CO Help

Jim Davis_3

No, there not really funny because they are happening, but to read what the media, utilities, fire departments etc say, is ridiculous.

Mass. - Neighbor saves family when he sees carbon monoxide leaking from their house. Need to hire this guy, he is good!!

TX. - 200 people evacuated from hotel, several needed medical attention. According to fire department spokeswoman this is vary rare at hotels. Bull-poopy!! #1 most dangerous building!!!

ARK. - 25 people needed treatment because forklift had CO leak. Must have been a hole in the exhaust pipe. Duhhh!!

N.D. Police are investigating the possibility of CO poisoning. Lady and kids found in SUV in garage with the engine running and a hose running from the exhaust into the vehicle. Hmmm, lets see what else in the garage might have made them sick???

There were multiple stories in the past 7 days where people have been poisoned by their furnace or water heater. Don't need to check for CO in the summer!!

Don't care if it is a damn A/C call, keep your analyzers running and keep checking all fuel burning appliances that could operate before Fall!!!

Wild Rover

CO Help

I recieved a call tonight from a customer from this past winter regarding CO level in their house. I relocated their existing boiler and waterheater in Feburary and they have been operating with no problems until today. They are moving into the house now that the remodel is complete and today said that CO detectors were going off. They called the Fire dept, Gas company etc.

Gas company employee thought that MAYBE the flue on the water heater needs more pitch. Unless sombody else has altered or worked on the flue piping this is not the case.
They did not shut the gas off only turning the Water heater down to vacation mode(???).

I will be going there tommorow to look and see for myself. I believe they just recently turned on the new central air due to the 90+ temps here in MA. Could these new conditions somehow effect this situation.

And just to shed some light on the entire situation they called last week to have a small job done before they move in and i explained to them that i had not been paid for the completed work and didnt feel comfortable doing any further work until being paid.
Thanks in advance

Timco

I would test all equip I ever touched with a good analyzer and bring your own belt clip CO tester. Their unit could be bad or old. If there is a CO issue that should be dealt with regardless of outstanding balance as it is their lives at stake, then lean on them for payment when all is certified OK.

Tim

Wild Rover

I agree

Thats for the reply. I agree with everything you have said.

Mitch_6

Problem could be anything

90F outside hurts draft if they just turned on the water heater it may have taken time to warm things up.

AC or whole house fan can make negative draft.

Moving truck could have had its motor running, lots of co cases do not involve heating equipment.

New paint or other chemicals can fool a co alarm.

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Plumdog_2

drywall sanding

and contruction dust can clog up the screen on a FVIR water heater, or the heat exchanger on the boiler, the result could be elevated CO.

Jim Davis_3

The reason the boiler or water heater is making CO is secondary to the actual problem which is something is not venting properly. Even if either was running properly as far as CO is concerned if they are not venting CO will develop over time at high levels. A draft test can be use to verify if the flues are functional and then if anything in the house is interferring. Turn on the water heater and see if there is draft with nothing else running. If there is, then turn on the A/C & see if this has an affect. Do the same with the boiler. If there is no draft when the water heater is running by itself then there may be excessive house leakage using the flue for make-up air.

CO problems can be very intermittent but the systems of problems are always detectable.

Wild Rover

The Results

I went out to the house in question today with my combustion analyzer and got normal results. The central air was turned on for the 1st time on Saturday and i'm assuming that there was some type of false reading from the dust, etc..

I did get a reading of 14ppm in the attic when the ac unit was running which was the highest reading in the entire house.

Thanks for the replies

Mark Hunt_4

Curious

What are "normal" results?

Mark H

jp_2

I am no expert here, but

I'd be concerned about 14ppm in the attic.

sounds like theres a vent/chimney leak thats filling the attic. attic should be venting fairly good this time of year, doesn't sound good.

Dale

CO

If the air handler for the AC is in the basement you could have a blower inlet leak that could reverse the heater flue. When you go back let the exhaust fans run 15 min. to check for backdraft.

