CountryPlans Forum

General => General Forum => Topic started by: OlJarhead on June 26, 2013, 02:48:50 PM

Title: CO Problem?
Post by: OlJarhead on June 26, 2013, 02:48:50 PM
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).

QuoteLow 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.
(https://i998.photobucket.com/albums/af102/emcvay/Cabin/IMG_0367364x640_zpsae1be15a.jpg)

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!  d* d* d*
Title: Re: CO2 Problem?
Post by: OlJarhead on June 26, 2013, 03:28:22 PM
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?
Title: Re: CO2 Problem?
Post by: rick91351 on June 26, 2013, 03:34:55 PM
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.   
Title: Re: CO2 Problem?
Post by: OlJarhead on June 26, 2013, 03:42:31 PM
Quote from: rick91351 on June 26, 2013, 03:34:55 PM
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!!!
Title: Re: CO2 Problem?
Post by: BAdams on June 26, 2013, 04:03:34 PM
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.  ???
Title: Re: CO2 Problem?
Post by: OlJarhead on June 26, 2013, 05:17:43 PM
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.

Title: Re: CO2 Problem?
Post by: kenhill on June 26, 2013, 08:04:19 PM
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.
Title: Re: CO2 Problem?
Post by: OlJarhead on June 26, 2013, 08:25:22 PM
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!
Title: Re: CO2 Problem?
Post by: UK4X4 on June 26, 2013, 10:18:20 PM
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 !

Title: Re: CO2 Problem?
Post by: OlJarhead on June 26, 2013, 10:29:45 PM
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.
Title: Re: CO2 Problem?
Post by: OlJarhead on June 27, 2013, 11:07:51 AM
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).
Title: Re: CO2 Problem?
Post by: UK4X4 on June 27, 2013, 11:11:56 AM
does the water heater have a pilot light ? that stays on ?
Title: Re: CO2 Problem?
Post by: OlJarhead on June 27, 2013, 11:34:12 AM
Quote from: UK4X4 on June 27, 2013, 11:11:56 AM
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.
Title: Re: CO2 Problem?
Post by: SouthernTier on June 27, 2013, 11:39:02 AM
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 (http://countryplans.com/smf/index.php?topic=10487.msg134049#msg134049), 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
Title: Re: CO2 Problem?
Post by: OlJarhead on June 27, 2013, 11:45:06 AM
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).

Title: Re: CO Problem?
Post by: kenhill on June 27, 2013, 11:48:46 AM
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.
Title: Re: CO Problem?
Post by: OlJarhead on June 27, 2013, 12:12:54 PM
Quote from: kenhill on June 27, 2013, 11:48:46 AM
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.
Title: Re: CO Problem?
Post by: OlJarhead on June 27, 2013, 12:28:32 PM
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??  ???
Title: Re: CO Problem?
Post by: SouthernTier on June 27, 2013, 12:44:45 PM
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:

QuoteG2407.6.1 (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.
Title: Re: CO Problem?
Post by: OlJarhead on June 27, 2013, 01:58:11 PM
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.
Title: Re: CO Problem?
Post by: MountainDon on June 28, 2013, 07:28:40 PM
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.
Title: Re: CO Problem?
Post by: Jeff922 on June 29, 2013, 08:14:58 AM
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. 
Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 09:04:17 AM
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
Title: Re: CO Problem?
Post by: Jeff922 on June 29, 2013, 10:16:45 AM
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.
Title: Re: CO Problem?
Post by: OlJarhead on June 29, 2013, 10:53:34 AM
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.
Title: Re: CO Problem?
Post by: OlJarhead on June 29, 2013, 11:02:08 AM
Quote- Fresh air intake: The room in which the heater is located must have an air inlet not
less than .75 square feet (roughly 9" x 12" or larger).

That is from Marey.

QuotePRECAUTIONS:
1. The water heater must be installed in a well-ventilated area. An exhaust pipe of
double walled steel for Class 3 appliances (located at most home improvement
stores in the water heater section) must be installed to discharge the exhaust from
the flame. During operation, the water heater consumes a lot of oxygen, so the
exhaust pipe and outlet hole must be properly installed. Refer to exhaust pipe
section for details.
- Failure to properly install the room intake and exhaust pipe will cause
oxygen depletion in the area around the water heater, which can cause
incomplete combustion. Carbon monoxide poisoning, death and serious
accidents can occur due to incomplete combustion. ALL USERS OF GAS
APPLIANCES OF ANY TYPE SHOULD EMPLOY THE USE OF A CARBON
MONOXIDE DETECTOR.
(https://i998.photobucket.com/albums/af102/emcvay/Cabin/Hotwater_zps1424f030.jpg)

So, they spelled it out, I ignored it (not completely).

