Steam boiler combustion test question...

Steamhead (in transit)

have adjustable air shutters, try opening them. This will change the ratio of primary air (drawn in thru the shutters) to secondary air (drawn in around the burners). The increased primary air will shorten the flame length and reduce impingement, which can cause CO.

Also, where are you measuring your draft- before or after the draft hoods? If the draft is that high before the draft hoods, reducing it slightly may help too.

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Timco

So I test these 3 units AFTER a really good cleaning of the HX's. Really sooted, and nasty, but clean. Checked gas press, 3.5 WC. My tester seems fine, but after stack reaches temp for a few minutes, the CO numbers shoot WAY up and WAY down to more acceptable range. Could this be the tester? Draft on all 3 units is -0.02 WC, and pretty strong up in the main vent. All 3 units begin as follows, and the middle unit stays here : Ex air 37.5, Stack 414*, O2 6.2%, CO2 8.3%, CO 53ppm, COAF 75ppm. Then the lft jumps to a max of Ex air 26.5, stack 388*, O2 4.8%, CO2 9.1%, CO 263ppm, COAF 341ppm....and the right boiler even got to: Ex air 30.9%, stack 388*, O2 5.4%, CO2 8.8%, CO 744 ppm, COAF 1003ppm!!!

Any ideas here? Units run very well except for the numbers, and do not roll out anymore...they look & sound great. Just need to get those numbers in line!

Thanks, Tim

Robert O'Brien

My

Wohler analyzer does the same thing.The CO will stay at 18PPM (or whatever)for 30 seconds or so and then "count up" to 3000 and then come back at stop at the original reading for another 30 seconds and then repeat the same as long as the pump is running

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Timco

Checking draft just outside the boiler. The shutters are all fully open. We went over checking orifices in class, but that was years ago...might that be the problem?

Tim

Steamhead (in transit)

Couldn't hurt to check that

get the manufacturer's specs and compare them to what's there.

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