York Millenium

[heelfan]

I have a customer with a York millenium vav rooftop unit. It is around two years old. The unit has Johnson unt controllers (factory installed) and the building has vav boxes with lon controllers on them. I want to reset the supply air based on worst zone, is there a way to get the signal from the lon boxes to the N2 controller. There was a lon card originally shipped with this unit but York has said it will not work.The unt uses a single space temp for reset but if I can use the worst zone I think I can achieve some significant energy savings. I was thinking of putting in a programmable controller and bringing all the space temps into it and writing some logic to find the greatest deviation from setpoint and reset supply air based on that and using a 0 to 10 out to the unt, I am not sure if the unt will accept it or not (these are labelled as Synthesis controllers by York but are a unt with an expansion board.
Any other suggestions would be great.

[amigo]

Originally posted by heelfan
the building has vav boxes with lon controllers

Which manufacturer's controllers are these?

I think you are on the right track.

Instead of writing too much code you could just average "terminal load %" (nvo from most LON vav controllers) and use that value for reset.
Terminal load automatically indicates how far from setpoint a controller is.

I am not too sure if looking at worst zone is always the best method of reset.

And like you say to bridge your LON system with N2, the most cost effective method in your case would probably be some type of hardwire connection.