makeup air dumper to range hood

Every system with a make-up-air fan that I have wired has had a larger exhaust motor, fan, and duct.
 
Makeup air should be introduced so that it enters the airflow in a way that assists heat and fume removal. Some commercial setups are hideously complicated, with sensors and heat recovery schemes galore. Even in 100F summer weather, if your hood is vented to the rear, if the makeup air plenum is right at the front face of the hood, you aren't going to be in the makeup air stream and suffer any discomfort.
 
 
infinity said:
This means that the hood had a control circuit/contact for the makeup air that only turned on at a certain fan speed.
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Motors used to use a centrifugal switch to close contacts at a higher speed, can this happen here?
 
LarryFine said:
The first installation pic shows what I suggested in post #24.
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I spoke to my HVAC contractor about this and he told me that it can be installed directly into the AC system return. Since the system has open ductwork the unit does not even need to run when the damper is open.

In my application the AC unit is in the attic so a roof cap would be installed in the roof with a section of duct>damper>filter>return air on unit. A pressure switch at the hood to signal the damper to open.

One note on the Broan makeup air system it can only be used for Broan exhaust fans.
 
infinity said:
I guess that would work if you also had hot air heat. Not going to work for AC only.
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It would still pull air through the ductwork, just won't provide additional conditioning of the incoming air. Even heat and cool systems won't condition the air if thermostat isn't calling for system to run at the time. There are some places that are already implementing fresh air intake and bringing it in through return air ducts. The tighter they make these buildings the more need there is to loosen them back up some so that there is some fresh air coming in:unsure:
 
kwired said:
Even heat and cool systems won't condition the air if thermostat isn't calling for system to run at the time.
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My system is AC only so I'm not thrilled with the prospect of having unconditioned air flowing through it especially in the dead of winter when the temps are in the teens and single digits. There are three ceiling mounted AC supply ducts within about 12' of the hood so that cold air will be pulled across the room.
 
infinity said:
I spoke to my HVAC contractor about this and he told me that it can be installed directly into the AC system return. Since the system has open ductwork the unit does not even need to run when the damper is open.

In my application the AC unit is in the attic so a roof cap would be installed in the roof with a section of duct>damper>filter>return air on unit. A pressure switch at the hood to signal the damper to open.

One note on the Broan makeup air system it can only be used for Broan exhaust fans.
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Unless the unit has an enthlapy damper, how are they making the air up using the return? The whole idea is to not creating a negative pressure in the building, and sucking air from the return does not do that, unless fresh air from the outside is brought in through the hvac system.
 
hillbilly1 said:
Unless the unit has an enthlapy damper, how are they making the air up using the return? The whole idea is to not creating a negative pressure in the building, and sucking air from the return does not do that, unless fresh air from the outside is brought in through the hvac system.
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Yes that's what I said, the fresh air from roof vent gets connected to the AC unit return duct.
 
hillbilly1 said:
Ok, I misunderstood, I thought it was connecting the make up air connection at the hood to the return, Sorry! I’m used to commercial hoods!
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No problem. I was surprised when he told me that's typically how they do it. Just opens a pathway through the existing duct work for the fresh air to come in.
 
Malywr said:
Hi everyone I need help how to wire makeup air dumper to range hood over 400cfm When hood is ON make up dumper must open. Or I should temper with range hood and install same size wire as power supply to hood and run it to dumper? or use current transformer next to electrical panel that will detect when hood is energized currently transformer will energize dumper I font want to over complicate something what suppose to be simple


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www.aircycler.com

RangeRelief™ Rangehood Pressure Sensor

CONTRACTORS CONTACT US FOR PRICING Item # Product Description AC-RR RangeRelief Rangehood Pressure Relief Control Switch AC-RR-4 RangeRelief Rangehood Pressure Relief Control Switch + 4
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my company offers a product that might help. Powered with a door bell transformer typically.
 
Jasonw said:
www.aircycler.com

RangeRelief™ Rangehood Pressure Sensor

CONTRACTORS CONTACT US FOR PRICING Item # Product Description AC-RR RangeRelief Rangehood Pressure Relief Control Switch AC-RR-4 RangeRelief Rangehood Pressure Relief Control Switch + 4
www.aircycler.com www.aircycler.com

my company offers a product that might help. Powered with a door bell transformer typically.
Click to expand...

Thank you
And thank you everyone for great feedback and links


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So I've been following up on this MUA dilemma. I reached out to the NJ DCA code assistance team with the question and some of the information posted in this thread. Here's the question and response. The response isn't overwhelmingly positive.

Question:
I'm in the planning stages of installing a new kitchen. Part of that planning includes a new range hood system. As an electrician I'm familiar with the requirement for make up air (MUA) once the exhaust unit exceeds 400 CFM. The new system would be either a 600 or 1000 CFM system.
I've reached out to my HVAC contractor and he has informed me that he has been installing a passive fresh air intake system into the existing central AC system for MUA. This consists of a roof cap, an electric damper, and duct work that is connected to the existing return air duct of the AC system. When the exhaust fan is turned on the remote damper opens and allows the fresh air to enter the system providing the MUA within the structure. Is this type of system code complaint?

I've asked both electrical contractors and HVAC contractors and have gotten varying opinions as to what is acceptable under the NJ UCC. Some say that a fan forced air MUA system is required, others say that the passive air into the AC system is sufficient to comply with the code. Any insight that you can provide would be greatly appreciated.

Response:
Rob,

What you are describing sounds code compliant.
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infinity said:
So I've been following up on this MUA dilemma. I reached out to the NJ DCA code assistance team with the question and some of the information posted in this thread. Here's the question and response. The response isn't overwhelmingly positive.
Click to expand...
Its is a interesting topic, glad to see you tried to get actual feedback from the AHJ. In light commercial work I think i have usually seen the passive damper on drawings. I think the fan forced system is for larger buildings, like healthcare where you want to maintain a positive air pressure in the building or there is a need to restrict air movement in and between various departments in a building.
 
tortuga said:
Its is a interesting topic, glad to see you tried to get actual feedback from the AHJ. In light commercial work I think i have usually seen the passive damper on drawings. I think the fan forced system is for larger buildings, like healthcare where you want to maintain a positive air pressure in the building or there is a need to restrict air movement in and between various departments in a building.
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Yeah there seems to be the written code requirement and then there's the enforcement. My brother built a new house in the next town over with a 600 CFM kitchen range hood and no one ever asked or checked to see if was 400 CFM's or less.
 
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