The problem I had with this is that they wanted me to have a 9x12 inch opening into the outside world INSIDE my cabin I've worked so warn hard to make warm and cozy.  I installed the hot water heater on the outside of the cabin but didn't want to put such a large vent to the outside world as it completely defeats the purpose of installing inside all together -- let's face it, below freezing weather with 9x12 inlet means frozen pipes and a useless heater in the winter.

Where am I going wrong here?

Perhaps I can install the trickle vents provided I use at least two of them?
Title: Re: CO Problem?
Post by: Jeff922 on June 29, 2013, 11:09:57 AM
Trickle Vent is intriguing.  Seems like it would do the trick.
Title: Re: CO Problem?
Post by: OlJarhead on June 29, 2013, 12:00:34 PM
Quote from: Jeff922 on June 29, 2013, 11:09:57 AM
Trickle Vent is intriguing.  Seems like it would do the trick.

Only thing is, and I just did the calcs, it's 1.77CFM per vent.  Theoretically that would be 3.54 CFM with two of them but is that really enough for an instant on hot water heater?  That I don't know.
Title: Re: CO Problem?
Post by: OlJarhead on June 29, 2013, 12:02:36 PM
http://www.dr-fix-it.com/hvacduct.html
This shows a 9x12 vent flowing 1750cfm which seems an awful lot for this heater considering I've read that woodstoves draw about 350cfm.
Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 02:12:32 PM
OJH.... after installing the stove fresh air system I would most likely call it good for now and see what happens. If the detector detects any CO in the future I'd try to figure out why and then see what to do. I'd do that before installing a passive or an active air exchanger. That is as long as there are no other issues such as high humidity and condensation on windows.


The rule for sizing rooms vs gas appliance use is 50 cu ft of room air per thousand BTU. This link (http://nvhousing.state.nv.us/weatherization/Appendix%20F%20-%20CombAir.pdf) has info. If the interior space is too small then exterior venting is required. It's Nevada specific and is based on the UMC (another one of those codes that help us figure things out; there is generally a code for just about anythng we can shake a stick at  :)  )  and though old the numbers are the same for NM so probably a good guide for all.
Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 02:20:06 PM
Further info on gas appliances and combustion air
http://staff.jccc.edu/jbennett/current/Fall%20Classes/Heating/COMBUST.htm


My water heater install directions notes:  1 square inch of free vent area per 4000 BTU/hour rating for vertical ducts and 1 sq in per 2000 BTU/hr for horizontal ducts. Same info on the new furnace.


I now recall that was another factor involved with the decision to not get an on demand whole house water heater several years ago. Not only did we need new gas piping to cover the higher volume for the burner but the venting needed changing too (heater in center of house meant a fair amount of disruption.
Title: Re: CO Problem?
Post by: Carla_M on June 29, 2013, 04:56:59 PM
Quote from: OlJarhead on June 29, 2013, 12:00:34 PM
Only thing is, and I just did the calcs, it's 1.77CFM per vent.  Theoretically that would be 3.54 CFM with two of them but is that really enough for an instant on hot water heater?  That I don't know.

If one was an inlet and the other an exit it would only be 1.77 wouldn't it?  You need 4, two pair for 3.54.
Title: Re: CO Problem?
Post by: OlJarhead on June 29, 2013, 05:12:54 PM
Quote from: Carla_M on June 29, 2013, 04:56:59 PM
If one was an inlet and the other an exit it would only be 1.77 wouldn't it?  You need 4, two pair for 3.54.

I was thinking that when the heater was lit it would draw from both since they are not restricted.  Thus two can be 3.54cfm intake as long as that much is being drawn out through the heater stack.
Title: Re: CO Problem?
Post by: OlJarhead on June 29, 2013, 05:13:30 PM
Quote from: MountainDon on June 29, 2013, 02:12:32 PM
OJH.... after installing the stove fresh air system I would most likely call it good for now and see what happens. If the detector detects any CO in the future I'd try to figure out why and then see what to do. I'd do that before installing a passive or an active air exchanger. That is as long as there are no other issues such as high humidity and condensation on windows.


The rule for sizing rooms vs gas appliance use is 50 cu ft of room air per thousand BTU. This link (http://nvhousing.state.nv.us/weatherization/Appendix%20F%20-%20CombAir.pdf) has info. If the interior space is too small then exterior venting is required. It's Nevada specific and is based on the UMC (another one of those codes that help us figure things out; there is generally a code for just about anythng we can shake a stick at  :)  )  and though old the numbers are the same for NM so probably a good guide for all.

The thing is, the woodstove wasn't actually being used when the alarm went off.  Only the cook stove and the heater.
Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 05:47:54 PM
 ???  well then something was not burning efficiently and making a good amount of CO. Reason would have to be either an appliance not "tuned" for the altitude or insufficient air supply if everything was properly tuned for the altitude. That is assuming no restrictions to the burner or chimney flue.  The issue I had was spider webs in the flue. That was the same thing that nearly killed our neighbors a few years back. The burner)s) had the proper size orifice for the altitude, but there was a restriction. You would think the flame of the pilot or burner would be enough to burn spider webs away fully, but it can be enough of a problem to snuff you.

