I am simulation a proposed residential building for LEED which is composed of a PTAC for cooling and a radiant floor for heating.
Because the building have a heated floor system I have switch off the heating coil of the PTAC.
The problem is that the fans are sized according the heating load which is the main load of the building, but this load its been already taken by the heated floor.
I have use hard values for the PTAC set up reducing the "supply air flow rates during heating operation" down to the "outdoor air flow supply during heating operation" but it gives me the following warning. Does anybody knows how to solve it?
** Warning ** Coil:Cooling:DX:SingleSpeed "P4:DWELLING02 PTAC DX COOLING COIL" - Full load outlet air dry-bulb temperature < 2C. This indicates the possibility of coil frost/freeze. Outlet temperature = 1.88 C.
** ~~~ ** ...Occurrence info = SANTIAGO, 04/07 22:50 - 22:53
** ~~~ ** ... Possible reasons for low outlet air dry-bulb temperatures are: This DX coil
** ~~~ ** 1) may have a low inlet air dry-bulb temperature. Inlet air temperature = 13.497 C.
** ~~~ ** 2) may have a low air flow rate per watt of cooling capacity. Check inputs.
** ~~~ ** 3) is used as part of a HX assisted cooling coil which uses a high sensible effectiveness. Check inputs.
Many Thanks,