Ventilation drawing air from furnace

BigGreenThumb and thumper60 are spot on, there's no rigging anything.

You have 3 options...

1: Vent your exhaust back into the house and deal with the extra humidity and have no concerns of backdrafting from the furnace.

2: Crack a window somewhere else in the house, hopefully allowing the air to be somewhat conditioned before hitting the grow room, and having no worries about backdraft

3: Get a high efficiency furnace, they have their own ducting for outside/combustion air, meaning it won't be starving for air when running the exhaust outside the house.

For the record, just running the hood vent above my stove and a bathroom exhaust fan at the same time creates backdrafting/CO issues if the furnace is running.

Best wishes and be safe.

Booga said:

i think i understand, im gonna try rig something up tomorrow. thanks everyone for the input

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Definitely find a solution. CO is nothing to play around with. If you're triggering alarms I'd shut off the fans until you can get things resolved. That's me. But if you're triggering the CO alarms you have too much CO. No plants worth risking your life over.

gonna vent it back into the house and hook up my dehumidifier. gonna put all my alarms near by while i attempt messing with it just to be safe.

A question

do you happen to have a gas water heater in the same area
If so does it vent with steel pipe?
Just trying to get a handle on that co2 spike

yes the water heater is gas and is venting out a steel pipe and is right next to the furnace

Ok
It has a design where it lets it backdraft till the chimney warms or if you create a suction in that room it will pull straight into your room
Especially if it has a standing pilot
That means you can’t do what you are trying to do in that area
As a rule if you can it would end the co2 spike after a few minutes

Booga said:

its only when i close up the 4" hole im using for intake that the alarm goes off. dont think i can get a hvac guy in here unfortunately. the room the tents are in is surrounded by cement besides one wall that leads into the furnace room. the only other place i could get air from also shares a wall with the furnace area, i dont think it would solve the problem.

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Where is the air intake for the furnace? Air like water and following the path of least resistance. Sounds like this hole is the major intake. Intended or not.

Herb & Suds said:

Ok
It has a design where it lets it backdraft till the chimney warms or if you create a suction in that room it will pull straight into your room
Especially if it has a standing pilot
That means you can’t do what you are trying to do in that area
As a rule if you can it would end the co2 spike after a few minutes

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so would the problem persist if i was to vent to a different room inside the basement?

Booga said:

so would the problem persist if i was to vent to a different room inside the basement?

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It’s all about where the intake is coming from
It is causing negative pressure when you close window and seeks the path of least resistance to get air

hotrodharley said:

Where is the air intake for the furnace? Air like water and following the path of least resistance. Sounds like this hole is the major intake. Intended or not.

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the furnace has a 4 inch pipe that runs outside for an air intake at least i think thats the furnace intake

Booga said:

the furnace has a 4 inch pipe that runs outside for an air intake at least i think thats the furnace intake

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Nope it is the vent if it’s metal
Now pvc is a different story

I have the same hot water tank,furnace combo.I run my cold air in a insulated 4" hose same as you through a window that's boarded up.I run it about 25' into my furnace room along with the other cold air intake for furnace.So I have two 4" cold air in.

Booga said:

so would the problem persist if i was to vent to a different room inside the basement?

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Venting within the basement will solve your issue

myke said:

I have the same hot water tank,furnace combo.I run my cold air in a insulated 4" hose same as you through a window that's boarded up.I run it about 25' into my furnace room along with the other cold air intake for furnace.So I have two 4" cold air in.

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I think OPs tent is IN the same room as the furnace so this wouldn’t work in that scenario

my tent is in the room next to the furnace room in a sort of crawl space/cold room, window is in the furnace room.
im thinking for now im going to just exhaust into the basement and get my dehumidifier going.

Noodles42 said:

Run ductwork for the passive intake in from another room?
But if your detector is going off, I'd call an hvac guy. It shouldn't be doing that.

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Booga said:

i think i understand, im gonna try rig something up tomorrow. thanks everyone for the input

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If he's depriving combustion from oxygen , the alarm should go off from CO produced ( incomplete combustion), I would think..

Booga said:

my tent is in the room next to the furnace room in a sort of crawl space/cold room, window is in the furnace room.
im thinking for now im going to just exhaust into the basement and get my dehumidifier going.

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AS long as you dont vent outside there will be no pulling air the air pressure will be even should be fine, I installed gas heaters for many yrs. An i bet that co is coming from the W/H not the furnace.

Booga said:

my tent is in the room next to the furnace room in a sort of crawl space/cold room, window is in the furnace room.
im thinking for now im going to just exhaust into the basement and get my dehumidifier going.

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With the furnace running would you even need a dehum? My room drops from 50% lights on to 30% an hour after lights off from the furnace.

myke said:

With the furnace running would you even need a dehum? My room drops from 50% lights on to 30% an hour after lights off from the furnace.

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Too many variables
Block houses
Crawl spaces
Full basements
Slabs
All bring humidity

Herb & Suds said:

Too many variables
Block houses
Crawl spaces
Full basements
Slabs
All bring humidity

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With it so cold furnace runs full time,sounds like he has a full bsmt like me.I have to run humidifiers even with outside RH above 60%. Forced air furnace just eats up humidity.