Gas Venting Concern for Water Heater

[Mark R. Long]

The vent for this NG water heater slopes downward, about 3/4" in 1' length before it goes into the larger vent from the NG furnace, which does a have sharp upward slope. Then larger vent then feeds immediately into a masonry chimney. Is this downward slope off the water heater appropriate?

[Mark R. Long]

Originally Posted by mlong

The vent for this NG water heater slopes downward, about 3/4" in 1' length before it goes into the larger vent from the NG furnace, which does a have sharp upward slope. Then larger vent then feeds immediately into a masonry chimney. Is this downward slope off the water heater appropriate?

Forgot to load my picture the first time!

[Darrell B. Hadler]

No, it's not right...it should have an upward grade of 1/4" per foot. Looks they ran out room to slope properly and didn't bother to re-do the tie-in in the proper location so they would have enough room for proper grade.

[Jeffrey R. Pope]

Originally Posted by mlong

Is this downward slope off the water heater appropriate?

Absolutely not. . .

[tallen]

Originally Posted by jpope

Absolutely not. . .

Ditto my man Jeff P.

Heated gas only flows uphill.

[Robert J. OConnor, P.E.]

The biggest issue with reverse slope vent connectors is that condensation/moisture/debris can build up at a low point. It doesn't appear to be a huge issue with that one assuming there are no low points between the elbow and the connection to the larger (furnace/boiler?) vent connector (hard to tell from such a small pic), and the larger one has correct pitch back to the equipment. But that doesn't make it right, and I would still write up the concern.

JMO & 2-nickels ...

[Mark R. Long]

Thanks for the replies, everyone!

[Mark R. Long]

Originally Posted by roconnor

The biggest issue with reverse slope vent connectors is that condensation/moisture/debris can build up at a low point. It doesn't appear to be a huge issue with that one assuming there are no low points between the elbow and the connection to the larger (furnace/boiler?) vent connector (hard to tell from such a small pic), and the larger one has correct pitch back to the equipment. But that doesn't make it right, and I would still write up the concern.

JMO & 2-nickels ...

I too, was not sure that it was a "big" deal since it was such a short run and it was close to the larger vent. That was the reason that I even posed the question. My "feeling" was that it was probably getting adequate draft.

Since this does deal, however, with a potentially lethal situation, I did write it up.

[Robert J. OConnor, P.E.]

Originally Posted by mlong

My "feeling" was that it was probably getting adequate draft ... Since this does deal, however, with a potentially lethal situation, I did write it up.

Even though determining adequate draft is beyond an inspection, adequate draft is another concern ... but at least in my mind not as big an issue as creating a low point since it's not a long run and/or severe pitch down to the larger vent connector from the pic/description (would be a significant concern in my mind if that was the case). But again it doesn't make it right, and I think you made the correct call to write it up.

JMO & 2-nickels ...

[Mark R. Long]

Thanks, Robert.

[Joseph T. Burkeson]

Originally Posted by roconnor

The biggest issue with reverse slope vent connectors is that condensation/moisture/debris can build up at a low point. It doesn't appear to be a huge issue with that one assuming there are no low points between the elbow and the connection to the larger (furnace/boiler?) vent connector (hard to tell from such a small pic), and the larger one has correct pitch back to the equipment. But that doesn't make it right, and I would still write up the concern.

I agree, additionally the low slope interferes with proper draft which creates a condition where back drafting is that much easier. It wouldn't take too much negative pressure to cause it, might be as simple as operating a clothes dryer and a bath fan at the same time.

These days when I inspect homes with natural gas I automatically add a note cautioning that it would be wise to replace one of the smoke detectors in the sleeping area with a combo Smoke/Carbon Monoxide detector.

[Mark R. Long]

Originally Posted by jburkeson1

These days when I inspect homes with natural gas I automatically add a note cautioning that it would be wise to replace one of the smoke detectors in the sleeping area with a combo Smoke/Carbon Monoxide detector.

I do the same if the home has any fuel burning appliance, gas, oil, wood, etc.

[Robert J. OConnor, P.E.]

Originally Posted by jburkeson1

... additionally the low slope interferes with proper draft which creates a condition where back drafting is that much easier. It wouldn't take too much negative pressure to cause it ...

More of a concern with a long vent connector or severe downward pitch after the elbow ... but again, it doesn't make it right, and is also poor practice.

Originally Posted by jburkeson1

These days when I inspect homes with natural gas I automatically add a note cautioning that it would be wise to replace one of the smoke detectors in the sleeping area with a combo Smoke/Carbon Monoxide detector.

Especially the CO detector if there is a sleeping room on the same level as the equipment ... and new smoke detectors throughout is always a good recommendation if the system is suspect/lacking.

JMO & 2-nickels ...

[tneumann]

If the hot gas will NOT GO downhill...where does it go in this situation?

[Mark R. Long]

Originally Posted by tneumann

If the hot gas will NOT GO downhill...where does it go in this situation?

Since you put the smiley face after your statement, Tony, I'm not sure if you were being serious or not.

The exhaust gases can possibly backdraft out into the room, the living space of the house. The exhaust vent on a water heater is not sealed at the top of the heater, there is a gap between the heater and the vent. So if the venting isn't working/drafting properly, fumes/carbon monoxide can easily backdraft into the room.