[Equest-users] VAV with Electric Reheat

[Omar Katanani]

Dear all,

Hope you had a relaxing weekend!

Is there any way that I can enter the capacity of the electric reheat coils?
There is this input parameter called "Heating Capacity". I guess it is for the whole AHU, right?

The issue is that I'm not able to figure out how to model the VAV with electric reheat, as there are many temperatures that I'm asked for including "Reheat delta Temp", "Zone Entering Max Supply Temp",  and "Hot Deck Max Leaving Temp".

If I left everything to default values, I get an error of "Hot Water Loop has Zero design flow.."

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: Fri 7/16/2010 9:35 AM
To: John Aulbach; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] VAV with Electric Reheat
 

John,
The primary heating coil in the air handler operates on the hot water loop.
It is just the terminal units that have an additional electric resistance coil that is used in the cooling season to raise the air temperature of the zone if the internal loads of the zone drop for some reason.

That's why I need the both the hot water loop and the electric resistance.

Best,
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: John Aulbach [mailto:jra_sac at yahoo.com]
Sent: Fri 7/16/2010 2:11 AM
To: Omar Katanani; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] VAV with Electric Reheat
 
 You have an electric heating system !!  There IS no hot water flow !! Get rid 
of the hot water loop !!

John Aulbach




________________________________
From: Omar Katanani <omar at ecoconsulting.net>
To: equest-users at lists.onebuilding.org
Sent: Thu, July 15, 2010 1:44:24 AM
Subject: [Equest-users] 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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