Cracked heat X ????

[chuckcrj]

Curiousity getting the better of me..... how many of you use a CO meter (calibrated before entry to home) while doing clean and checks?

All the top techs!

I carry a CO meter on every call to alert me if I walk into a dangerous space.

I do a combustion analysis on all gas or oil burning equipment I work on.

[JonesHVAC-R]

All the top techs!

I carry a CO meter on every call to alert me if I walk into a dangerous space.

I do a combustion analysis on all gas or oil burning equipment I work on.

Lol, I agree there! Leads to my next question...

How many of you when entering home and get a reading anywhere from 1-6ppm recommend replacing the furnace right there? (assuming the CO is coming from the furnace during operation)

[BigBacardi]

lol...loaded question

but yes... i do carry my co detector into every job.....responses from homeowners vary, but most are impressed

[chuckcrj]

Lol, I agree there! Leads to my next question...

How many of you when entering home and get a reading anywhere from 1-6ppm recommend replacing the furnace right there? (assuming the CO is coming from the furnace during operation)

If the furnace is spilling CO and causing house levels anywhere above zero then yes new is the first choice. Usually there is a repair option as well if the HO can't afford new. (unless the HX is cracked, which is almost never the cause of CO getting into the home)

[Mickandmousemechanical]

A rusted heat exchanger is not a failure if there is no "visible crack or hole".

What type of heat exchanger is it? When you open up the supply duct and look at it are the seams folded and welded. Because those particular H/E are tanks and seem to last. With a bore scope through the burner section they look cracked but indeed they are not.

I agree no visible crack or hole = No red tag

[martyinlincoln]

Curiousity getting the better of me..... how many of you use a CO meter (calibrated before entry to home) while doing clean and checks?

Got a perfect example of why that's important today. Lennox G20 that another company replaced the heat exchanger last year. It had the typical stress mark and rust line along the back but passed water test. Cleaned the burners,crossovers,pilot assembly and flame sensor then put it back together to get some flue gas readings. Stuck the probe in the flue and had 4.2% O2 and over 9000 ppm of CO,I know should have pulled the probe out way before that to save the sensor. Gas valve was cranked all the way in and reading 7.2", backing it out didn't change the pressure. Installed a new gas valve and made a new sheet metal flange that the bone heads left out. CO 14ppm with 7.2 O2 after fixes.

[JonesHVAC-R]

Got a perfect example of why that's important today. Lennox G20 that another company replaced the heat exchanger last year. It had the typical stress mark and rust line along the back but passed water test. Cleaned the burners,crossovers,pilot assembly and flame sensor then put it back together to get some flue gas readings. Stuck the probe in the flue and had 4.2% O2 and over 9000 ppm of CO,I know should have pulled the probe out way before that to save the sensor. Gas valve was cranked all the way in and reading 7.2", backing it out didn't change the pressure. Installed a new gas valve and made a new sheet metal flange that the bone heads left out. CO 14ppm with 7.2 O2 after fixes.

7.2"!! I had a tech once turn one down to 2" while I was away... I got back and asked why so low and he replied that is where it needed to be in order for the burners not to snuff out... Not quite sure what the hell he was thinking there... I told him to come with me and it turned out they weren't snuffing at all but they cutting out from the rollout sensor. Old Bryant 80% rooftop unit with just about everything rusting... gave them the option of repair or new unit, they took the new unit

[JonesHVAC-R]

If the furnace is spilling CO and causing house levels anywhere above zero then yes new is the first choice. Usually there is a repair option as well if the HO can't afford new. (unless the HX is cracked, which is almost never the cause of CO getting into the home)

Are you saying that if a heat exchanger is cracked that CO will not get into the home?

[bigtime]

Has anyone anywhere found a home with carbon monoxide in the living space, and the cause was a small crack in the furnace heat exchanger? If so Id like to hear the details.

On any residential co problem, Id put my money on a vent problem. Spend more time inspecting vents...

[bigtime]

Another question. Has anyone anywhere found a home with co in the living space and it was casued by a gas pack?

[chuckcrj]

Are you saying that if a heat exchanger is cracked that CO will not get into the home?

If there is CO getting into the home, the crack is the least likely culprit. In fact it is right up there with winning the lottery, just about impossible.

[JonesHVAC-R]

Has anyone anywhere found a home with carbon monoxide in the living space, and the cause was a small crack in the furnace heat exchanger? If so Id like to hear the details.

On any residential co problem, Id put my money on a vent problem. Spend more time inspecting vents...

Actually, out of 4 calls this month I had 3 homes reading anywhere from 3-9ppm and 1 reading above 20ppm(shut furnace down before it got any higher). Out of those 4 two had cracked HX's. The one with 20ppm+ was carbon build up in the HX and the exhaust, customer upgraded anyway. The last one had a bad inducer assembly.

[chuckcrj]

Actually, out of 4 calls this month I had 3 homes reading anywhere from 3-9ppm and 1 reading above 20ppm(shut furnace down before it got any higher). Out of those 4 two had cracked HX's. The one with 20ppm+ was carbon build up in the HX and the exhaust, customer upgraded anyway. The last one had a bad inducer assembly.

What were the CO levels in the flue?

Carbon buildup? That is just a symptom of a larger problem.