[Equest-users] Throttling Range and Pipe Insulation

[Daniel Bersohn]

Walt,

 

1)       This means that you have a zone that's not getting heating or
cooling when it wants it.  34.1% probably means there's an issue with
your system topology or your system really has unmet load hours in real
life.  If you have one thermostat and lots of rooms with different
internal loads and exposures you're guaranteed to get a lot of unmet
load hours.  The plant having zero unmet load hours means the plant is
satisfying all the requests its getting from equipment that serves
zones.  So the zones aren't getting what they want from AHUs, radiators,
etc. but the plant is doing everything AHUs, radiators etc. want it to.

2)       Any piping downstream of a steam control valve in a two-pipe
system in the same space served by the radiator doesn't need insulation
because it's acting as a radiator.  In a one-pipe system,0 if you have
TRVs on the air vents, any pipe that only serves one radiator and is in
the same space as that radiator need not be insulated since it serves as
a radiator.  If you don't have TRVs on your air vents in a one pipe
system (or in place of the control valves on two-pipe for that matter)
the insulation probably doesn't matter that much since all the radiators
deliver heat (and too much of it at that) at the same time as all the
uninsulated pipe.  For the remaining pipe you'd estimate the surface
area of the piping to be insulated and multiply the U factor of the
insulation by the surface area of the pipe.  Put that into the hot water
loop you're using as an analog for your steam system in detailed mode.


 

Daniel Bersohn, LEED AP
Mechanical Engineer
Buro Happold Consulting Engineers PC
100 Broadway
New York, NY 10005 USA

+1 212 334 2025 Office
+1 212 616 0391 Desk

daniel.bersohn at burohappold.com
www.burohappold.com <http://www.burohappold.com/> 



________________________________

From: Walt Henry [mailto:WHenry at thielsch.com] 
Sent: Thursday, January 21, 2010 8:55 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Throttling Range and Pipe Insulation

 

Good morning eQUEST users,

 

I have two requests:

 

1)       What is the definition of "throttling range"?  I have always
had 0 until my last project which is a Police Station.  We do mostly
energy retrofits and the existing boiler, 37 years old, has an input of
450 MBH.  The total HVAC load is 222.651 MBH per eQUEST.  For the first
time Report BEPU shows my base case model to be 34.1% outside of the
throttling range.  What does this mean?  The % of hours any plant load
is not satisfied is 0.

 

2)       I have a church to model, starting this morning, which has no
insulation on the steam piping and we want to determine the savings by
putting 1" of              fiberglass on the pipes.  Usually we would
determine the savings in e-plus but is there any way to model this in
eQUEST?  There are other measures and it would be convenient to have
everything in one report.

 

Walt Henry

Energy Specialist

RISE Engineering

1341 Elmwood Ave.

Cranston, RI 02910

U.S.A.

Phone:  401-784-3700 Ext. 119

Fax:      401-784-3710    



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