[Equest-users] Excessive Unmet Heating Load Hours with an Auto-Sized HVAC System

[Peter Hillermann]

Pasha,

 

Can I use a baseboard as radiant tube heat from the ceiling (gas hookup with
Flue)? My thought is it's a computer how does it know whether the heat is
coming from the ceiling or the floor as long as its heating the perimeter.
Would I be correct or should I just go sit in the corner now and be quiet?

 

PS: I'm too lazy to draw perimeter zones just for a radiant heater and its
Friday. (Just joking)

 

Thanks,

 

PETER HILLERMANN

 

peterh at westallarchitects.com

 

westall

architects

3404 pierce drive

chamblee, georgia 30341

 

o 770.458.4113

f  770.458.5352

c 678.898.2936

 

westallarchitects.com

e-signatureUSGBC-Logo

 

 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Pasha
Korber-Gonzalez
Sent: Thursday, June 10, 2010 10:55 PM
To: Robert Des Rosiers
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Excessive Unmet Heating Load Hours with an
Auto-Sized HVAC System

 

I have found with my own projects that even sometimes when the HVAC designer
has specified a specific capacity for htg water equipment that sometime in
my model file I still have unmet loads for htg.  I suggest at this point
specify additional htg capacity by either increasing the reheat delta-T from
say 30F to 50F and/or adding zone level baseboards.  By adding the
baseboards you are adding a component of the system that will supplement the
skin losses being experienced by the simulation model.

 

by adding baseboards for the additional requrired heat then you should be
able to meet your heating loads.

 

hope this helps,

pasha

On Thu, Jun 10, 2010 at 7:38 PM, Robert Des Rosiers
<desrosiers at studioma.com> wrote:

All:

I have completed an energy model for a baseline scenario from which to
compare my proposed design.  The baseline HVAC system is a constant volume
single zone AHU w/ no reheat; the AHU is served by HW and CHW loop from a
central plant.  I have set this up in eQuest as a "Variable Air Volume"
system type with the AHU fan control set to "Constant Volume"; my thought
here is that each zone fed by the AHU will control temperature using a VAV
box w/ no local reheat or cooling.  Flow and temperature from the AHU will
be delivered based on the coolest or warmest zone it serves.

 

All seems fine with the design flows, ventilation flows and cooling
capacities.  My problem is with the heating capacity as I have excessive
unmet heating hours (50,000).  I have allowed eQuest to size the heating
capacity of the preheat and heating coil as well as the minimum flow ratios.
Does anyone have any thoughts as to what is causing these unmet heating load
hours?  Is the way I have set-up the desired baseline HVAC system incorrect?

 

Any guidance is greatly appreciated.  Thanks -

 

Robert Des Rosiers, LEED-AP

STUDIO MA

130 N Central Avenue, No.300 Phoenix, Arizona 85004

Telephone 602 251 3800

Fax 602 251 3100

 


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