[Equest-users] Spam:Re: Heating problems....

Jay Keazer JKeazer at tmecorp.com
Tue May 27 06:07:01 PDT 2008



I would check the value of "Reheat Delta T" under Heating > Coil Cap/Control
on your system.  This value sets a limit on the change in supply air
temperature as it passes through the terminal unit reheat coils.  The default
of 30 F often causes this warning for me.  For example if your air handler
discharge temperature is 55 F and your desired zone supply temperature is 100
F,  your "Reheat Delta T" would need to be 45 to allow this to happen in the
simulation.  The default of 30 would only allow 85 F zone supply air



Jay Keazer, EI

Energy Services Division



2039 Green Acres Rd.

Fayetteville, AR  72703

Phone: (479) 521-8634

Fax:       (479) 521-1014



From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Jeff
Sent: Thursday, May 08, 2008 1:12 PM
To: Sheila
Cc: equest-users at lists.onebuilding.org
Subject: Spam:Re: [Equest-users] Heating problems....


Thank you for responding. When I do a simulation it aborts the run, then I
cant see the SS-F / SS-R reports.

	----- Original Message ----- 

	From: Sheila <mailto:sheila at energyopportunities.com>  

	To: Jeff Schorsch <mailto:jschorsch at hmg-associates.com>  

	Sent: Thursday, May 08, 2008 12:28 PM

	Subject: RE: [Equest-users] Heating problems....


	Hi Jeff,


	How many hours of unmet load do you have for zones served by these
units?  See reports SS-F and/or SS-R.  I often have these warnings even when
all my zones are conditioning properly.  If that is the case, ignore the
warnings and don't waste your time trying to fix them.  The nice thing about
SS-F is that it will tell you how cold the zones are getting and the months
unmet load hours occur.


	If you have a lot of unmet load hours, I would start checking to see
if my zone thermostat schedules, heating availability schedule, and fan
schedules match.  If the hours of unmet load occur during the summer, you
have simultaneous heating and cooling.  Try setting the heating thermostat to
55 during the summer months to eliminate the call for heating.


	Good luck.


	Sheila Sagerer

	Energy Engineer, EIT, LEED AP

	Energy Opportunities, Inc, a 7group company

	Phone: 717-880-9069





	From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Jeff
	Sent: Thursday, May 08, 2008 12:40 PM
	To: equest-users at lists.onebuilding.org
	Subject: [Equest-users] Heating problems....

	This is still my first time creating my simulation and I thought I
was on the right track...

	I have a 100% OA unit with a preheat coil and chilled water cooling
coils to maintain a 52 deg off the coil. The zones are 

	handled by singe duct, straight VAV terminal units with hot water
reheat coils. I have set all

	the zone set points to 72 degrees and I am getting a message that
reads as shown below. I have 

	inputted the heating capacity for the preheat coil and the capacity
for heating in the zonal VAV terminal unit.

	Just to see what would happen I grossly oversized the VAV heating
capacity to see if the error would be fixed,

	it did not. I checked the LS-B space peak loads and it shows that the
zone heating capacity required is only 25% of what I am inputting. Please
help, I have no clue what I am doing wrong.


	ZONE TU1-6 

	might have insufficient heating capability.

	Check that the SYSTEM or ZONE HEATING-CAPACITY plus this

	ZONEs BASEBOARD-RATING is adequate to maintain the ZONE

	specified DESIGN-HEAT-T for the calculated peak ZONE load

	(see LS-A or LS-B for the ZONE peak load.)


	which supplies the above listed ZONE, has a design heating

	coil exit temperature, HEAT-SET-T,(plus any zone reheat)

	below its MAX-SUPPLY-T or the ZONE DESIGN-HEAT-T, which

	might account for the insufficient heating capability.



	70 N.E. LOOP 410 SUITE 1070


	jschorsch at hmg-associates.com



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