Thread: Furnace vent type

Is this an acceptable vent type for venting of the furnace. I don't think it is, but just wanted a second opinion. Thanks in advance for all replies.

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It's difficult to see from here.

Sorry about that. Picture is now posted.

Depends on appliance and manufacturer instructions. It does not look like it would be approved.

Might be something like Simpson DuraConnect:



Dura-Connect 4" x 24" Bendable Length - Hart's Hearth & Patio

hard to tell from that picture.

I believe that looks like a Z-flex gas appliance connector product.

If that is a Cat I furnace it might be considered appropriate, however if that is either Z-flex singlewall or Z-flex insul-vent, it is not properly installed.

Attached two pdf files (hopefully) on the two Z-flex connectors mentioned.

If the furnace is not Cat. I it might be a special gas vent connector, however not properly installed.

Note damage as well.

It does not have to be a "B" Vent, it can be a single wall vent connector. Although I would recommend a B-Vent "T" at the bottom so the vent connector can be installed into the side of the "T" instead of the bottom, also to replace the vent connector and clean it up, looks pretty shoddy workmanship.

Also note the non-standard BS trap on the AC. Even without the obvious water stains on the side of the furnace, I would suspect that drain to back up and leak out of the pan. Write it up, of course include the lack of air gap.

Originally Posted by Markus Keller

Also note the non-standard BS trap on the AC.

That is a "running trap", and they are not allowed.

A "running trap" is one in which the inlet and the outlet are at the same level compared to each other (even if the trap is at an angle, which - of course - it is not allowed to be).

Every manufacturer that I have seen requires *at least* a 2" trap seal between the trap weir and the bottom of the trap, and *at least* 2" from the trap weir to the inlet from the air hander unit.

See first drawing for MINIMUM trap requirements, I have seen some which required 3" where the 2" is shown, and some which required 5" where the 2" is shown - but I have never seen less than the 2" shown.

The second drawing shows a running trap, and it even has a circle with a diagonal line through it showing that it is not to be used. That 'V' trap is a running trap.

Write it up, of course include the lack of air gap.

I must not be seeing what you are seeing - where is the air gap required to be?

Yes, Jerry much better phrasing than I. I was too disgusted by what I saw to use the simple 'running trap' terminology. Interesting diagram without the air gap. I'll have to check into that. Is that a newer or older, which brand diagram. I've seen a lot of diagrams over the years that show the air gap.

Originally Posted by Markus Keller

Is that a newer or older, which brand diagram.

Markus,

I believe that was from a Carrier installation instructions. That is from an older one, but newer ones show the same drawings.

Interesting diagram without the air gap. I'll have to check into that. I've seen a lot of diagrams over the years that show the air gap.

The only air gap for condensate drains that I am aware of is when it drains into a sanitary sewer, in that case it needs an air gap between the condensate drain line and the sanitary sewer.

flexible vent connectors can either be the listed types or unlisted but would need to meet the code requirements and be approved by the AHJ. If this flex hose has listing stickers for UL 441 and factory made adapters on each end then it is probably listed. If it appears to be chimney liner with no adapters or listing stickers then it probably is not approved. If it is semi-rigid and holds its shape well, its probably a listed connector while chimney liner typically will flop around. Cheap aluminum liner is very easy to penetrate while listed connector is more durable.

You also have to consider sizing--corrugated venting must be derated 20% plus another 20% for major offsets. That generally means you would have to use the next size up then reduce it right at the appliance collar. BTW, all the listed connectors I'm familiar with carry a 1" clearance to combustibles.

Originally Posted by Markus Keller

Yes, Jerry much better phrasing than I. I was too disgusted by what I saw to use the simple 'running trap' terminology. Interesting diagram without the air gap. I'll have to check into that. Is that a newer or older, which brand diagram. I've seen a lot of diagrams over the years that show the air gap.

Only guessing here, but could you mean "trap vent"? The vent is sometimes shown in there diagrams, but normally they are only required if local code requires it. Both the trap and the vent are nearly useless on a positive air system IMHO. While the trap will stop the loss of a very small amount of conditioned air, it only works when condensate fills it in the cooling mode. The vent is ridiculous as there will never be such a volume of condensate to siphon the trap dry.

Originally Posted by Vern Heiler

Both the trap and the vent are nearly useless on a positive air system IMHO. While the trap will stop the loss of a very small amount of conditioned air, it only works when condensate fills it in the cooling mode.

Small compared to what?

Should we also accept a quarter-sized hole the the coil case without comment or suggestion for repair?

Originally Posted by Bob Harper

You also have to consider sizing--corrugated venting must be derated 20% plus another 20% for major offsets. That generally means you would have to use the next size up then reduce it right at the appliance collar.

Thanks... never considered that...