You mentioned being pink or red cheeked or faced. That is a very bad sign. More often seen in the deceased than the living IIRC. CO is used to make meat appear more red to the consumer. Hope you figure out the cause and the cure. Everything running well should not produce CO like that.
Title: Re: CO Problem?
Post by: Jeff922 on June 29, 2013, 07:14:16 PM
Also OJH, are you sure the proper orifices are installed for LP?  Which is to say, are you sure the proper conversions were done?   In addition to that, what about the gas pressure?  I know tankless units require the pressure to be in a certain range or they just won't work properly.  You could have your gas company come out and do a manometer reading at the regulator and at the heater itself.  I think this is a fairly common problem.
Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 07:48:36 PM
pressure check may be a good idea. OJH's cabin is rather remote so not likely a serviceman is a cheap deal. There are LP gas manometers, simple ones with a tube, that can be foind on amazon for maybe $30 or so.

Title: Re: CO Problem?
Post by: OlJarhead on June 29, 2013, 07:52:19 PM
The heater is specifically LP so that shouldn't be an issue but I don't know if running it at 3200 feet makes a difference  ???

No way to get someone to come out without spending a fortune! lol

I'm using an old BBQ regulator which is supposed to be in the right range,.
Title: Re: CO Problem?
Post by: Jeff922 on June 29, 2013, 08:06:21 PM
I think Don has the right idea.  Pick up a manometer and just eliminate that variable (you can always ebay it when you're done).
Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 09:07:08 PM
Quoteold BBQ regulator

Ah-ha!!  Well maybe.

A grill regulator is a simple one stage regulator. A typical propane installation from a large ground mount tank uses a set of two regulators; a high pressure and a ow pressure. The high pressure reg drops the tank pressure to about 10 psi. It is mounted at the tank. The low pressure regulator is mounted at the house or close to it. The low pressure reg drops the pressure to 11 inches of water.

Single stage regs are not as precise as separate high and low stage regs. Appliances such as ranges, furnaces and water heaters require more precise pressure and supply regulation than a BBQ grill or small space heater. The single stage regulator may be the source of the problem. A good two stage regulator such as found for RV use can be used in place of the separate high and low pressure regulators (as long as the cabin/home is not being inspected and as long as the propane comes in portable cylinders, 20 to 100 lbs.

That's a maybe, not a guaranteed solution, but one that holds great promise.

Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 09:11:17 PM
Good regulators are quite dependable. One reason a regular home propane system uses two individual regulators is for safety. If a regulator diaphram fails \the regulator will pass the inlet side pressure through to the output side. With a system of two separate regulators if the low pressure regulator fails it will pass 10 psi; more than what is needed but not overly dangerous. Appliances will usually blow themselves out. If a single stage regulator diaphram fails the full tank pressure is passed to the inside of the bldg.  I am not certain what happens if the high pressure reg diaphram fails in a two reg system (hi-lo)
Title: Re: CO Problem?
Post by: OlJarhead on June 29, 2013, 09:49:58 PM
Good info, thanks Don!

We have two 20 gallon tanks (100lb) that we want to use and planned on getting a regulator to fit them (not the same ACME style as the BBQ tank) so that might help.  I have been meaning to head to a propane place to get that done.  Seems like it's time.

Also, on a side note, the stove has a built in regulator but still requires the .5psi (I believe that's right) regulator on the tank.
Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 10:04:05 PM
stove/range regulators want to see 11 inches water column coming in. They refine that to the precise pressure required for reliable operation.

We have used the RV two stage regulators with only one problem in many many years. Starting with the RV for 20+ years and then in the cabin. They are less cash than the "real" system of hi and lo regs. I've never been worried about them, though I do have a spare for just in case on some cold winter day.  I bought mine online through http://www.pplmotorhomes.com/parts/lp-gas/changeover-lp-regulator.htm

The spare is mounted with all hoses and piping using a union fitting for quick detach and swapping. Hope to never need it but...  (years ago we had one fail on the RV at a very inconvenient time and location ... once burned, twice shy...) 
Title: Re: CO Problem?
Post by: MountainDon on June 29, 2013, 10:30:51 PM
I forgot to mention there may also be a small chance that the regulator might not be able to deliver the required volume of propane the appliances were asking for. Especially if the weather was cold and the tanks close to empty or smaller than 100 pounds.
Title: Re: CO Problem?
Post by: Jeff922 on June 30, 2013, 07:58:06 AM
I'm probably stating the obvious here but for the proper volume you have to have your lines sized properly too.  I ran 3/4" black-pipe directly to my tankless heater as required by the manufacturer (Takagi TKjr-2 which is a small one).