CO Problem?

[OlJarhead]

OK so many of you here are building, or have built, small cabins with wood stoves and propane cook stoves etc (maybe a fridge or instant on hot water too) but I wonder how many realize they may be experiencing CO poisoning without knowing it?

Up until this past winter I wasn't too worried about the subject because our cabin wasn't fully insulated and there were many ways air could get into the cabin (or out of).  It was more of a problem of heating and losing said heat then anything else however last winter after sealing off most of the cabin finally and insulating all but a small portion I felt that we might be in danger of CO poisoning one night.  We had gone to bed with the wood stove burning brightly and had left a window cracked 'just in case' but in the middle of the night I awoke to a strange dizzy feeling with a headache and a flushed face.  I immediately got up and opened two windows, began to feel better and went back to sleep (after stoking the fire).

I'd planned on installing a fresh air intake for the stove but just hadn't done it yet and admonished myself for it.

The winter passed without incident (or so I thought anyway) and I installed an instant on hot water heater (propane) with a 'vent' in the bathroom into the enclosure for the heater.  My thinking was that I wanted the warmth of the cabin in the winter to keep the heater from freezing in case we wanted to make use of it.  I'd read the instructions and noted the part about venting the room it was in but felt I could just leave a window open or something and get a CO monitor to be on the safe side.

Fast forward to this past weekend. 

CO monitor installed and regular use of the cook stove and hot water revealed no issue until, for some reason, the CO alarm went off Monday morning!  I had eaten breakfast, had my morning coffee and used the hot water.  Thinking something was wrong I checked the alarm but realized my face felt flushed and I felt somewhat 'odd'.  I opened a window but the alarm took some time to clear (not until I opened doors too and move some air around and had my son open a window in the loft).

Low levels can cause shortness of breath, mild nausea, and mild headaches, and may have longer term effects on your health. Since many of these symptoms are similar to those of the flu, food poisoning, or other illnesses, you may not think that CO poisoning could be the cause.

After the event we discussed the issue and determined it was likely something effecting us before and we just never realized it.

SO now a question for the experts out there:

In a small cabin like ours (14x24) with a propane cook stove w/oven, an instant on hot water heater and a wood-stove (which we now have the fresh air intake for) what is the best way to provide fresh air and prevent CO poisoning without letting in a lot of cold air (or bugs)?

My current thinking is to install an air inlet at the bottom of our hot water heater 'closet' which is on the outside of the cabin.


It could be installed at the bottom of this enclosure which I think would help prevent heat loss since hot air rises.  I was also thinking that it could also have a sliding or swinging door with door seal like a trap door, which could be closed when not in use or opened once the cabin is warm and we want to use the hot water.

I was also thinking maybe I should install a fresh air vent in the floor near the wood stove (like a register) for the same reason (or maybe only one there).  This floor vent may have the added benefit of providing heat to the crawl space once it's enclosed to help keep pipes from freezing.

All ideas welcome.
Much thanks
Erik


PS.  GET A CO MONITOR / ALARM! 

[OlJarhead]

http://freshairvent.ca/
Could this be the solution to my problem? 

Seems like a simple solution with a filter built in.

of course I still plan to install the fresh air intake for the stove but I'm wondering if this wouldn't be a good thing to install also?

[rick91351]

Locally they had a GI back from deployment staying at his girl friends apt.  He died do to CO2 from a poorly vented hot water heater.  Then come to find out there had been numerous complaints and calls in this apartment complex as I guess many were vented improperly. 

I post this just to say you can not be to careful!  CO2 does kill.  Lets all take a lesson and stay safe.   

[OlJarhead]

Locally they had a GI back from deployment staying at his girl friends apt.  He died do to CO2 from a poorly vented hot water heater.  Then come to find out there had been numerous complaints and calls in this apartment complex as I guess many were vented improperly. 

I post this just to say you can not be to careful!  CO2 does kill.  Lets all take a lesson and stay safe.   

It amazes me how I/we didn't really worry about this and how much it now appears we were exposed to it.  I am a believer in the alarms now!!!

[BAdams]

I strongly agree. CO is a very dangerous gas. Anybody with natural gas, propane or wood appliances should have a CO monitor! I use the CO monitor/smoke alarm combination units.

You are very lucky that you woke up...CO is odorless and colorless.

I wish I knew the answer to your question. 

[OlJarhead]

I am starting to thin that the trickle vent might do the trick and could be installed in the cabin in two places.

1.  Behind woodstove
2.  Opposite wall in the loft

Still waiting to hear back from them but this seems like a good idea and will likely keep the cabin smelling fresh too.

[kenhill]

Looks like your Instant water heater is already vented outside.  I have not heard of a wood stove creating CO.  That would leave the stove and any propane lights or propane Fridge.  I am surprised that a stove would create that much CO to cause a problem.  We burn a propane range, 30,000 BTU Radiant heater and 9 propane mantles in the winter and have never had the CO detector go off.

