modifying a constant volume reheat system

[BronYrAur]

I have been asked to look into the HVAC for a board room that will be constructed in part of a library. Right now the entire area is served by a constant volume multizone unit with 4 zones. There are reheat coil through the space, however, so I essentially have many zones.

Obviosuly I would never make a new system constant volume with reheat, but that is what I have to start with. Rather than try to change the entire system, I was thinking of just making sure I have enough cooling air and reheat coil to handle my board room load. Use will be intermittant and loads will be only computers and other equipment and people (no envelop load). Ventilation is brought in through the multizone unit. Any problem with that from an engineering perspective?

Now how about code wise. Job is in Northern IL USA. Is there a grandfather clause that will allow me to have constant volume with reheat, because I am pretty sure that it is not allowed ... at least by ASHRAE? Of course, ASHRAE is not a governing body either.

 

[imok2]

You may want to blank off the hot deck and add low pressure VAV dump boxes with new reheat coils in the branch duct after the VAV boxes. This system works well in conjunction with an economizer cycle to minimize reheat energy.

 

[lilliput1]

If your zoning is such that all rooms served by a particular unit would all be on heating or all on cooling, you may consider the Thermafuser Diffuser type which used constant volume of air but supplies variable volume to the conditioned space and the balance to the ceiling return air plenum space. You would need to make sure cable wiring are plenum rated to allow conversion of above ceiling space as a return air plenum