Re: [EnergyPlus_Support] how to fix the recurring errors

On Sat, Jun 30, 2012 at 4:50 PM, CleanTech Analytics <jeremiah@xxxxxxxxxxxxxxxxxxxxxx> wrote:

Below I have pasted the info for an EMS script provided to me by Jim Dirkes from the Building Performance group- it should work to fix your issue.

Your DX coil is trying to operate in cool weather. When it does, it applies its full capacity to the airstream and cools it down to freezing temperature.

This is the same error that Joe Huang posted about the other day (I think).

You?ll need to :
1.       Ignore it (after confirming that it?s not indicating some other problem)

2.       Turn off the coil during cold weather (after looking at the weather file to see when weather is below about 55-60F)

3.       Run an EMS script to turn off the coil whenever outdoor temp is lower than a set value

p.s., Certain ?baseline? systems (e.g., a heat pump serving an interior zone) don?t handle the situation well where an economizer is not used such as is the case in a warm climate zone. They need cooling in the cold weather, but the DX system doesn?t like operation then. (This is not a likely ?real? system, since engineers know these things. But a ?baseline? is not real?)

Here?s an EMS routine (grateful credit for which goes to Jim Dirks + Jean Marais + the Help desk a few months back):

DX coils that you want OFF via this routine must have their Unitary object specified with the same schedule which the EMS routine is turning on and off (?SchCpct_LowTempOFF? in this example)

Jeremiah D. Crossett
CleanTech Analytics
503-688-8951
www.cleantechanalytics.com

This document may contain valuable information proprietary to CleanTech Analytics which is private and confidential. It may not be shared, copied, stored or transmitted in any form without the prior written consent of CleanTech Analytics

On Sat, Jun 30, 2012 at 1:43 PM, Jia Hu <hujia06@xxxxxxxxx> wrote:

Thanks, is there any way to disable E+ to show these warnings. These warning seems to cause BCVTB error "Error: Unspecified error when reading from socket." because of E+ takes longer time to generate outputs.

Thanks,

On Sat, Jun 30, 2012 at 4:36 PM, CleanTech Analytics <jeremiah@xxxxxxxxxxxxxxxxxxxxxx> wrote:

This is an indication that your cooling may be turning on during times when it is cold outside. Your building may be internal load dominate so this cooling could be necessary.

If you search the list there have been several recommendations for a fix to this including using an EMS script..
However the warnings that are not severe can be ignored, I suggest you do not worry about the possibility for coil freeze and continue with your model with the warning..

Jeremiah D. Crossett

CleanTech Analytics
503-688-8951

www.cleantechanalytics.com

This document may contain valuable information proprietary to CleanTech Analytics which is private and confidential. It may not be shared, copied, stored or transmitted in any form without the prior written consent of CleanTech Analytics

On Sat, Jun 30, 2012 at 1:27 PM, Jia Hu <hujia06@xxxxxxxxx> wrote:

Hi,

I use example file generator and use package unit HVAC system provided by the example file generator. I got many following recurring error, how can I fix this? If necessary I can provide the IDF file. Thank you!

** Warning ** Coil:Cooling:DX:SingleSpeed "PSZ-AC_1:12:12_COOLC 1 DXCOIL" - Full load outlet air dry-bulb temperature < 2C. This indicates the possibility of coil frost/freeze. Outlet temperature = 1.94 C.

** ~~~ ** ...Occurrence info = LONDON/GATWICK - GBR IWEC Data WMO#=037760, 01/15 01:38 - 01:39
** ~~~ ** ... 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 = 15.542 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.

** Warning ** Coil:Cooling:DX:SingleSpeed "PSZ-AC_1:6:6_COOLC 1 DXCOIL" - Full load outlet air dry-bulb temperature < 2C. This indicates the possibility of coil frost/freeze. Outlet temperature = 1.94 C.

** ~~~ ** ...Occurrence info = LONDON/GATWICK - GBR IWEC Data WMO#=037760, 01/15 01:45 - 01:46
** ~~~ ** ... 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 = 15.542 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.

** Warning ** Coil:Cooling:DX:SingleSpeed "PSZ-AC_1:3:3_COOLC 1 DXCOIL" - Full load outlet air dry-bulb temperature < 2C. This indicates the possibility of coil frost/freeze. Outlet temperature = 1.66 C.

** ~~~ ** ...Occurrence info = LONDON/GATWICK - GBR IWEC Data WMO#=037760, 01/15 03:18 - 03:19
** ~~~ ** ... 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 = 15.556 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.