[OlJarhead]

The Hot Water heater has a vent stack for exhaust gasses that goes outside of course and the wood stove was not burning however I think you are forgetting something

Combustion requires oxygen.

While the stove runs it burns Oxygen which leaves less in the room if the room is well sealed and of course, the hot water heater does the same.  Sure it exhausts emissions however it draws oxygen from the atmosphere in the room thereby reducing it unless there is a way to replenish it.  This is why people leave windows open with wood stoves and why states have put fresh air intakes into their regs for wood stove installations.

In our case I suspect my attempts to seal the cabin from drafts has been VERY successful and as such we now have a situation in which anything using oxygen depletes the cabin of same and since it's a small cabin there isn't as much to draw from.  I was reading a wood stove can draw as much as 350cfm when burning!  So fresh air intakes are clearly needed (or an open window that more then just a crack.

Not sure how much the propane stove uses or the hot water heater (off hand) but it's clearly more then I thought!

[UK4X4]

The vent from the water heater looks to be right next to a window which looks to be not completely sealed flashed/ finished
-- extend up and above

But as you were sleeping and not making hot water the stove sounds like the culprit as it was on at the time

If the stove is overdamped and wood is still smoldering but has no direct escape, the stove will leak from somewhere- ash pan etc etc

With the fire on and in its night setting move the c02 detector towards it and see if it activates

Try a colored smoke bomb----not sure where you'd get one mind you and see where the leaks are

We had a scare last winter in our trailer -with the generator running and wind circulating the exhaust gasses under the trailer

The bedroom alram went off first and then the living area one.

Glad I invested in them ! and am able to participate in life !

[OlJarhead]

Actually the stove wasn't on Sunday night.  Only thing we had was the propane stove in the morning to make coffee then oatmeal and the hot water heater afterwards.

I agree the stack is short and needs to be extended but it hasn't created the problem previously -- perhaps the windows were open.

[OlJarhead]

No one?

I'm liking the Tickle vents and think they might be a key element to eliminating the problem as well as increasing the vent stack to above the window (and probably the roof).

[UK4X4]

does the water heater have a pilot light ? that stays on ?

[OlJarhead]

does the water heater have a pilot light ? that stays on ?

Nope.  The system uses a battery ignites that kicks on when the water pressure changes from turning on the tap.  There are safety's built in so it won't light without water in the system that's running at the specified pressure etc.

The time the stove was burning nothing else was on (that was in the winter) and from what I read this is typical because wood stoves can draw so much air from the room they are in and we're a small cabin after all.

[SouthernTier]

Two things:

One, as noted above, what kills you is Carbon Monoxide (CO), not Carbon Dioxide (CO₂).  The anecdotes to the unfortunate deaths are probably related to CO, not CO₂.  As far as I know, there are no CO₂ detectors, just CO detectors.

Combustion overwhelmingly produces CO₂ (and water).  It doesn't have to produce any CO.  However, in practice, some amounts of CO are also produced, especially if parts of the combustion area don't receive enough oxygen (i.e. inefficient combustion).  That's why it is important to monitor for CO.

Which brings me to "Two":  You can't necessarily solve your problems just by making sure that everything you are burning inside the house is burned efficiently.  This may make the CO problem go away, but it will cause CO₂ to build up, and oxygen to deplete.  In most cases, you'd never get to the levels where this becomes a problem (normal air is 21% oxygen, in my line of work, we check to make sure we never have less than 19.5% oxygen - that's where we set alarms).  But still, there is a lot in the codes about providing combustion air.

I realize you aren't a huge fan of codes, but these provide some good solutions to your problem.  I am not an expert on the codes, but here are some links that may be helpful:

http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_24_sec005.htm
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_appb_par001.htm
http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_17_sec001.htm

Also, CO monitors are required by code:

http://publicecodes.cyberregs.com/icod/irc/2012/icod_irc_2012_3_sec015.htm

[OlJarhead]

I don't have any problem with codes  I only have an issue with forced compliance.  I'm more of a voluntary compliance type person.

For example, while no one that I know of within miles of me owns a code compliant wood stove I do.  Same for much of my cabin. 

The wood stove has the correct (and code compliant) chimney however the issue as I understand it is oxygen depletion when the stove is running since I have not yet installed the fresh air intake (which I have and intend to install).  However, the propane cook stove has no vent provision (perhaps a hood is code?) and the hot water heater instructions say there must be an air inlet vent (not yet installed).

[kenhill]

It looks like the water heater is outside too.  Oxygen depletion should not set off a CO detector. So the only combusion that would create CO is the stove which has electronic ignition.  Perhaps the dector is bad or the battery is down.

