Two HVAC system definition problems

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eQuesters and DOE2-2ers,

I have two problems concerning the code below, from my .inp file as
processed by eQuest into a BDL file:

1. Per my e-mail yesterday, I am trying to figure out how to make line
3275 do hot-gas reheat. Any ideas? Apparently, the only gas that DOE2-2
recognizes is combustible natural gas - not what I intend here.

2. What is the problem with line 3278? According to text page 361 (PDF
page 368) of the DOE22Vol2-Dictionary.pdf, this line is permissible and
meaningful. What I am trying to do is simply tell eQuest that HVAC has a
constant 216 CFM of OA. Since DOE2-2 won't allow such a simple thing, I'm
trying to define it instead as 10.29% of the 2100 CFM that this PSZ delivers
to the single zone that it serves. Any ideas?

I'm tired of reverse-engineering the whole world just to tell eQuest
simple little things. However, if I do things in eQuest proper instead of
in the .inp file, then I have no idea what variables trump other variables,
or even how to conjure all of the mysterious data that eQuest shows/asks
for.

Thanks, everyone, for accepting my daily quiz.

Lars Fetzek, EI

*3272 * "HVAC3 System" = SYSTEM
*3273 * TYPE = PSZ
*3274 * HEAT-SOURCE = ELECTRIC $verify
*3275 * ZONE-HEAT-SOURCE = NONE $How do I make
this hot-gas reheat?
*3276 * BASEBOARD-SOURCE = NONE
*3277 * MIN-SUPPLY-T = 51.36
*3278 * MIN-OA-METHOD = FRACTION-OF-DESIGN
*ERROR**************************** ==================
****************************************ILLEGAL CODEWORD
*3279 * FAN-SCHEDULE = "HVAC3 Fan Sch"
*3280 * FAN-PLACEMENT = DRAW-THROUGH
*3281 * FAN-CONTROL = CYCLING
*3282 * SUPPLY-KW/FLOW = .000749
*3283 * SUPPLY-DELTA-T = 0 $Net capacity value used
*3284 * COOLING-CAPACITY = 88170
*3285 * COOLING-EIR = .316
*3286 * CRANKCASE-HEAT = 0
*3287 * CONTROL-ZONE = "Zone Space 3B"
*3288 * ..

Lars Fetzek's picture
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Lars,

For 1) , I assume you?re trying to recover heat from the hot gas side of a DX cooling coil. This is considered waste heat, so I would research WASTE-HEAT-USE = SPACE-HEAT. The screen shot below shows where to get started, and you?ll need to determine what percent of your condenser capacity is available for reheat. Note that it only works for packaged multizone systems, so you probably need to treat your single zone system as a multizone with only one zone.

For 2), you accomplish it two ways. At the system level, you could define the following:

MIN-OUTSIDE-AIR = 0.1029

OA-CONTROL = FIXED

You?re using MIN-OA-METHOD, but that?s more for specifying whether you?re using an economizer or demand-controlled ventilation. You?ll want to use OA-CONTROL to specify that the defined percent is constant (rather than a minimum). In the interface, this is selected under economizer control (FIXED meaning there is no economizer).

The other way to specify an exact flow is at the zone level:

OUTSIDE-AIR-FLOW = 216

If you specify it at the zone level, you could leave the MIN-OUTSIDE-AIR undefined at the system level. Zone OA settings/requirements trump whatever is specified at the system level. When zone & system settings are in conflict, it often results in a warning in the SIM file.

Thanks,

DAKOTA KELLEY

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