ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Childrens safety outlets
by dsk - 06/25/22 04:07 PM
AC-DC stage Ultra-Fast charger, how it's made?
by libellis - 06/25/22 12:17 PM
Your favourite food?
by NORCAL - 06/16/22 12:06 AM
Price action trading with RENKO
by gfretwell - 06/15/22 02:08 PM
Please Help Wiring DCDC Buck Converter
by gfretwell - 06/15/22 01:58 PM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 41 guests, and 10 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
#41767 09/08/04 07:08 AM
Joined: Jan 2004
Posts: 79
C
cavo148 Offline OP
Member
How are commercial exhaust hoods wired for control where there's one unit for exhaust and another for incoming fresh air. Would the on/off switch be wired for them to come on at the same time or switched seperately? BTW, the one I'm looking at has a 3/4 HP exhaust and a 1/3 HP return motor. Thanks in advance.
Andy

#41768 09/08/04 10:56 AM
A
Anonymous
Unregistered
Andy, I usually set a control cabinet or control the motor starters / relays with a separate 120v control circuit to pull in the starter coils at the same time with one switch. In my area the incoming air is usually heated depending on outside temp as well so there is another coil.

Here is the rub. Most Fire Dept Inspectors in my area want the makeup air shut off and the Exaust Hood to start in any alarm condition in the space. You can drive a separate relay using aux power and alarm contacts in the FACP or have the FACP drive a control module if it's addressable.
I have a control drawing I could send as a JPEG file if you would like.

#41769 09/08/04 07:23 PM
Joined: Mar 2004
Posts: 947
T
twh Offline
Member
I thought the exhaust should not run without the make-up, because the exhaust alone can draw air down the chimney. I think the commercial make-up air units have an air proving switch, that locks out the exhaust.

#41770 09/09/04 09:41 AM
Joined: Dec 2003
Posts: 751
E
Member
And, for best comfort we want a slight positive pressure at all times to ensure minimal loss of unconditioned air.


Earl

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
HCE727
HCE727
Delaware County, PA, USA
Posts: 187
Joined: November 2005
Top Posters(30 Days)
triple 3
grich 2
dobler 2
Asset 2
Popular Topics(Views)
293,084 Are you busy
225,069 Re: Forum
210,491 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5