Negative Pressure in my House Causing Carbon Monoxide to pull down the Chimney..HELP!

If your grow room is in your basement then you need to isolate the intake to stop the negative pressure on the rest of your house. If you have a gas water heater or furnace then there should be at least 1-2 fresh air intakes (usually at different heights) There are there to provide fresh air to the furnace and pilot light for your gas water heater. Do not pull air from within your upstairs to pull downstairs, that's part of the problem. You want to pull fresh air in from outside into the room that your furnace and water heater are in and then pull some of that air into your grow room. This forces the all the intake air to come in from the same path it normally would for the furnace and water heater, but at higher volume. If the furnace room has it's own entrance this is optimal, as the air pulls into that room directly then onto your grow. If I have time I'll try to draw up a diagram as I have already done this successfully without issues for years now. ; )

And NOBODY should have any gas appliances, heaters or furnaces in the home without multiple Carbon Monoxide detectors in the house! That's just crazy!

heat rises bro so if your intaking air from the second floor the air will already be warm to begin with

I had the intake in the basement to begin with (cooler air) but with the gas boiler and water heater also in the basement i figured pulling air from the second floor would solve the problem with the chimney...i was wrong.

Are you saying i should have a passive intake in the basement that pulls the cold air in from outside?Its winter where i live??Could i just open a basement window?Still its winter here??My boiler and water heater room is framed (2x4) and insulated but no door installed yet or drywall etc just rough framing.and my basement is a walk out if that helps.

Thanks i appreciate the help,a drawing would be great! And for sure on the Carbon Monoxide dectors i have had several the entire time i lived here but they just recently went off!!needless to say my fans wont be turned back on until i find a solution.

medgrow6006 said:

I had the intake in the basement to begin with (cooler air) but with the gas boiler and water heater also in the basement i figured pulling air from the second floor would solve the problem with the chimney...i was wrong.

Are you saying i should have a passive intake in the basement that pulls the cold air in from outside?Its winter where i live??Could i just open a basement window?Still its winter here??My boiler and water heater room is framed (2x4) and insulated but no door installed yet or drywall etc just rough framing.and my basement is a walk out if that helps.

Thanks i appreciate the help,a drawing would be great! And for sure on the Carbon Monoxide dectors i have had several the entire time i lived here but they just recently went off!!needless to say my fans wont be turned back on until i find a solution.

Click to expand...

Exactly what I'm saying- If you have a gas water heater and furnace then I'm pretty sure code dictates you have a minimum of of least one 8" fresh air intake in your furnace/ water heater area to supply fresh air to those units. Look around, you should see one near the ceiling pointing downwards and another that almost goes to the floor. This balances out the draw they pull in from outside. If you are pulling in air from outside, yes it will be cold, but will also help cool your room down. It's winter where I live as well and have yet to have any problems doing this. Your furnace and or water heater should already be doing this (depending on the type). My room temps stay around 68-72 degrees year round...and without A/C.

If you have a window in the grow area that could be opened, you can crack it open 2-3 inches, board it over and install a very short section of intake ducting to that board (equiv to your exhaust fan dia. 8") maybe a 6" length then install a closeable/adjustable flange that you could use to throttle the intake air flow... close it most of the way when its really cold or hot and open it up when its tolerable for max air exchange. Im no expert so I dont know the exact proper names for the duct pieces, but Im battling heat also (my AC kicked on today... Jan1 and it was 83 out) and Ive been to Home Depot and found all the parts to make and do the same thing. As long as your grow room is properly sealed to the rest of the house, and it has its own intake/exhaust, the neg pressure inside will not affect the rest of the basement until you open the door, then there may be less resistance for air to come through the water heater exhaust than your mostly closed intake. If the intake is wide open, it will still be easier to flow through that intake than the water heater exhaust when you have the grow room door open. Just my stoner creativity picturing this in my head but not having the tech knowedge to give exact names lol.

Why are you exhausting the air out of the house in the first place? It will save on your heating bill, and if you vent outside 1.) your exhaust is able to be seen by infrared 2.) your losing all the great oxygen that your garden is producing to make the air in your home cleaner.

As long as you have some kind of smell filtering you shouldn't have a problem. And if you are pulling and venting within the same overall chamber you shouldn't have any more negative pressure.

I agree about venting into the basement to save heat but if you don't want to do that, finish the boiler room off & put a passive intake in it. you dont need to drywall. a layer of plastic around the 2x4 framing would work(and a layer for the door). add a dryer vent in the room to allow fresh air in & you should be fine.
cracking a window in the basement should work as a short term fix.Yes I know its winter(I expect 5-10 in of snow tonight) the trick is to make it easier for air to flow into your house than being sucked down the chimney.

