[Equest-users] VAV with Electric Reheat
Otto Schwieterman
oschwieterman at fhai.com
Fri Jul 23 10:22:05 PDT 2010
Omar,
I have a few comments. First of all, when I opened your file I got many
warnings stating that the windows were not positioned correctly. I am
using a modified eQUEST version of 3.63 supplied in a training from
Marlin Addison. You may not receive the warnings depending on what
version you are using. You may want to double check your window
placements.
I have provided screen shots of air handler 1. I made the following
modifications and it appeared to run correctly.
Also, I would recommend having an experienced modeler to review you
model when it is finished since this is your first one and there appears
to be many small items that could be improved.
Good luck,
Otto
From: Omar Katanani [mailto:omar at ecoconsulting.net]
Sent: Friday, July 23, 2010 12:48 PM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] VAV with Electric Reheat
Otto, it didn't work!
Dear all,
I discovered that the parameter "Hot Deck Max Leaving Temp" is necessary
in order to activate the main heating coil! If left to default, only the
reheat coils will operate.
Back to my case, where I had electric reheat. When I didn't specify the
"Hot Deck Max Leaving Temp", the hot water loop had zero flow because it
wasn't activated (and hence the error).
Now when I specified a value of 70F, I got rid of the error, but the
whole heating (99.9%) was electric, and a very small 0.1% was due to the
hot water loop.
A possible percentage of space heating sources is 80% hot water loop,
20% electric reheat coil. (or any other reasonable percentage).
I played a lot with the "reheat delta temp" and the "Hot Deck Max
Leaving Temp", the results slightly varied (change in the fuel
consumption of space heat, but still negligible compared to the electric
portion.
Any recommendations? I attach my files just in case...
Many thanks,
Omar
___________________________
Omar Katanani
Sustainable Design Engineer
Email: omar at ecoconsulting.net
EcoConsulting (Lebanon)
Nahas Building, 4th floor
4 St-Maron Street / Georges Haddad Avenue
Postal Code: 2028 5806 SAIFI
Beirut, Lebanon
Tel: +961 (0) 1 971 255
Mobile: +961 (0) 3 045 045
EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel: +44 (0) 207 939 0989
Fax: +44 (0) 207 939 0981
Website: www.ecoconsulting.net <http://www.ecoconsulting.net/>
-----Original Message-----
From: Otto Schwieterman [mailto:oschwieterman at fhai.com]
Sent: 21 July 2010 17:56
To: Omar Katanani; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] VAV with Electric Reheat
Omar,
You can try using a pre-heat coil as your hot water coil in the air
handler and the electric heat in your re-heat coil.
From: Omar Katanani [mailto:omar at ecoconsulting.net]
Sent: Wednesday, July 21, 2010 10:06 AM
To: Omar Katanani; equest-users at lists.onebuilding.org
Subject: [Equest-users] VAV with Electric Reheat
Dear all,
I'm sorry I've been nagging a lot lately, but believe me, you guys are
my only support!
I was using a VAV system, with the reheat source being the hot water
loop. I specified the Reheat delta temperature by trial and error to
25F. Everything is fine.
Now I got updated info from the client saying that the source of the
reheat is electric. I am getting an error message:
"Hot Water Loop has zero design flow. Check input for consistency, or
specify design loads."
I read a couple of discussions. I understand that many factors will
affect this issue. The "Hot Deck Maximum Supply Temp", the "Reheat Delta
Temp", and the "Zone Entering Max Supply Temp".
I tried specifying the hot deck max supply temp to 70F, I got the
results attached in the pdf. However, the gas consumption part of the
space heating is negligible compared to the electric, while I thought
both will be of significant ratios!
My main question is how to get reasonable results, knowing that the main
heating source is the hot water loop, and the electric reheat is to fine
tune the temperature of zones experiencing different loads or so...
I know that the design temperature of the zones is 70F, and that the
temperature that is supplied to the zone should be 30 degrees higher
than the zone temperature (70+30=100F).
Any advice on how to choose the "reheat delta temp" and the "hot deck
maximum supply temp", or any other input parameter you feel that it
affects, is greatly appreciated.
Many thanks,
Omar
___________________________
Omar Katanani
Sustainable Design Engineer
Email: omar at ecoconsulting.net
EcoConsulting (Lebanon)
Nahas Building, 4th floor
4 St-Maron Street / Georges Haddad Avenue
Postal Code: 2028 5806 SAIFI
Beirut, Lebanon
Tel: +961 (0) 1 971 255
Mobile: +961 (0) 3 045 045
EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel: +44 (0)207 939 0989
Fax: +44 (0)207 939 0981
Website: www.ecoconsulting.net
-----Original Message-----
From: Omar Katanani
Sent: Thu 7/15/2010 11:44 AM
To: equest-users at lists.onebuilding.org
Subject: VAV with Electric Reheat
Dear all,
I was using a VAV system, with the reheat source being the hot water
loop. I specified the Reheat delta temperature by trial and error to
20F. Everything is fine.
Now I got updated info from the client saying that the source of the
reheat is electric. I am getting an error message:
"Hot Water Loop has zero design flow. Check input for consistency, or
specify design loads."
I read a couple of discussions. I understand that many factors will
affect this issue. The "Hot Deck Maximum Supply Temp", the "Reheat Delta
Temp", and the "Zone Entering Max Supply Temp".
First of all, is the sum of the first two equal to the third?
My main question is how to get reasonable results, knowing that the main
heating source is the hot water loop, and the electric reheat is just to
fine tune the temperature of zones experiencing different loads or
so...
I played with all values but I can't figure out the pattern. I know that
the design temperature of the zones is 70F, and that the temperature
that is supplied to the zone should be 30 degrees higher than the zone
temperature (70+30=100F).
Any advice on how to choose the "reheat delta temp" and the "hot deck
maximum supply temp" is greatly appreciated.
Many thanks,
Omar
___________________________
Omar Katanani
Sustainable Design Engineer
Email: omar at ecoconsulting.net
EcoConsulting (Lebanon)
Nahas Building, 4th floor
4 St-Maron Street / Georges Haddad Avenue
Postal Code: 2028 5806 SAIFI
Beirut, Lebanon
Tel: +961 (0) 1 971 255
Mobile: +961 (0) 3 045 045
EcoConsulting (UK) Ltd
28 Marshalsea Road
London, SE1 1HF
Tel: +44 (0)207 939 0989
Fax: +44 (0)207 939 0981
Website: www.ecoconsulting.net
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