A place to post unusual things that are not WTF, just unusual (to you).
I had not see a condensate trap like this:
The text on the label says “warning non-conventional venting”:
If the trap overflows, water comes out the little up pointed clear plastic tube.
The system was draining normally via gravity to the outside.
The manual says “check at least monthly”. Pretty sure once a decade is more realistic…
Condensing NG furnace condensate filter. Nothing unusual in this type of condensate disposal.
Filter serves as a filtration neutralizing device for the what can be highly acidic condensate created during the NG combustion process in gas-fired, high-efficiency appliances.
Not a trap per-say… It’s a filter.
Look at date/age of filter. Examine flues, flue material, if any in masonry chammies. It will eat away at masonry walls. Leaks of any kind.
Do CO sampling.
The furnace clearance looks suspect.
Not seen that either.
Robert, I did not say it was unusual.
I simply said it was the first time I’d seen that setup.
The condensate neutralizer and the trap were separate. The condensate neutralizer, which no doubt is no longer operable, is behind the pictured pipe. If there’s a filter I did not observe it, nor was a filter mentioned in the manual.
The manual suggested checking the condensate neutralizer monthly, which was basically impossible. Nobody has ever checked it… The driveway it dumped out onto had moss but no damage. I’m positive nobody has every checked that, or replaced the neutralizing chemicals.
The trap section is what I found unusual. Again, that’s separate from the neutralizer.
A place to post unusual things that are not WTF, just unusual.
Sorry Bryce. I misread your post.
As for a trap, I do not see any.
The manual appears to call it a trap:
It looks more like a drip leg to me. Perhaps others know more about this style of condensate management system.
I have not seen that exact set up. But it appears to be a variation of the common high efficiency furnace flue condensation trap.
I concur. Trap would have an airgap, clean out provision and dispersal tube running to a floor drain or pumped up to a DWV.
Decommissioned fuse box found in ceiling of a historic century home.
Partially decommissioned fuse box found in the same home. This one was on the wall in a hallway. 
Very nice woodwork and trim!
The difference is that “drip leg” which is called a “trap” on the manual.
Your photo has the drain at the bottom of the leg.
My example the drain opening is a good 6" above the lowest point.
That 6" is what seemed unusual. Is that just filled with stagnant water and flue slime 
?
Did you catch the asbestos paper and fused neutrals?
I admire the workmanship (yes, “man” at the time) of the knob & tube of the era. What survives is heads and shoulders above today’s average.
Ooh, I did not really notice that paper until you said something. Will add it to the report. Thanks Bryce!
Yup. Not sure why that trap is so deep or what criteria is being met. But the basics are pretty universal.
Bryce, can you post the Model and Serial numbers please.
My mistake. I beg your pardon.
Non-conventional trap.
From what I can make out, from the technical diagram from your original thread post, 3rd image down, still leaves no clearance for neutralizer observation and replacement and condensate dispersal point and method.
The Lennox Pulse furnace had a specified similar setup.
Did the pulse specify a cleanout interval? The one I saw the bottom cap could not be removed… e.g. a permanent repository of whatever.