Simple physics my friend. You are pulling air out of the house so you have to let air in. Opening a window is the easiest. Installing a vent pipe with a flapper would be the best bet. I would NOT T into the fresh air furnace intake. Disrupting the pressure gradient in this intake could cause your furnace to operate poorly. The most efficient way to do it would be to install some ducting from the outside directly to your veg or flower room and then put your 8" exhaust fan on a temperature control module. You don't need to always be exhausting to keep co2 levels high. When the room heats up the fan will turn on drawing cool air to reduce temperatures and supply fresh co2. This is the most advantageous as now your actually controlling the temps as opposed to crossing your fingers and relying on outside temps. There will be a tiny amount of negative pressure as the ducting will have more resistance than your fan but it shouldn't pose that big of an issue. The only way to be absolutely sure you have positive pressure, which may be a good idea since your house is very tight, is to... Wait a minute. Ok, scratch the new inlet idea. Flip your exhaust fan around and put a temp controller on it. Booyah, problem solved. You get climate control, your not blowing warm smelly air outside, and your controlling temps. The positive pressure your creating will exit the home through your chimneys.

Just put an intake fan from the outside, exhaust in the house. That's what I would do to save money on heating the house up etc. Plus you get nice air from plants.

Simple physics my friend. You are pulling air out of the house so you have to let air in. Opening a window is the easiest. Installing a vent pipe with a flapper would be the best bet. I would NOT T into the fresh air furnace intake. Disrupting the pressure gradient in this intake could cause your furnace to operate poorly. The most efficient way to do it would be to install some ducting from the outside directly to your veg or flower room and then put your 8" exhaust fan on a temperature control module. You don't need to always be exhausting to keep co2 levels high. When the room heats up the fan will turn on drawing cool air to reduce temperatures and supply fresh co2. This is the most advantageous as now your actually controlling the temps as opposed to crossing your fingers and relying on outside temps. There will be a tiny amount of negative pressure as the ducting will have more resistance than your fan but it shouldn't pose that big of an issue. The only way to be absolutely sure you have positive pressure, which may be a good idea since your house is very tight, is to... Wait a minute. Ok, scratch the new inlet idea. Flip your exhaust fan around and put a temp controller on it. Booyah, problem solved. You get climate control, your not blowing warm smelly air outside, and your controlling temps. The positive pressure your creating will exit the home through your chimneys.

Great idea legallyflying(just said why didnt i think of that)i will just reverse my exhaust fan so its my intake,only prob is i do not have anything for smell control since its a legal grow and where i live i dont have close neighbors.Ive always vented outside only using good furnace filters.Looks like ill be shopping around for this stuff since i dont want my house to smell any more than it already does.

MacGuyver420: I have a boiler with water baseboard heat exchangers,there has never been an intake near my boiler and hot water heater since ive lived here but it sure makes sence that it should so im also going to finish that room,put a door on and install a 8" passive intake.


Undercover:i dont have any windows in or near my grow room but that is a great idea!

mrmadcow: I cracked the window in the basement and the second floor as a temporary fix this morning..so far so good.

I also went out and purchased 2 more carbon monoxide detectors with digital readouts so i can monitor the ppm levels..happy to say they are at 0.Makes a total of 5 in my house.I appreciate all the tips and tricks!+ rep to you all

MacGuyver4.2.0 said:

If your grow room is in your basement then you need to isolate the intake to stop the negative pressure on the rest of your house. If you have a gas water heater or furnace then there should be at least 1-2 fresh air intakes (usually at different heights) There are there to provide fresh air to the furnace and pilot light for your gas water heater. Do not pull air from within your upstairs to pull downstairs, that's part of the problem. You want to pull fresh air in from outside into the room that your furnace and water heater are in and then pull some of that air into your grow room. This forces the all the intake air to come in from the same path it normally would for the furnace and water heater, but at higher volume. If the furnace room has it's own entrance this is optimal, as the air pulls into that room directly then onto your grow. If I have time I'll try to draw up a diagram as I have already done this successfully without issues for years now. ; )

And NOBODY should have any gas appliances, heaters or furnaces in the home without multiple Carbon Monoxide detectors in the house! That's just crazy!

Click to expand...

yea make a diagram

Whats up everybody!Just thought id update everyone on what i did to solve the problem.Ok so i switched my 8" exhaust fan around so its now the intake and put it on a temp controller.I then flipped around the 6" intake to make it the exhaust and added a Phresh filter carbon scrubber and it now exhausts into the basement.As a bonus its heating my basement when the lights are on and i cant smell a thing!Thanks for all the help!!

Awesome! I just installed a similar setup to cool my rroom in the ccolder months instead of using my air conditioner. It exhausts my co2 every hour or so but at least I'm not running an air con in January, that is just ridiculous.

Now, there is only one thing you must do and that is to screen the intake and exhaust!! When spring comes the bugs will be dying to check out your new strains! Because those mushroom filters are so expensive I built a little plywood box around the outlet and taped air furnace Air filter to it. Final step, I misted it with neem oil

Its an awesome setup and it doesnt hurt to save on the elec. bill!I have a window screen covering the outdoor intake(modified dryer vent)and a furnace filter covering the fan in the room and have a carbon scrubber on the exhaust fan.