Surprising Carbon Dioxide Levels - Using Recirculate on Long Trips

[Cujet]

Doesn't sound like you're in a pressurized cabin, or even well sealed.

Cessna 177RG, single engine. And you are 100% correct, not only is it unpressurized, but it has no form of fuselage seal. Exhaust gasses can follow the contour of the plane and sneak in every little seam, panel and even the landing gear wells. The door seals are intact, but they are not where exhaust can come in. The tailcone area is completely open to the fuselage internal space.

It seems that high power settings result in exhaust gas being directed away from the plane. Low power settings, no so much. I'm thinking exhaust flows up against the empennage.

 

[rstsco]

Cessna 177RG, single engine. And you are 100% correct, not only is it unpressurized, but it has no form of fuselage seal. Exhaust gasses can follow the contour of the plane and sneak in every little seam, panel and even the landing gear wells. The door seals are intact, but they are not where exhaust can come in. The tailcone area is completely open to the fuselage internal space.

It seems that high power settings result in exhaust gas being directed away from the plane. Low power settings, no so much. I'm thinking exhaust flows up against the empennage.

Reasonable conclusions.

Immaculately kept! Gorgeous! I'm assuming the picture was taken during an annual?

 

[rstsco]

On our 18-hour trip to Wisconsin yesterday, I tested the CO2 levels after having the recirculate on for an extended period of time. I turned on the monitor and it quickly started climbing, then slowed as it went over 1400ppm. I stopped the "experiment" at 1454ppm before the alarm would have gone off at 1500ppm.

I turned the recirculate off, and over the next 15-30 minutes, the CO2 level dropped to 623ppm before I powered off the monitor. Later I turned the recirculate back on, then back off again after the value climbed to over 1000ppm.

The article which warned of high levels of CO2 in a vehicle while staying in recirculate was validated in my mind. Maybe not the most tightly-controlled environment, but learned a valuable lesson. My relationship and interaction with the recirculate button has changed.

I can honestly say I didn't expect the outcome to be as "dramatic" as I saw yesterday.

 

[Owen Lucas]

Interesting article related to CO2:

• Attendees actively utilized the real-time dashboard to assess their personal risk, prompting many to mask up or move to better-ventilated areas when the monitors indicated high CO2 levels.
• The successful deployment demonstrated that accessible, low-cost DIY technology can effectively bypass older venue limitations to provide critical public health data during ongoing viral outbreaks.
• The system relied on the scientific finding that CO2 levels are a proxy for pathogen risk, as high concentrations indicate poor ventilation where airborne viruses can linger in the "breath backwash" of others.

https://arstechnica.com/security/20...talled-a-literal-antivirus-monitoring-system/

 

[oil pan 4]

1,500 is nothing. I would breathe 7,000 to 8,000ppm for hours when working on the dry ice machine at my last job. Around 8,000ppm you do start to feel it.

 

[OilStained]

Didn’t read all pages, but good indeed.

 

[oil pan 4]

Is fine until you hit about 7,000ppm and then start encountering carbon dioxide toxicisity effects, hypercapnia.
I was in the red plenty of times but only felt like mild symptoms. Your milage may vary.

 

[alarmguy]

4 people are 3 dogs in the house Christmas as we hit 1140 PPM CO2, highest ever however the weather is warm HVAC hasn't been running as much..

Typically, when just the wife and I never more than 850. Been running closer to 550-650 max with the cold weather. I was starting to think it was broken until guests arrived snd are staying over, then shot up into territory I never saw before. My explanation for that would be the HVAC in the cold runs 18plus hours a day, it has an air exchanger that craws in fresh air when it runs couple with the extra guests and 2 extra dogs.
Still over 1000 right now at 10:40pm

 

[alarmguy]

Ok, new record day after Christmas evening.
Company total - 6 adults and 3 dogs.

 

[ProbeGT]

Neither. Upstairs bedroom converted to my home office. With the window open, readings in the 400s. Close the window with the door closed and eventually climbs to 1200+. Laptop, external monitor, ceiling fan, and my breathing only thing in the room. Since it's summer, the central air runs often.

How tall are your ceilings? I'm also in central TX. When I looked for a house, one of the criteria was tall ceilings, knowing the AC would be on most of the time with windows closed. I have 14ft ceiling in the main living area and 12ft ceilings in the bedrooms. I wonder if this helps the CO2 level and also how much ceiling fans help reduce the CO2 levels, given that CO2 is heavier than air and settles down.

 

[WeyounDS9]

Yep, I rarely use recirc. Usually only if its 90*+ and first getting into the car to help cool it off better.

Same here and for same reasons described.

 

[rstsco]

How tall are your ceilings? I'm also in central TX. When I looked for a house, one of the criteria was tall ceilings, knowing the AC would be on most of the time with windows closed. I have 14ft ceiling in the main living area and 12ft ceilings in the bedrooms. I wonder if this helps the CO2 level and also how much ceiling fans help reduce the CO2 levels, given that CO2 is heavier than air and settles down.

Our ceilings are mostly 10' downstairs and 8' upstairs with a large opening at the stairs all the way from top to bottom. It's nothing special except half of our neighbors are still here after 25 years!

 

[alarmguy]

Follow up from post #89
We have our house back, no more company/visitors and two less dogs.
Just wife, I and a miniature poodle.
Last night ... down almost 1000 PPM from post #89

This morning but in all fairness, cold front came through and HVAC is running a lot so a lot of air exchange taking place.

 

[alarmguy]

How tall are your ceilings? I'm also in central TX. When I looked for a house, one of the criteria was tall ceilings, knowing the AC would be on most of the time with windows closed. I have 14ft ceiling in the main living area and 12ft ceilings in the bedrooms. I wonder if this helps the CO2 level and also how much ceiling fans help reduce the CO2 levels, given that CO2 is heavier than air and settles down.

If it is a newer house you may have an air exchange system in the HVAC. We do as posted above