[Bldg-sim] Baseboard heaters in VAV system

Brandon Nichols BrandonN at Hargis.biz
Thu Aug 21 16:13:28 PDT 2008


Here's a nifty user expression to size baseboards based on BTU's per
unit area -- in this example 30 BTUs per SF:
 
#LR("SPACE","AREA")*-30 
 
Plug this into the 'Baseboards / Capacity' field for each zone with
baseboards (rightclick to get the context menu, select 'Edit/View User
Expression', etc.)
 
Brando 

  _____  

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Robby
Oylear
Sent: Thursday, August 21, 2008 8:54 AM
To: 'Andrew Craig'; 'James Hansen'; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Baseboard heaters in VAV system



I was under the impression that eQUEST either doesn't size baseboards
correctly or at all.  The few times I've had to use baseboards I have
had to solve the underheated hours by manually sizing the baseboard
heaters at the zone level.  It's a pretty tedious process.

 

Robby Oylear

Mechanical Engineer

direct: 206.788.4571

cell: 206.354.2721

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

  _____  

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Andrew
Craig
Sent: Thursday, August 21, 2008 8:41 AM
To: James Hansen; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Baseboard heaters in VAV system

 

James---

 

In my opinion, baseboards act a little funny in eQUEST.  This is how
I've made the scenario you describe work:  

 

Under the Heating tab of your unit (Coil Cap/Control), restore the
default in the reheat entry so it is blank.  Make sure the Hot Water
Loop is still enabled as the zone heating source though.  Under the
Preheat/Baseboard tab, specify Baseboard Source as the Hot Water Loop.
You can change the default entries for the baseboards (pressure drop,
delta T, valve, etc.)  if applicable.  Then for each perimeter zone, go
into the heating tab and change the Baseboard control to Thermostatic if
it isn't already selected.  I've had trouble getting the Outdoor Reset
selection to work and most of our projects have baseboards controlled by
thermostats anyway.  You can also enter the capacity of the baseboards
for each zone or let the system self-size.  This should work...if not
I'd be happy to look at the inp.

 

Regards,

 

Andrew Craig, EIT,LEED AP/ Mechanical Designer 
INTERFACE ENGINEERING 
direct 503.382.2696 

  _____  

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James
Hansen
Sent: Thursday, August 21, 2008 8:18 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Baseboard heaters in VAV system

 

I've got a building that cools with shutoff VAV boxes and heats with
perimeter hydronic baseboard heaters.

 

When I'm setting up my system, do I specify hot water baseboard heaters
and leave the Zone Heat Source set to "Not Installed", or do I specify a
hot water loop for the Zone Heat Source, and eQuest knows to apply this
to the baseboard heaters and NOT the shutoff VAV boxes?

 

I currently have the Zone Heat Source as "Not Installed", but it appears
from my SS-R reports that there are hundreds of hours of underheating,
so something is not working correctly.  I've had my hot water loop set
to snap, demand, and scheduled, so I think the loop is running
correctly.

 

Thanks in advance!

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Direct)

703-243-1200 (Office)

703-276-1376 (Fax)

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

 

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