Mitch_6

I typically get 0 - 2 ppm with my Testo personal alarm

or TSI analizer in ambient space.

Did you check the flue gas in the equipment.

Did you check draft with all house openings closed and fans running.

Mitch S.

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Wild Rover

Attic still an issue

I went back 1st thing this morning and did check the flue gases. Boiler about 16 ppm and the water heater 6 ppm. I ran the WH alone and then added the Boiler. I went up to the 2nd floor and got an elevated reading of about 6 ppm ambient CO at the attic pull down stairs. I went up into the attic and the reading went up to 17 ppm with the boiler and WH running.

There is a new B-Vent chimney(permit and inspection)that was installed before I arrived on the job that i am starting to believe is the problem.

I am also getting 0-2 ppm ambient in the rest of the house. Where do I go from here? The house is empty and will not be occupied until this is resolved. They have been living in their old house during construction.

The return air duct for the central air is located about 7' from the pull down stairs.

Mitch_6

If 16 is your max at the boiler and 6 at the water heater

17 although close does not add up. Run the water heater alone or at least try to keep all shut down until you get a zero or lower number. If you find the only appliance running is 6ppm and the attic is significantly higher than the source has to be other.

You could have an off gas issue still. You could have a negative pressure issue and pulling in from ridge and soffit vents.


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jp_2

not quite right

PPM is read for a certain volume of air. so things normally do not add up straight. all depends on the venting, fresh air, air movement, size of rooms appliance is dumping into etc...

Is the B vent high enough off the roof surface? inspected or not. a quick test would be to add another section.

Jim Davis_3

You can't get 17ppm of CO from something only making 16ppm and you don't add 6ppm and get 22.

Put a draft guage in the flue of the water heater and watch the draft. Then turn on the Air handler and see if the draft changes. If it does you do have duct leakage problems. I guessing the boiler isn't usually running at the same time the A/C is running although if the boiler and A/C are on separate thermostats this could happen.

You have to be absolutely positive the CO readings in both appliances do not rise the least amount after 2-3 minutes.

You said you installed a new flue. Is there any chance you have an old chimney that not being used near the new flue or a fireplace chimney? It is very possible for the flue gases to go out one chimney and right back down one next to it. Seen this on many multi-tile chimneys, especially in the summer with the A/C running. Again you could have some type of re-inflitration from the roof.

Dale

thinking more

The added info now makes me think the attic is not adequately vented and made negative by the AC running. I think the b vent isn't tight, the height of the vent, as suggested by the other post, could be raised at a small cost. good luck

Bob Harper

CO concentration

Jim Wrote:"You can't get 17ppm of CO from something only making 16ppm and you don't add 6ppm and get 22."

Huh? Jim if the space is not ventilatiing, you can get high CO as it concentrates. He quoted the 16 & 6 as flue gas measurements while the 17 was an ambient reading in the attic. The ambient CO is a function of CO production rate coupled with the house ventilation rate. If that attic is not vented but there is exfiltration from the thermal envelope of the home into the attic, sure it can concentrate much higher.

The questions remain:
are the appliances properly installed?
are the appliances properly operating?
are there any external influences on their operation such as negative pressure from mechanical ventilation systems?
is the venting designed and sized properly?
is the venting properly installed and undamaged?
are there any external forces that could be causing a recirculation of gases back into the attic and home?
Is there spillage of CO2 into a confined, unventilated CAZ?
Had the water heater been on standby with the pilot priming the flue or was this a cold start?


I recommend a full inspection of these items along with complete combustion analysis and worst case depressurization testing. You may want to scope the B-vent liner as part of your inspection.
Bob

Jim Davis_3

WoW! CO does not concentrate any higher than what is being produced. If you put 16ppm and 6ppm in a room you end up with 11ppm concentration. CO can only be diluted not concentrated. If you poor 50% coffee & 50% cream into a container all day the concentration will not change. But if you add 25% coffee and 75% cream the percent of coffee will be diluted.

