# Naked Science Forum

## Non Life Sciences => Technology => Topic started by: peppercorn on 02/10/2009 18:02:30

Title: How much free oxygen does the exhaust gas from my gas boiler contain?
Post by: peppercorn on 02/10/2009 18:02:30

It's an average non-condensing boiler, probably under 10 years old.

After it has burnt the gas in normal operation how much O2 is left in the exhaust stream.

Any random estimates greatly appreciated!!
Title: How much free oxygen does the exhaust gas from my gas boiler contain?
Post by: peppercorn on 02/10/2009 20:01:39
I found this:
Calculating Air Supply (http://www.energysolutionscenter.org/boilerburner/Eff_Improve/Operations/Air_Supply.asp)
Quote
In general, the following formulas have been developed to determine the amount of air required for any boiler room with a package firetube boiler firing gas or fuel oil.

1. Combustion Air = HP* x 8 CFM/HP =
2. Ventilation Air = HP* x 2 CFM/HP =
3. Total Air Required = HP* x 10 CFM/HP =

Because this page is talking about a boiler room sized boiler, I'm not sure if ventilation air is for the room or the boiler.
If it's actually what's drawn into the boiler air intake then it implies that 80% of the oxygen is burnt.

Personally, I think this is too high.
Title: Re: How much free oxygen does the exhaust gas from my gas boiler contain?
Post by: CycleGuy on 04/08/2015 06:50:16
Old thread, I know, but information like this doesn't go out of style.

The boilers at work run with 3.7% exhaust oxygen. These aren't really "boilers" in the traditional sense, they're giant water heaters, more or less... they heat water at about 575 GPM from the 200 degree F return temperature to anywhere upwards of 320 degrees F.

The discharge water temperature varies because our boilers are designed to maintain a constant return water temperature.