Using Testo 320 Combustion Analyzer to Test For Proper Flue Gases If You Ain’t Checking Your Guessin

Heating tuneup on a ComfortMaker 80% gas furnace - only 1 year old. CO over 50ppm. We adjusted and brought it down to 17ppm.

[@thermcontrol9976]

Sir, you have reduced the manifold pressure without putting a manometer on the gas valve. Is it the correct procedure?

[@cesarhernandez3275]

That’s exactly what I was saying is I’m watching this video he has no idea what the gas pressure is now 🤷🏽‍♂️

[@forzamilan07]

Curious what the gas pressure is and what do you use to cover the hole you drilled

[@Keegeth]

do you use the same co limit for oil too? probably

[@johnszymanski548]

Would love to see what the manifold pressure was before you adjusted

[@Brendan_Clancy]

I’d love to see where it was when he was done adjusting. Yeah, CO of 17ppm is great, but not if the outlet gas pressure was, like, 2.9inWC 🤷🏼‍♂️

[@thermcontrol9976]

@@Brendan_Clancy , but the manufacture manual says 3.5" WC. Don't you think it is under firing?

[@jonathantorres4689]

Yea

[@KnownAsSimo]

There’s a manufacture range for gas pressure, and without hooking a manometer up you have no idea what you just adjusted pressure to. If you’re below range that Is also not correct procedure

[@benjamintimmins1656]

So you prob went from 3.5 to 3.9 to get less CO and more efficiency right?

[@wd8557]

No 3.9 is over firing. If the gas valve is rated at 3.5 then that is what it must be set at.

[@nathanhurst5155]

3.5 is nominal and gas valves have a range. Normally 3.2-3.8 is the acceptable range

[@benjamintimmins1656]

@@wd8557 I think that's why your supposed to use a combustion analyzer. It let's you reduce CO and increase efficiency. 3.5 is usually just what it's supposed to be set at. But going up wont hurt it it will only decrease CO. That's why people adjust gas pressure on gas appliances...

[@wd8557]

@@benjamintimmins1656 You use a manometer to check gas pressure period. Only time I have used a c/o analyzer is for furnace tune up, or for the required inspection of a rental property. I had a valve that fired at 4.9 wc and the furnace shut down on hi limit. It sounded like a jet taking off on start up. If I could only have one tool out of the two it would be the manometer.

[@larryh2161]

Probably not since the exhaust temp dropped almost 5 degrees

[@JamesBrown-db9pk]

thats lamw new furn should not b 50ppm dont turn down valv look b4 u start messin with the gas your gaessin thats y i cant wacth u any more

[@wd8557]

The gas valve was over firing loser.