Mitch_6

Are we not talking about air free in our measurement

if so. Ambient co 2ppm, equipment auto zero (i.e. my tsi analizer) infiltration 16ppm air free, reading is 18ppm. Since the equipment thinks it is starting at zero but the sample is really 16ppm.

No auto zero (i.e. my testo personal alarm) 16ppm.

this would be assuming total infiltration in an area not located by the equipment. If the combuston air was recirculated flue gas we would get a rising co. In this case we are talking about an attic remote to equipment.

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Jim Davis_3

If you auto zero in 2ppm the analyzer won't read 1ppm until it gets to 3ppm. Therefore reading would only be 14ppm. If it auto zeroed in 16ppm it would read 0ppm with 16ppm present. Analyzer can only subtract, never add.

Mitch_6

Thanks for the correction



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jp_2

16 ppm, 17ppm its all the same..

you can not guarantee the last digit in most digital device to be perfectly accurate. therefore you must except that the 16 ppm and 17ppm is the same reading within devices ability to read accurately.

read the specification of your analyzer.

Mitch_6

I agree in fact

the readings change in the flue piping in different places and I have never seen to analyzers side by side read exactly the same.

I think we are however splitting hairs. A proper analysis needs to be done. It has been stated that the AC was on and it was unlikely the boiler was running so we should be working with a co of 6ppm for the initial call.

What set the alarms off and what level are they set to go off at are they low level or UL alarms.

Mitch S.


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Bob Harper

Jim you speak of the CO level as being a constant. However, with spillage, CO, CO2, and nitrogen are spilling into the CAZ. As one volume of gas enters a space, pre-existing gas is displaced since air does not compress in a house. As the old air exfiltrates the room and is replaced with the spilling gases, the concentration rises. You don't spill 16 molecules of CO and that's it. Count the molecules of CO after 1 second of spillage then again in 1 minute then i hour. Now, how many molecules of CO are in the room? Since room air was displaced, the concentration is now higher. This is the same thing that happens in a combustion chamber. From the moment gas flows from the burner orifice into the burner, the gas concentration in the combustion chamber rises. Once it reaches the flammability limits, it can ignite. If ignition fails and gas continues to flow, the concentration rises well above the upper flammability limit and cannot ignite. CO does the same thing. If there is a single bolus release of CO into an under ventilated space, eventually, the concentration will drop to zero. Similarly, if a small dose of CO is released into a home, such as from an oven, the room CO level will spike near the stove. As it dilutes out, the level around the room and house will rise to a low level then drop to zero as it equilibrates and dilutes out.
Sorry Jim but I still disagree.
Bob

jp_2

close but no cigar

jim is 99% correct, the 1% could happen with help(in a lab) but you will not ever see it in a house.

first off, if you dump CO in a room, the measured concentrations will drop. once the room has completely filled with the vent gases the rooms PPM value will equal whats coming out of the vent. now if you fill a room with X amounts of red golf balls and Y amounts green golf balls, they will always be in the same proportions, same the PPM value,

analyzers do no count as you are suggesting. they "sample" volumes of 'air' and tell you the concentration of that volume. not the number of molecules in that sample.

Jim Davis_3

Bob, you have the right idea, just the wrong results. As CO and other flue gases start displacing air in a room combsution air is affected. Because the CO2 displaces O2 less air will get to the burner and it will then make more than 16ppm. Someone ask me one if you had a 90% furnace that got 100% of its combustion air from outside but vented 100% into the space what is the highest the CO level could get in the room if it was making 30ppm. The answer is 30ppm. You add 30ppm or molecules of CO but you are also adding 999,970ppm or molecules of air. The concentration remains the same.

