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Re: [EnergyPlus_Support] Re: Sizing according to ASHRAE 90.1
This also happens when the minimum damper position is set too high.
Yes on your interpretation of operation.
Sort of yes on your interpretation of supply air temp. You should report
the supply air temp and review the output (plot for quick answer). It
depends on the control of the supply air temp (i.e., scheduled vs
floating SP). Not sure which is required by App G.
On 8/29/2012 11:17 AM, Jean marais wrote:
> So mentally I can consider the delivery temps as James stated, but a type of virtual availabilitymanager that overrides the zone cooling setpoint temperature with that of the zone heating setpoint whilst the reheat coils are reheating...now I see what James meant by energy saving measure. Thanks for the clarification.
> In practice where the reheat coils are always available, this situation will occure when a hot day is followed by a cold night...the room temperature will float down from the cooling setpoint of 26 until it hits the lower limit of 20 deg C, when the reheaters will kick in but maintain a temp no higher than 20 deg C. The next day, if the zone warms above 20 deg C, the reheaters will at somepoint turn off and the zone will warm up and float toward 26 deg C. All this time the delivery air temp to the zone is CLG_SP-11 when in cooling mode and HTG_SP+11 when in heating mode.
> One of the other points I would like to ask is this:
> The SP+-11 deg rule applies to the "design" conditions the way I read it. To me this only occurs at times of peak loads, meaning the temps may modulate when not at design conditions. Would you aggree?
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>> No, it means that if the reheat coils are operating during the cooling
>> season, which they sometimes do, that the zone temp will be controlled
>> to the thermostat heating set point (20C). If the zones are over-cooled
>> and require that the reheat coils turn on, the air temperature in the
>> supply duct after the reheat coils will be whatever it needs to be to
>> bring the zone temp back up to to 20C.
>> Run a simulation and review the zone temp when the reheat coils are
>> active. The zone temp should be maintained at the zone thermostat
>> heating set point temperature. You can then look at the supply air temp
>> leaving the reheat coil and see what temperature that node is.
>> On 8/29/2012 10:08 AM, Jean marais wrote:
>>> Richard said: "E+ will control the reheat coils to the heating setpoint when the system is in cooling mode"
>>> This means that if my heating (winter) zone setpoint is 20 deg C, then the air delivered after reheat in cooling mode will be 20 deg C.
>> Richard A. Raustad
>> Senior Research Engineer
>> Florida Solar Energy Center
>> University of Central Florida
>> 1679 Clearlake Road
>> Cocoa, FL 32922-5703
>> Phone: (321) 638-1454
>> Fax: (321) 638-1439 or 1010
>> Visit our web site at: http://www.fsec.ucf.edu
>> UCF - From Promise to Prominence: Celebrating 40 Years
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Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL 32922-5703
Phone: (321) 638-1454
Fax: (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu
UCF - From Promise to Prominence: Celebrating 40 Years
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
The group web site is:
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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