Y does bad Heat x cause co?

ken D

I found 500 ppm from a flue and knew right away it was a bad nat gas heat exchanger. Looked a few seconds and found a crack.

Why does CO result from a bad Heat x? Ins/outs

Is it the supply breathing air from the blower entering the flue (high pressure goes to low pressure--always) and diluting the combustion process and lowering the flue gas temps--leaving unburned fuel creating co? I don't know if I read this, someone told me this, or I read it in Beckets guide to oil heat and applied it to gas?

Is it true? No, why then anybody?

Mark Hunt

You got it.


Mark H

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Rudy

Just curious

Why did you suspect the 500 ppm was due to a crack?

tim smith

co from bad heat x

I would say it it the impingment on the flame causing air to not be entrained in the combustion, this in turn causes the high CO in your flue readings.

David_5

Good question

If CO was low with blower off then went up after blower starts then that points to a crack. If CO starts high with blower off then something else may be the cause.

David

Ken D.

ken D.

Please be advised that this is a different ken D. than myself. I use capital K in Ken D.

Ken D.

CO

The reason for the high CO is that the extraneous air from the cracked heat exchanger causes the unit not to vent properly. This results in recirculation and reburning of the flue gasses that increases CO2, thusly increasing CO. Ken D. with a capital K.

Ken D.

Different ken D.

Be advised that this is a different ken D. than myself. I use a capital K in Ken D. Thank you.

Ken D.

Different ken D.

Be advised that this is a different ken D. than myself. I use a capital K in Ken D. Thank you.

Rudy

My experience....

> The reason for the high CO is that the extraneous

> air from the cracked heat exchanger causes the

> unit not to vent properly. This results in

> recirculation and reburning of the flue gasses

> that increases CO2, thusly increasing CO. Ken D.

> with a capital K.

Rudy

My experience....

Is that when the CO reading increases when the blower comes on, I also smell burning hair from my eye lashes and beard (fortunately, my hairline has receded sufficiently to keep it away from errant flames).

To me, a more sensitive indication of a crack is a change in the O2 reading when the blower energizes.

I've even seen situations where the CO reading goes down whe the blower comes on (and a crack is present).

I was just curious what the CO reading was before and after the blower came on....

Jim Davis_3

Leaky blower doors and ductwork can cause the same problem. Actually O2, CO and Draft need to be checked simultaneously to determine which problem is the actual cause.

Dale

CO reason

The reason for CO is change from designed. Natural gas has a VERY narrow range of primary/secondary air where it will burn in a furnace with very low CO. This is because the flame speed of natural gas is not a bell shaped curve but more of a spike on the oxygen (in the air) line. So, anything that changes conditions from what was designed changes flame characteristics and will produce more CO. The furnace was not designed with a crack,cracks or holes. If you can take the heat exchanger out of your old furnace and I'll bet (based on your 500ppm) you find more cracks ect from the one you saw. Spray the outside with WD 40 and look inside of the old one out at the curb.