I doubt unvented appliances could ever be allowed if the concentration of CO could get higher than what it is producing. That is probably why less people get killed by unvented appliances than vented because they are designed not to vent.

jp_2

are you talking about

CO thats entering a room separate from the intake to the burner or in the same room? that changes the conversation a bit.

Jim Davis_3

If you have a 90% furnace and you pipe the intake to outside air for 100% outside air for combustion. You vent the furnace 100% into the house. If the furnace is making 30ppm in the flue gas, that is the highest the house can get until the furnace starts making more than 30ppm.

jp_2

yep i agree

nm

Bob Harper

ventfree example

What we are talking about is a furnace backdrafting, which has the same net result as a ventfree appliance. With a ventfree, you do not have a ducted source of MUA nor do you have a vent exhausting gases out of the CAZ. The same molecules remain in the CAZ unless there is ventilation of the CAZ, either passive or mechanical. So, if you have a relatively tight, under ventilated room, the ventfree will begin consuming the room O2. The theory is, once the room air O2 level reaches about 18.5%, the flame speed of the pilot slows to the point it has advance past the thermocouple of the ODS pilot causing it to shut down. If the ODS were to fail and the burner continued, it would burn until the room air reached 16% where the flame would snuff out for lack of O2. Up to that point, however, you are making CO using the existing air in the room. Therefore, you million part sample is being chemically changed from N2,O2, and trace gases to CO2 and CO. As Jim noted, the CO2, being heavier than air, will settle to the floor displacing oxygen, leading to incomplete combustion and a higher production rate of CO. Since the room is under ventilated, the CO remains in the room. If you are not ventilating room but making more CO, the concentration must rise. Your million part sample size remains one million but it contains less O2 which has been replaced by more and more CO2 and CO even with the burner still making the same amt. of CO. As the O2 drops and you get more incomplete combustion, of course the burner will produce even higher CO in an insidious cycle. BTW, per ANSI Z21.11.2b, ventfree are allowed to produce 200 ppm air free CO. Since there is no vent, the 'air free' sample is taken immediately above the burners.

Healthy discussion. Friendly disagreement exercises the brain and is good for all. In this case, we are all winners simply by discussing the possibilities.
Bob

jp_2

one VERY wrong statement

""""As Jim noted, the CO2, being heavier than air, will settle to the floor displacing oxygen""""

sorry this is a totally incorrect statement. the weight difference between CO, CO2, N2, O2 are of no real consequence. if this were true, we would all be dead from CO2 world wide production, global warming would kill us before it changed the climate.

if you read up on kinetic energy forces of gases and compare with the gravitation force it will be clear. all these gases mix in equal proportions.

you are right, in a closed system the CO will rise once the room has saturated with CO, but some of that CO will then burn, converting to CO2 thud reducing CO production.

Mad Dog_2

I have yet to see a truly false CO reading...........

you just haven't found the source yet. Listen to Jim and Mark...these fellas ARE the foremost CO experts in the USA!!! mAD dOG

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Jim Davis_3

CO2 has a molecular weight of 44. O2 has a molecular weight of 32. CO2 falls to the floor like a rock. Over time there is diffusion and mixing but it is a slow process. Being fortunate to have had CO2 monitoring equipment I have been able to test the actual CO2 buildup. Having watched a rooftop slowly run out of air on a flat roof because of the way package unit vent on the same side as the burner inlet. The way you can tell that it is continuos buildup and displacement versus recirculation just watch how the deterioation increases. Just standing and talking with a CO2 monitor on the floor next to me I watch the CO2 at the floor almost double in just a few minutes while there was no change at eye level.

When it comes to CO it is just the opposite. Have measured from floor to ceiling in homes, office buildings, warehouses etc. The CO was always 2 to 5 times greater at the ceiling than the floor. Again over time with no new gasses being added there will be mixing.

Doubt fire extinguishers would be very effective if CO2 didn't displace O2 fairly easily versus mixing with it.