[OlJarhead]

It looks like the water heater is outside too.  Oxygen depletion should not set off a CO detector. So the only combusion that would create CO is the stove which has electronic ignition.  Perhaps the dector is bad or the battery is down.

Brand new detector -- and the hot water heater isn't really outside.  The 'door' is open to show it but it's actually attached to the side of the cabin and insulated with a large vent to provide warm air from inside the bathroom.

[OlJarhead]

Hmmmm it looks like I don't really understand the issue.

So oxygen depletion isn't a problem?  To me it seems that if you burn the O then you'll have to have a way to replace it -- and without that you get less O so more CO -- perhaps I'm totally wrong there.

I'll look at the chimney and push that up ASAP.

This does confuse me though because I've always understood that the fresh air intake for wood stoves was regulated for just this reason -- same reason people open windows when burning a wood stove.

What am I missing here?? 

[SouthernTier]

I don't think you are missing anything, just confusing two separate issues.

The first issue is that appliances that use combustion do often produce CO (especially if they don't burn efficiently), which can kill.  Appliances like this need to be vented outside.  I think propane stoves and pilot lights are pretty efficient since they are open flames with no obstructions for oxygen to get there, so the burning reaction is pretty much only C₃H₈ + 5 O₂ -> 3 CO₂ + 4 H₂O.  I.e. little to no CO production.  That's why these don't necessarily have to be directly vented outside.

But as this shows, you are indeed using up oxygen.  That is the second issue.  You need to replace this consumed oxygen.  Code section G2407.6 (see first link in my earlier post) indicates how to do this:

G2407.6.1 (304.6.1) Two-permanent-openings method.
Two permanent openings, one commencing within 12 inches (305 mm) of the top and one commencing within 12 inches (305 mm) of the bottom of the enclosure, shall be provided. The openings shall communicate directly, or by ducts, with the outdoors or spaces that freely communicate with the outdoors.

Where directly communicating with the outdoors, or where communicating with the outdoors through vertical ducts, each opening shall have a minimum free area of 1 square inch per 4,000 Btu/h (550 mm2/kW) of total input rating of all appliances in the enclosure [see Figures G2407.6.1(1) and G2407.6.1(2)].

Where communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of not less than 1 square inch per 2,000 Btu/h (1,100 mm2/kW) of total input rating of all appliances in the enclosure [see Figure G2407.6.1(3)].

G2407.6.2 (304.6.2) One-permanent-opening method.
One permanent opening, commencing within 12 inches (305 mm) of the top of the enclosure, shall be provided. The appliance shall have clearances of at least 1 inch (25 mm) from the sides and back and 6 inches (152 mm) from the front of the appliance. The opening shall directly communicate with the outdoors or through a vertical or horizontal duct to the outdoors, or spaces that freely communicate with the outdoors (see Figure G2407.6.2) and shall have a minimum free area of 1 square inch per 3,000 Btu/h (734 mm2/kW) of the total input rating of all appliances located in the enclosure and not less than the sum of the areas of all vent connectors in the space.

[OlJarhead]

FIGURE G2407.6.1(3) [304.6.1(3)] ALL AIR FROM OUTDOORS (see Section G2407.6.1)
G2407.6.2 (304.6.2) One-permanent-opening method.
One permanent opening, commencing within 12 inches (305 mm) of the top of the enclosure, shall be provided. The appliance shall have clearances of at least 1 inch (25 mm) from the sides and back and 6 inches (152 mm) from the front of the appliance. The opening shall directly communicate with the outdoors or through a vertical or horizontal duct to the outdoors, or spaces that freely communicate with the outdoors (see Figure G2407.6.2) and shall have a minimum free area of 1 square inch per 3,000 Btu/h (734 mm2/kW) of the total input rating of all appliances located in the enclosure and not less than the sum of the areas of all vent connectors in the space.



The graphic with this looks kinda like what I'm thinking with the trickle vents but I'll have to check how they rate with the above.

[MountainDon]

1. I seriously doubt the wood stove has any direct connection to any CO levels. Indirectly though a wood burner that draws combustion air from the building interior can cause back drafts from any gaseous fuel burning apparatus. This is one reason a gas water heater is required to be isolated from the habitable space.

2. I don't recall your altitude, but fuel gas burning appliances need adjustments or new small jets or orifices as the altitude increases. Our range was rejetted and adjusted for the 8800 feet, as was the direct vent wall space heater and the water heater. The range is the only item that does not have a fresh air feed or a direct to exterior vent.

Incorrect air/fuel mix, or in other words, using the standard setup at an altitude higher than the basic setup was spec'd for, will result in too rich a mix which leads to incomplete combustion of the fuel gas and subsequently production of CO.

We have two CO monitors/alarms as of this spring. When the cabin was first built we had one. CO sensors age and are recommended to be periodicaly replaced. The first one came with info that said to replace every 5 years. The new one ststaed 7 years. The old one will be tossed when the batteries get low.

