Incomplete combustion or oxygen deprivation?

[rerod]

Just wondering after cutting in many fresh air intakes.. Has anyone ever experienced or even heard of a case of incomplete combustion or low O2 levels due to a one pipe furnace or water heater using up all the 02, other than in theory?

I've heard of people dying from CO poisoning, but never oxygen deprivation, and Ive found many fresh air intakes blocked off by the home owner which never made anyone sick that Im aware of..

Thanks

 

[danski0224]

The house is not sealed well enough for that to be a problem.

The general exception would be passive houses, or other ones where extreme detail was paid to seal up air leaks. But then, those places will have forced ventilation to meet code.

 

[Jackfre]

I don’t peruse those type statistics, but in addition to staying at a HI last night, over the years I represented Selkirk, Dura-Vent, Z-Flex and Tjernlund, etc so solid fuel/gas/oil/pellets. Tjernlund was power venters, ventilators and combustion air Enforcers. Pretty much everything. As the Rep you get the problem calls, so many site visits over the years to try to pin the tail on the donkey. Almost universally, zero to poor to improper combustion air was the main or strongly contributing factor. A couple things I learned. This being in New England, the land of full basements, a contractor would look at the open expanse of the new empty basement and not realize that there are people who will fill 75% of that cubic space with…stuff. The other thing is that about 20 minutes after the homeowner moves in he is dragging a pile of 2x’s down the bulkhead door to build a wall around the boiler. What Me Worry? It was almost good enough day one. Day two? The other thing, and this has been useful. In a full basement it was common to have a cold air supply pipe to the floor in the mech area. It would have a return bend at the bottom, so facing up. I solver the life long mystery of the “missing Sock.” They are all in that combustion air pipe. No lie! People block them up because they are spilling cold air all winter 24/7. On non-sealed combustion air systems I am a big proponent of the Tjernlund Enforcer. It ties into the burner control and only provides air on a call for heat. When the stat is satisfied it shuts down. Field’s Fan-in-a-Can is its competitor. Tjernlunds is better, imho.
Again I cannot comment on CO death statistics, but if you have been the rare birds who pipes in proper air you are to be commended. Keep it up. Inadequate CA on an open system does affect interior air quality and over time we know that is unhealthy.

 

[rlitman]

... I've heard of people dying from CO poisoning, but never oxygen deprivation...

Air starts out at around 21% oxygen. That's 21 parts per hundred, or 210000 PPM of oxygen. The death zone at 8000M elevation has 34% of the oxygen at sea level. So let's say that down to 71400 PPM of oxygen, you should be ok.

Air start out at around 0.04% CO2. That's 400 PPM, but CO2 would be immediately dangerous at around 40000 PPM. So, you'll run up the CO2 to lethal levels before you run out of oxygen.

Carbon monoxide is lethal in minutes at 10000 PPM (long term, it's dangerous at far lower levels). So, you'd reach lethal levels of CO first, because as oxygen levels in an enclosed space are depleted, combustion trends towards incomplete, favoring production of CO over CO2.

Oxygen deprivation happens, but it's not normally something you'd see in a home.

 

[fitter30]

ERV and HRV were design for tight building for sick building syndrome where the air quality gets bad. Blower door test will tell how tight a house is. Newer build that is
tight and energy efficient hopefully wouldn't scrimp on not running fresh air to furnace and water heater but if they would and short on O2 burner would soot up or trip on roll out safety.

The sick building syndrome

The sick building syndrome comprises of various nonspecific symptoms that occur in the occupants of a building. This feeling of ill health increases sickness absenteeism and causes a decrease in productivity of the workers. As this syndrome is increasingly ...

www.ncbi.nlm.nih.gov

 

[rerod]

Yeah, I didn't think anyone actually had passed from oxygen deprivation due to the lack of a combustion air intake. 4 decades working in hvac, and Ive seen my share, but Ive also never seen gas appliances starved of oxygen either.. I imagine that situation is more common.

Tjernlund In forcer.. Neat, but a bit much for a regular home imo. A tight home would probably have a two pipe +90 furnace. But light commercial with multiple furnaces and water heaters.. Yup.

Is the only difference between a regular residential furnace and a mobile home furnace this combustion air the MH furnace has built into the flue?

Thanks everyone.

 

[brewchief]

Yeah, I didn't think anyone actually had passed from oxygen deprivation due to the lack of a combustion air intake. 4 decades working in hvac, and Ive seen my share, but Ive also never seen gas appliances starved of oxygen either.. I imagine that situation is more common.

Tjernlund In forcer.. Neat, but a bit much for a regular home imo. A tight home would probably have a two pipe +90 furnace. But light commercial with multiple furnaces and water heaters.. Yup.

Is the only difference between a regular residential furnace and a mobile home furnace this combustion air the MH furnace has built into the flue?

Thanks everyone.

I've run across a couple jobs that a water heater wouldn't vent because of the lack of make up air in the furnace room, a poorly sealed return or large leaks around the air filter can also be contributing factors. I think most of the time when there is a CO problem it's due to multiple problems, for example a failed heat exchanger creating CO with the exhaust termination to close to a fresh air intake.


