Hi

I am modelling a displacement ventilation system having a high space volume of around 22m high Ceiling.

Since we are collecting the return air only at 4m from finish floor, rest is hot unventilated zone, so we assume to consider an imaginary ceiling at 4m height. Thus, when I am modelling it with plenum, all the loads are ok except there is some amount of ceiling conduction gain from plenum to the space. But when I am modelling it without plenum, the wall cond for the peak summer is having a negative value.

Could anyone kindly help me to find out why this happen in trane trace and how to fix it.

Waiting for your replies.

Thank You