[Equest-users] disabling zone electric heat?

[Nick Caton]

Hey James,

 

The airflow part is pretty simple I think, but I'm not sure whether
there is a clean way to make an "heating availability schedule" that
would apply only to the zone reheat...  

 

I'd like to think there should be a clean/direct way to pull that off,
but nothing comes to mind... indirectly it might be do-able through a
combination of zone-level thermostat sch tweaks and system level heating
availability schedule & delivery temperature tweaks, but I'm not totally
sure...  Hopefully someone else has this fresh in their head to share?

 

In any case, to define morning warmup airflow as you're describing (100%
open VAV terminals), look to the highlighted field at the zone level:

 

 

 

Here's the associated help entry:

MIN-FLOW-SCH

Takes the U-name of a schedule of TYPE = FRAC/DESIGN whose values are
values of minimum flow ratio. This schedule will override the specified
or calculated value of MIN-FLOW-RATIO unless the schedule value is -999.
In this case the specified or calculated value of MIN-FLOW-RATIO, which
is found on report SV-A for each zone, is used for that hour. This
schedule can be used with a value of 1.0 during warmup periods and -999
for other hours to simulate VAV boxes that are fully open during warmup.

~Nick

 

 

 

NICK CATON, E.I.T.

PROJECT ENGINEER

Smith & Boucher Engineers

25501 west valley parkway

olathe ks 66061

direct 913 344.0036

fax 913 345.0617

www.smithboucher.com 

 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of James
Hansen
Sent: Tuesday, March 15, 2011 1:29 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] disabling zone electric heat?

 

I've got a project where we have shutoff VAV boxes with electric heat
and RTUs that provide the supply air and have HW heat (mainly for
preheat of OA).  The RTUs are also used to provide morning warmup heat.
During the 60 mins or so that morning warmup is occurring, the RTUs send
out 80 degree air, and the electric heat at the shutoff boxes is
disabled (they are forced open 100%).

 

Has anyone modeled this successfully?  If I could disable zone heat for
one hour a day (5:00am-6:00am), I would think the RTU would raise its
supply air temp to compensate.  But this is not possible as far as I
know.  Thanks for any tips!

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

www.ghtltd.com <http://www.ghtltd.com/> 

 

 

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