Thank you for your reply.
In real life its an only heating system. I had to include a PTAC due to the appendix G requirements that said when there is no cooling system I have to use the baseline´s system (PTAC).
I am wondering if is it possible to remove the heating coil so the sizing of the fan is according only with the cooling load?
Kind Regards,
El 24-09-2012, a las 19:36, Karen Walkerman <kwalkerman@xxxxxxxxx> escribió:
It looks like this warning is flagged because the outlet temperature is less than 2C - which in real life can indicate frost on your cooling coil. It means that your heating coil is not turning on (what you want).
I am curious - how is the system operated in real life? Is the outdoor air drawn in through the PTAC? Is there no preheat of outdoor air before it is delivered to the space? If outdoor temperatures get really cold, occupants will be unhappy when the ventilation system operates and blows cold air on them.If this is really how your system operates, I would say that you can ignore this error. Just make sure that your equipment is given the proper heating and cooling sequence in ZoneHVAC:EquipmentList--KarenOn Mon, Sep 24, 2012 at 3:03 PM, Felipe Duran <felipe@xxxxxxxxxx> wrote:
Dear Group,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,<PastedGraphic-1.tiff>