Secondary Heat exchanger test

raptorman · September 22, 2009, 05:39:08 AM

I was in touch with carrier tech support regarding how to properly check the secondary heat exchanger.
I was told to do a flue gas test and if the c02 was over 8.5% for nat gas (10.5% lpg) the secondary was defective!

Has anyone else heard of this and does this apply to all secondary heat exchangers??

Thanks

Admin · September 22, 2009, 12:44:21 PM

Yeah I use those figures as well. The best test is still a visual one, if you remove the blower you can use a mirror or scope to check the top side for cracks. Usually you'll have pressure switch lockouts or flame roll out with a good crack. ICP uses plastic headers that crack on the top side.

raptorman · September 24, 2009, 05:49:57 PM

I would like if people that read this give me feedback.
this could help us all.

acefurnacefixer · February 04, 2010, 09:47:19 AM

Its a hell of alot easier to just pull the blower and look at it, or if you have a see-snake u can look down through the high limit hole.........

I dont know about up in canaDA, but here in the states we are finding that about 99% of these units are failing.

Hgye · February 04, 2010, 05:46:42 PM

How old are the units?

Admin · February 04, 2010, 08:55:45 PM

I posted a few stories regarding the Carrier heat exchanger problems in our General News section - Here

The lawyer who won the class action suit has some info posted - Here

Our province, Ontario, was also a part of the lawsuit, regarding Carrier secondary heat exchangers.

I also find alot of failure on the primary heat exchangers, on both mid and high efficiency models. Just remove the primary limit and run your index finger over the golf ball sized indent. Usually you will see or feel the crack.

Visit the Private Heat Exchanger for more examples.

acefurnacefixer · February 05, 2010, 07:23:43 AM

Quote from: Hgye on February 04, 2010, 05:46:42 PM
How old are the units?

any were from 12 to 20 years old

keeptheheatup · February 18, 2010, 01:36:32 PM

I came across the same problem a week ago . I did a flue analysis and had to pull the flue probe out because the co was to high. Upon further inspection found the secondary to look just like acefurnacefixer pic.

Admin · December 09, 2010, 04:39:14 PM

Download the Carrier Service Bulletin SMB 09-0022 - Here

612Rob · February 03, 2011, 11:16:03 AM

I've been told that there is a possibility you will not get an elevated CO reading on a cracked H/E but you will get the elevated CO2 readings.

Admin · February 06, 2011, 09:38:07 AM

It's true, but like I said in your other post, analyzing flue gas at the termination is useless. It has to be done before the gasses enter the venting.

Only when a crack causes flame impingement or incomplete combustion will you get high CO readings.