HVAC pros needed. Exhaust fan caused water heater to stop exhausting. DANGER

Hey guys. I have been getting CO2 spikes every time the hot water heater is burning. I checked the exhaust for the water heater and found it was not clogged, but it was drawing cool air into the house. Then I thought of my exhaust fan in the garden. So I opened a window and the downdraft from the water heater exhaust stopped immediately and it started to draw air out like it is supposed to. Also resolved by turning off the exhaust in my garden. It appears my exhaust fan in the garden is the cause and the only resolution is to have an open window so that the air will be drawn through it instead. I guess the place is pretty air tight so it started pulling air into the house through the water heater exhaust. Thing is that it's hot outside. It stays about 67 degrees in the basement because of the AC, but I suspect having open windows will increase the air temp of my garden since it will be pulling in 80-100 degree air into the basement.

Has anyone else run into this issue?
Seems very dangerous and everyone should be aware that this can happen. I wonder if it could also be causing a downdraft for the furnace. I have carbon monoxide detectors all over and they have never gone off, thankfully, my water heater appears to efficiently burn that crap off.

Any ideas on how to resolve without having to open a window. I thought about running an intake duct from outside into the closet that the water heater is in. Then hopefully it would draw the fresh air in from there and straight out so that the warm outside air does not increase inside temps.

Everyone please be aware that if your location is pretty air tight and you are running an exhaust fan, it needs to pull air from somewhere and in my case, pulled it down thought the water heater exhaust. If your water heater is not efficient then you could be releasing carbon monoxide into your home.

Thanks for any help. Good luck and be safe!

Carbon monoxide isnt created by hot water heaters untill almost all the oxegen is gone if your pulling in fresh air and exhausting i doubt it would harm you unless you constantly using hot water. Might as well set up your water heater to vent into your grow for added co2 yeah your exhausting and its not totally efficent but its co2 that should just go up its exhaust anyways.

^^ Bad advice.

Really? Do tell me what a co2 generator is. Oh right its a tankless hotwater heater

Is your vent cap on the water heater exhaust pipe damaged or bent? That was the number one problem that had to be fixed when I was an HVAC assistant, bad ventilation, high CO levels, etc. were all caused by a dented or damage vent cap.

A lot of older house don't have the right diameter pipe either.

If hes pulling enough air through exhaust to negatively prusser his place why would it kill him to vent the hot water heater directly into the grow if its just going to get sucked up anyways, the added co2 will only help. im not an HVAC guy but I work in the oil and gas industry and more than anything venting and fresh O2 is the key to saftey.

that article had clear words "malfunctioning unit" ie it was more than likely burning a yellow flame unlike the clean blue flame of a properly working unit. Anytime there is an instance of carbon monoxide poisoning I can be that there was more of a problem with low oxegen levels. CO is created through improper compustion or low oxegen levels(both the same in the end) a clean burning fuel such as LPG or natural gas put off a blue flame and give off water vapor and CO2 as a byproduct. you wanna get scared about a gas look up some facts on H2S

http://www.structuretech1.com/tag/backdrafting/

Backdrafting means that exhaust gases are spilling back in to the home, rather than going up the flue. A properly functioning water heater or furnace will not create high levels of CO, so you can’t say CO is coming in to the home unless you test the exhaust gases; we do this at every inspection. The video below shows me doing this. While backdrafting doesn’t mean CO is coming in to the home, this is still a potentially hazardous situation that requires immediate correction. Backdrafting has the potential to allow CO in to the home, and will always contain CO2 (carbon dioxide), which can cause sickness and headaches in higher concentrations.

If the back drafting issue is not taken care of and the water heater does begin to burn rich, then you have a problem. Its always better to correct all problems, not just wait for something worse to happen.

why would it backdraft if the water heaters vent line goes right to your room where its then sucked out through the exhaust line under constant suction(like an blower box). unless he is running the venting on a timer. wich then its just a buildup of co2 in your growroom to be sucked up the next time the venting turns on.

There was a guy a couple of months ago running a co2 setup off his hot water heater. lol we should check with him to see if hes dead before we argue anymore lol.

Im just interested how it would backdraft under suction? I wont say i know everything so its nice to get other views

brotherjericho said:

http://www.structuretech1.com/tag/backdrafting/

Backdrafting means that exhaust gases are spilling back in to the home, rather than going up the flue. A properly functioning water heater or furnace will not create high levels of CO, so you can’t say CO is coming in to the home unless you test the exhaust gases; we do this at every inspection. The video below shows me doing this. While backdrafting doesn’t mean CO is coming in to the home, this is still a potentially hazardous situation that requires immediate correction. Backdrafting has the potential to allow CO in to the home, and will always contain CO2 (carbon dioxide), which can cause sickness and headaches in higher concentrations.

If the back drafting issue is not taken care of and the water heater does begin to burn rich, then you have a problem. Its always better to correct all problems, not just wait for something worse to happen.

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wrong again!

your exhaust fan is sucking air out of the basement faster then the exhaust on your heater can push it out. Be careful you can have CO spikes not just CO2. Since your sucking out air it must be replaced some where they do make draft regulators that work on actuators

applepoop1984 said:

wrong again!

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Stalking is creepy.