the fan with the right hardware
Customer: replied 8 years ago.
You havent really answered my question. I already had the documention which you reference (didnt need to get it off the web site as it came with the unit). It is not apparent to me how I can take control of the fan. I'd be happy to email the document to you for your review.
Expert:  Rick Mather replied 8 years ago.
I would almost say that the Byrant control board won't accept a 4-20ma or 0-10vdc to control the fan speed. Which is what Johnson Controls is goint to send out. I don't think you will find any documentation that will explain what you want to do with those fan coils. I will opt out so another expert might know
Expert:  Rick Mather replied 8 years ago.
Good luck I sent to another expert
Expert:  Mark Henley replied 8 years ago.



To do that what you need to know is what type of signal it needs to see at the board's input. If your Metasys has a 4 to 20 output with scaling which I believe it does, then it can be converted to any signal that the board wants to see including a resistive value with the addition of another component.


So the short answer is yes you can do it but you need to do a little more research to actually implement it. You can probably get the information you need from carrier as far as what type of signal you will need. My hunch is that its probably just a resistive value as that's the cheapest way to make the board.





Customer: replied 8 years ago.

Let me be more specific with my question.


The Bryant FV4B has an ECM motor controlled by "Easy Select" taps on a Printed Circuit Board. These taps are supposed to be used by the installer to configure the system. The ECM motor then uses the selected taps to modify its operation to a preprogrammed table of airflows.


Which taps (if any) can I control (from the Metasys) to force the ECM to a slower speed when only one zone of a 2-3 zone system is calling for air? I want to avoid using a bypass damper if I can.


Expert:  Rick Mather replied 8 years ago.
Mark will help from here on please accept his answer