Every gas appliance I've seen that was rated for mobile home use could be converted from natural gas to lp with a simple orifice swap and flipping a regulator cap over or some other simple way to change gas pressure without needing to actually check the pressure. At one time carrier/bryant sold a conversion kit for some of there normal 90+ furnaces that made them mobile home rated, it was a gas valve with a flip over cap for the regulator.

 

[danski0224]

Tjernlund In forcer.. Neat, but a bit much for a regular home imo. A tight home would probably have a two pipe +90 furnace.

Problem is that the installers and/or the customers do not do the 2 pipe option to save money. There are a LOT of 1 pipe installs out there.

Then there are all of those so-called "high efficiency" water heaters with a PVC vent, that are just using a **** ton of indoor air to dilute the flue gases to a temperature low enough to use a PVC flue.

Combustion air code as written just invites combustion air ducts that are stuffed with insulation as soon as the certificate of occupancy is awarded.

And don't forget about the basements that get finished on the sly, with the walls built right next to the mechanical stuff, and a solid door.

 

[danski0224]

I think most of the time when there is a CO problem it's due to multiple problems, for example a failed heat exchanger creating CO with the

Yes.

exhaust termination to close to a fresh air intake.

Then that installation is not to code and would not pass an inspection.

I mean, there are like 4 pages in the instructions dedicated to where the flue can and can't go, plus all of the stuff about lengths and elbows.

Yeah, people don't read it.

It ***** because obviously there are so-called "professionals" out there doing ****** installs just like the DIY crowd that doesn't know what they are doing, either.

While not a flue problem, I just ran across a high velocity AC system that was not installed properly at all. And it was done by the biggest company in my area that specializes in those systems. It wasn't done recently, but still.

 

[rerod]

I've run across a couple jobs that a water heater wouldn't vent because of the lack of make up air in the furnace room, a poorly sealed return or large leaks around the air filter can also be contributing factors. I think most of the time when there is a CO problem it's due to multiple problems, for example a failed heat exchanger creating CO with the exhaust termination to close to a fresh air intake.


Every gas appliance I've seen that was rated for mobile home use could be converted from natural gas to lp with a simple orifice swap and flipping a regulator cap over or some other simple way to change gas pressure without needing to actually check the pressure. At one time carrier/bryant sold a conversion kit for some of there normal 90+ furnaces that made them mobile home rated, it was a gas valve with a flip over cap for the regulator.

Thanks.

I think Im going to buy a 80% furnace next, with all the issues Ive read about secondary's and boards failing due to voltage irregularities. My blower module in my infinity failed and was going to cost 3 grand to replace, but I fixed it soldering in a 4 dollar thermister. Not much savings when repairs costs thousands, but that's another discussion.

And I'm thinking another 80% furnace for my second rural property with propane, but that would be the secondary heat after the 3 separate mini split heat pumps stopped heating during the next polar vortex.. But I cant find a upflow gas MH furnace so that I can relocate the duct work.

 

[Walkers]

Yeah, I didn't think anyone actually had passed from oxygen deprivation due to the lack of a combustion air intake. 4 decades working in hvac, and Ive seen my share,

Nah, they pass from the resultant fire from the flame roll out burning down the house. This is generally on much older equipment though. I did many fire investigations on houses, not much to investigate on mobile homes after they burn though.

 

[PelicanPines]

Reason to have houseplants.

 

[rerod]

Nah, they pass from the resultant fire from the flame roll out burning down the house. This is generally on much older equipment though. I did many fire investigations on houses, not much to investigate on mobile homes after they burn though.

Ah, so you got to see the aftermath.. My work never burnt any place down thank god, except almost when I was welding class a ductwork once. It was close..

 

[Aileron]

Ive seen it. More common then you think ,at least in commercial / industrial.

Had a boiler that was a new install, had a service call every monday that it was locked out ,then it hit me. It was under construction and they kept the mechanical room door open during the week. So you would arrive and restart and all was fine. On the weekend the general locked the place up shutting the door to the room. It had a fresh air drop but was not big enough and if you install a grill you have to deduct 25% from the opening from what it is open. I kicked the door closed and let it run and it dropped out. Same boiler , they put the outlet of the 12"dia. stack within 4 ft of the fresh air intake for the air handler. Got up on the roof on a cold morning and watched the air handler pulling in the exhaust. It got raised.

Tuning a burner on a large firetube boiler , i almost had it dialed in then within a blink of a eye the tune was out the door. Co spiked thru the roof. Found out the plant was cycling their exhaust fans on and off to clear the building from smoke and fumes from their production.
Its unreal when tuning burners how many fresh air opening are clogged up and do not get cleaned. Some places use fans to pull air in , had a powerhouse you couldnt get to the fans, I stuck a magnehic across the door and pulled the rolldown shut. Building went negative becuase those intake fans didnt run.

 

[rerod]

Ive experienced it in the U of I chiller plant and Currier hall. Neither had gas appliances except for cloths driers in the dorm, but they kept adding exhaust fans but no supply fans. The chiller plant was so bad, it almost took a crowbar to pry any door open to get in, and the dorm basement smelled like sewer gasses. They added a balanced exhaust/supply system to the chiller plant while I worked there, but the 100 year old dorm was a total sh!t show. Glad I never have to go back!