Cracked Air Exch?

[James H. Bushart]

HVAC specialist question:

During fire up and prior to blower, flue gases measured 9.0 Oxygen, and 75.6 XAir. After blower, O2 went up to 9.6 and XAir to 85.0.

Is this enough of a change to indicate a cracked air exchange? Is there an acceptable range published somewhere?

[Brian A. MacNeish]

Originally Posted by jbushart

HVAC specialist question:

During fire up and prior to blower, flue gases measured 9.0 Oxygen, and 75.6 XAir. After blower, O2 went up to 9.6 and XAir to 85.0.

Is this enough of a change to indicate a cracked air exchange? Is there an acceptable range published somewhere?

Definitely communication from the pressurized house air side of the heat exchanger to the combustion gas side. May be cracked exchanger or bad gasket, if any installed. IMO, should be called.

[Gary Reecher]

Bacharach in their literature calls out any change in oxygen +/- .5 percent when blower comes on may indicate a heat exchanger leak.

[Doug Edwards]

Im just curious as to where you are taking these flue gas readings?

Additionally, here are some videos of heat exchanger cracks. YouTube...who knew.

http://www.youtube.com/watch?v=8e9hP...eature=related

http://www.youtube.com/watch?v=xIKvP...eature=related

[Gary Reecher]

Originally Posted by dedwards

Im just curious as to where you are taking these flue gas readings?

Additionally, here are some videos of heat exchanger cracks. YouTube...who knew.

http://www.youtube.com/watch?v=8e9hP...eature=related

http://www.youtube.com/watch?v=xIKvP...eature=related

The undiluted flue gases. Vent pipe on 80% and 90% furnaces. Up through draft diverter into each cell exhaust.

[Darin Redding]

I'm looking for a recommendation on a combustion gas detector. What devices/brands do you use?

[ldapkus]

Originally Posted by dredding

I'm looking for a recommendation on a combustion gas detector. What devices/brands do you use?

I like the Bacharach 2 225

[James H. Bushart]

This is what I use.

[Darin Redding]

Spendy little devices. Wow. And you use them primarily to check o2 and co2 levels at the registers?

I guess my new concern is not discovering a cracked heat exchanger.

[Brian E. Kelly]

Originally Posted by dredding

I'm looking for a recommendation on a combustion gas detector. What devices/brands do you use?

Don't get one.....

[ldapkus]

Originally Posted by dredding

Spendy little devices. Wow. And you use them primarily to check o2 and co2 levels at the registers?

I guess my new concern is not discovering a cracked heat exchanger.

A good days' energy audits will pay for the device. I have 3 on hand.