The detector in our cabin has only signaled an alarm once. A couple years ago on the first day we relit te propane fridge it went off. I shut down and cleaned the flue on the fridge. Itr was good after that. Now I do a quick clean with the brushes I have whenever relighting after more than a day or two shut down. It is easy once you learn how.

At home the detectors have never "alarmed". They test good just no CO in the house. That is with a gas range and all other gas fueled devices installed according to instructions. I think when one steps outside the manufacturers installation parameters the chances of running into issues increases.

3. I think the chances of CO problems are much greater than running into a low O₂ problem. I base that on my own blood oxygen readings that I took regularly over a period of time two years ago. There was no meaningful, certainly no dangerous fall in the reading during extended periods of being inside with windows closed, range being used for baking and cooking. This was a winter weekend and the weather caused us to be inside more than outside. Also minimal opening of windows and doors.

Keep in mind that our blood will latch onto a CO molecule with great tenacity. The blood will want to hang on to the CO even after the CO source is gone. Our hemoglobin just loves CO better then O₂. If CO in blood reaches too high a level even pure oxygen can not reverse the situation.

[Jeff922]

I'm following this thread with much interest as I've also experience some CO issues in my Victoria's.  I've had my CO detectors alarm twice.  First off, I sealed my house up super tight (6mil poly vapor barrier with taped seams on the walls, all sheathing seams without blocking were caulked, Tyvek housewrap with taped seams, etc.) - this house is very "air-tight".  When I poured my foundation slab I planned on a fresh air intake below the stove, but when I looked at the logistics of it (cost of ductwork, keeping critters out, keeping external vent above snowline, how to "throttle" it, etc), I said to myself "why am I going through all this trouble when the window three feet from the stove addresses all of these issues?".  So being a minimalist, simple-is-better kinda guy, that is what I chose to do.  My tankless hot water heater, which is my other heat source in conjunction with the woodstove, is direct-vented and therefore not part of the equation.  I do have a gas stove and a gas dryer however.  When the CO detectors alarmed, the dryer, stove and woodstove were all going and I had forgotten to crack the window by the woodstove.  I had figured that the woodstove was consuming a lot of oxygen and therefore,without a fresh air source, the combination of the the dryer and gas stove were running inefficiently and producing (and poorly venting) CO.  Am I on the right track with my thinking here?  I installed my own gas line plumbing and I'm quite certain everything is sized correctly.  I'm also pretty sure the regulator is providing enough water column because I haven't experienced any trouble with the tankless unit.  So I'm a bit perplexed.  Maybe I need to "tune" my gas stove again and make sure it's burning efficiently?  I installed the natural gas-to-propane conversion kits in the dryer and stove myself so they should be burning correctly.  My wife said the clothes in the dryer dry much quicker with a window open so that reinforces my hypothesis a bit.  I just really don't know.  I pretty much have a window cracked all the time in the winter to keep a flow of fresh air into the house.  Sooooo, why the heck did I build it so tight to begin with?    At very least I have some control as I can "throttle" my fresh air intake with a window as needed. 

[MountainDon]

You are on the right track IMO Jeff. The wood stove lowers the oxygen level enough to cause inefficient burning with gas appliances. That leads to CO production. Got space for a air exchanger? Extra tight buildings often need them. Needing to open a window to heat safely just somehow irks me. I was lucky in that installing the fresh air intake was simple and direct through the wall behind the stove. Used a vent hood and screened it. There are vent hoods made with the flsp orientated for inlet air

[Jeff922]

I know what you mean Don.  I kinda hate feeling that cool air coming in the cracked window when I put so much effort into building an efficient house.  I know of some old-timer builders out there who insist that a home should "breath", which is partially true, but is used somewhat as an excuse to build things "kinda leaky".  Perhaps the old dogs are right but this idea irks me as well.  I'm generally a technology skeptic and having to put in an air exchanger with moving parts, fans, sensors, running power to it, etc. kinda bugs me too.  I guess I just need to figure out what irks me more.   I wonder how the heating efficiency would  increase with an air exchange (and how it translates into dollars) as opposed to the window cracked?  I don't know.  If I ever sell this house (and I don't plan on it), I would probably put in an air exchanger just because it seems like the "right thing to do" as most people simply don't understand the complexities of a home's ecosystem.

[OlJarhead]

http://freshairvent.ca/?page_id=179

THis leads me back to these trickle filters.

Would not they work once the woodstove has the fresh air intake installed (I'm installing one like Don did but without the fan)?

In my case the hot water heater wasn't designed for a direct vent but the installation does say to have an outside air inlet in the room it is installed.  I, perhaps foolishly, thought I could get away with it because of limited use etc.

I'll have to check to see if they have a recommendation on CFM of the outside air inlet.