JP I have read many articles that have said similar things as you have posted, but really don't believe the people that wrote then did much testing. Many others have witnessed the reality that actually occurs in the field. Not the first time people have tried to mislead us with bad science and it won't be the last.

Bob Harper

CO2 displaces O2

Just to agree with Jim I have tested using both a combustion analyzer and a dedicated CO2 meter that measures ppm. You may not get much CO spillage, esp. if a unit is burning very cleanly. However, if you have spillage, you Will get CO2.

You can test for it using an ordinary combustion analyzer by measuring the room O2 near the floor. If CO2 is spilling and being ventilated out, the room O2 will begin dropping from 20.9% as the CO2 displaces it. If you then re-measure flue gases, you will start to see the change. With my CO2 meter, I can read an ambient level of 400+ppm then watch it quickly rise to several thousand ppm when there is spillage. Remember, we are talking about the Combustion Appliance Zone here and not the globe. Outdoors, you have plenty of wind and convection to move CO2 around. You also have green plants eating it to make glucose and O2.
Bob

jp_2

bad science or missunderstand what you read?

first off how much does a molecule of CO weigh?

if you tell me exactly what you have read, maybe I can explain.

Jim Davis_3

Molecular weight of C(carbon)= 12
Molecular weight of O(oxygen)= 16
" " " CO = 28

Remember CO is always hot when it comes out and goes up. Because the warmest air in the room is at the ceiling in tends to hang around their the most.

Although CO2 is also hot when it is spilling, it rapidly cools and drops like a rock before it ever has a change to go up.

And as Bob has said and I concur because I use the same demo in the field. That is placing your analyzer probe at the floor in front of an appliance that is spilling you can actually watch the O2 reading go down from displacement of the CO2. Once you see and measure it, what others might speculate is no longer fact.

jp_2

corrrect and incorrect

a mole of CO weighs 28grams. a molecule, a single CO floating around, weighs 600 trillion, trillion times less. 6 followed by 23 zeros.

a weigh thats rather hard to comprehend.

I would guess what you have read deals with a static conditions, all gases at same temperature. to describe what is going on mathematical in a system with greatly varying temperature is very complex. you are looking at a air pump pumping hot gases around the room, totally different.

can't see why CO2 would rapidly cool and the CO wouldn't?

but you are right things take time to stabilize.

I have done calculations proofing the weigh between CO and CO2 is of no consequence. you have told me this is true also in the post above.

jp_2

analyzer readings

I do not doubt what you and jim Davis have measured in the field, but your conclusions are a bit questionable.

if CO2 displaced O2 has you suggest, wouldn't ventfree heaters blanket the floor wit CO2 killing the dog and crawling kids. plus wouldn't the basement fill up?

when you read CO2 levels increasing around the base of the water heater, what about CO levels?

are there absolutely no CO2 levels increasing around the ceiling? CO2 cooling from 400F to room temp in less than seconds really does not seem feasible, unless you are measuring temps from 400F down to room temp along the sides of the hot water tank.

jim, you made no comment about the true weigh of CO? wondering what you were thinking about my statements?

takes a lot of simultaneous measurements to support your claims, you need to account for all gases leaving the opening in the vent?

Unknown

Jim I have experienced

exactly the same thing many times. Seeing an accumulation of CO2 caused by spillage from the draft hood or in case with gas ovens venting into the room and accumulating toward the floor and contaminating the O2 causing progressivley high levels of CO. I have also noted that room temperature has an affect on this many times. Rooms bringing very cold air directly from outdoors (non mechanically) and getting down below 45 degrees causes both CO2 and CO to tend to seem to get a higher specific gravity and disappate much slower.

Bob Sweet

Dont really want

to seem like a rookie, but it is what is is! Could you define MUA, CAZ and ODS. Just trying to cognitavely follow the conversation.
Thanks

Edit: After re-reading post I got the ODS. Please define MUA and CAZ.

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