Combustion Test

Dave Jahnke

This is the first time that I will be using a combustion analyser on a condensing boiler w/ a modulating gas valve. What steps do I need to take in order to get a proper reading? Flow? Return Temp?

rudy_2

You probably should contact the manufacturer and see what readings it is designed and engineered for.

Just a wild guess, you probably should see a 7% to 9% O2 reading at high fire - low fire will probably be higher, but again that's just a guess. When you contact the manufacturer let me know what you find out - or get in touch with me and I'd be happy to talk with them - I'm in the process of getting a list together with the different manufacturer's suggested readings.

jim sokolovic

Combustion testing a condensing boiler

I am not familiar with the boiler design that you are going to test - but if you are looking to get an efficiency, you won't be able to factor in the condensation produced, so you will probably get 89 % steady-state at best. This test is done at 120 degree water in / 140 degree water out - which is tough to hold steady in the field. Is there a way to manually override the modulation, and keep the burner at max. and min. inputs for your readings? If it is modulating at will, your readings will change. If it has a premix burner, usually the CO2 is the same or lower at min. input than at max. input. The CO and flue temp. should be lower, and the efficiency should be higher, at min. input. Hope this helps, and let us know what is recommended by the manufacturer.