[Equest-users] App G model VAV w unmet loads in heating

[Daniel Knapp]

Hi Matthew,

I have run into this problem myself for buildings in cold climates.  The problem is that the reheat coils are sized to the reheat delta T (defaulting to 30ºF) which usually assumes a supply air temperature of 55ºF maybe resetting to 65ºF in heating mode.  However, in winter, the supply air temperature can dip quite a bit lower than this (down to 30ºF or lower) unless you have a central heating coil.  The DOE keyword is HEAT-SET-T and it's worth checking the .inp file to make sure this keyword is set.  In eQuest you need to set the “Hot Deck Max Leaving Temperature” (maybe to 65ºF) to activate HEAT-SET-T.  You might also try setting COOL-CONTROL = WARMEST to reset the supply air temperature upward as loads permit and increase the “Reheat Delta T” to 40ºF. 

If this doesn't work, send your .pd2 and .inp up the list and maybe someone can have a quick look at the file.

All the best,
Dan 

—
Daniel Knapp, PhD, P Phys, LEED® AP O+M
danielk at arborus.ca

Arborus Consulting
Energy Strategies for the Built Environment
www.arborus.ca
76 Chamberlain Avenue 
Ottawa, ON, K1S 1V9 
Phone: (613) 234-7178 ext. 113
Fax: (613) 234-0740




On 2013-07-30, at 9:03 AM, Matthew Baron <mbaron at wendelcompanies.com> wrote:

> HI,
> I am working on several school models and they generally fall into the packaged vav with reheat category. The spaces are fine for cooling, but are way off for heating. When I look at the ss-p report the heating capacity for the units shown to be zero, when I look at the ss-a report it indicates the heating load. I have entered the hot deck temp, zone entering temp, a preheat coil. Any suggestions would be appreciated.
>  
> Thanks,
> Matthew J. Baron
> <image002.png>
> 
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