Did My YJ Gauge Manometer Fail Me?

hvaclover

Join Date: May 2007
Location: in a state of confusion
Posts: 3,903


Did my YJ gauge manometer fail me?
I had a Tech IV furnace over gas and shoot flames into the furnace vestibule after i installed a new igniter. i installed the furnace back in 96 and the HO insisted nothing had been done since, yeah right.

The Smart Valve manifold press was 5"wc by my analog manometer.
I recalibrated it to 3.5" and refired it. 3 ot of 5 retries flames shot out of the burners. Each time it overfired the manometer was steady on 3.5" and the sound of gas going into the burners was much louder than normal.

The same thing happened at 3". The needle did not deflect up durning any of the back fires.

I finally got the burners to operate normally at 1.75". Before I forget supply press was 7"wc constant.

I installed a new 90% furnace and hauled the old one away.


Today I did an autopsy onthe old Consolidated furnace.

Here's the result:

Inducer:-90" wc---normal operation.

Heat ex: No cracks or separation at collector box.

No blockages in heat exchanger.

Cross lighters: Clean

Burner Orifices: Clean

Position of igniter: Installed with pilot positioned correctly for pilot light off of main burners.

That leaves the smart valve regulator. But what i don't get is why there was no increase in gas press when the flames shot out of the furnace.

I doubled checked my manometer against another one tha I know is accurate and it agreed.

What gives?

flashheatingand

Maybe some type of blockage in the flue piping?

hvaclover

pulled the flue off..sameo sameo