[Equest-users] Fw: insufficient heating capability

[Jeremy Poling]

By chance, does the building have a significant amount of glass at the
exterior in a climate where heating is required at some point during the
year?  I have seen this warning persist in energy models of buildings
where the envelope load is unsatisfied due to lack of baseboard heat.
This is a design issue, though, and should probably be brought up to the
system designer instead of tweaked in the model until it goes away.
Cost and aesthetics are often used as reasons to eliminate baseboard
heat, whereas the energy model and some basic ASHRAE 55 calcs may show
that to be a bad choice (or at least give the energy modeler and the
system designer a CYA when the occupants start complaining).

 

Just a thought...

 

Jeremy R. Poling, PE, LEED AP+BDC



 

From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Brad
Robinson
Sent: Monday, July 25, 2011 6:48 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Fw: insufficient heating capability

 

 

 

I am not clear what this warning is saying as the wording is "MIGHT"
have insufficient heating capability.  I too am getting this warning,
but I have very little unmet heating hours. Increasing the cfm/sq.ft
only increases total energy use but does not get rid of the warning.  It
seems to me it may be a software issue rather than a design issue?

 

 

________________________________

From: DongEun Kim <equested at gmail.com>
To: Carol Gardner <cmg750 at gmail.com>
Cc: equest-users at lists.onebuilding.org
Sent: Monday, July 25, 2011 7:12:44 AM
Subject: Re: [Equest-users] insufficient heating capability

Thank you Carol!

 

I modified "Min Design Flow(cfm/ft2) .

 

However, "insufficient heating" warning is keep showing. 

 

Only thing seems to work to solve this problem is to increase heating
capacity is Reheat delta T.

(Its system is VAV with Reheat).

 

What I can't understand the most is that specifying heating capacity of
main heating coil doesn't 

 

affect the heating capacity anyhow.

 

Any thoughts on this anyone???

 

Thank you!

 

DE

 

2011/7/25 Carol Gardner <cmg750 at gmail.com>

Hi DE,

If you look around at all the defaults you will probably find that
somewhere eQUEST is defaulting to 0.5 cfm/sf for your supply air. This
is often insufficient to meet your heating/cooling requirements. Things
I have done in the past to fix this is to use the same cfm/sf as the
proposed building uses, or look in the little ASHRAE Pocket Guide for
what they recommend for your building type. These two numbers will
likely be similar

Carol. 

 

On Sun, Jul 24, 2011 at 5:16 PM, DongEun Kim <equested at gmail.com> wrote:

Thank you John,

 

But isn't airflow supposed to be auto-sized if not specified?

 

I intentionally leave the flowrate blank to let the program calculate
the cfm that serves load the best.

 

Should still  I specifiy cfm?

 

DE

2011/7/23 John Aulbach <jra_sac at yahoo.com>

Try increasing airflow.

 

From: DongEun Kim <equested at gmail.com>
To: equest-users at lists.onebuilding.org
Sent: Friday, July 22, 2011 12:13 AM
Subject: [Equest-users] insufficient heating capability

 

Hi eQuesters!

 

Can anyone help me here?

 

I installed main heating coil as well as reheat coil with delta T=30.

 

Heating capacity and cfm is not defined so that they will be auto-sized.

 

And, I keep having this warning saying that the system "might have
insufficient heating capability."

 

I increased "Zone Entering Max Supply Temp", "Hot Deck Max Leaving
Temp."  But, the problem stays.

 

 

How do I increase the heating capability?

Thank you !!

 

DE

 


 

 

 

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-- 
Carol Gardner PE

 


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