Re: [EnergyPlus_Support] DX Cooling Coil warning

Vinay

On Thu, Jul 8, 2010 at 9:25 PM, James V Dirkes II, PE <jvd2pe@xxxxxxx> wrote:

Dear Vinay,

Standard 90.1 says you must model a heating and cooling system, but does not say that it must be operating continuously. Obviously, most cooling systems are OFF during cold weather; this is normal and expected. I suspect that cooling IS available via an economizer control.

If, for some reason, you actually need to operate your DX system in the middle of the winter as sometimes is the case, I?m not sure what to do. I think, though, that you can adjust the coil curves to reflect the actual equipment?s operation without causing a problem in E+.

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Vinay Devanathan
Sent: Thursday, July 08, 2010 8:54 PM

To: EnergyPlus_Support@xxxxxxxxxxxxxxx

Subject: Re: [EnergyPlus_Support] DX Cooling Coil warning

Mr. Dirkes,

Thanks for your reply.

But, I have a question. According to Appendix G, should the system not be capable of providing heating and cooling throughout the year?

Regards,
Vinay

On Thu, Jul 8, 2010 at 8:45 PM, James V Dirkes II, PE <jvd2pe@xxxxxxx> wrote:

Dear Vinay,

·         A simple way to fix this is to assign an availability schedule to the cooling coil which is ON only during warmer months. For the coil below, I?ve used an ?AlwaysOn? schedule, but you can create any schedule that you like, perhaps similar to the one I show at the bottom.

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Vinay Devanathan
Sent: Thursday, July 08, 2010 8:24 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] DX Cooling Coil warning

Hello All,

How do I control a Dx:CoolingCoil from operating when the inlet air temperature required no cooling. In my case,

Full load outlet air dry-bulb temperature < 2C. This indicates the possibility of coil frost/freeze. Outlet temperature = 1.90 C.
   **   ~~~   ** ...Occurrence info = RUN PERIOD, 01/16 11:24 - 11:26
   **   ~~~   ** ... 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 = 16.946 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.

this is what happens..

I have a Setpoint Manager (Mixed Air) for the cooling coil outlet node. The reference setpoint for this is through Setpoint manager:Singlezone:Reheat.

Could anyone please tell me what is wrong with this?

Thank you very much.

Regards,
Vinay