Thread: Water heater vent connector

It seems the majority of water heater vent connectors are installed this way, lacking 12 inches of vertical extension. I am looking for where this requirement is written and cannot seem to find anything.

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Matthew,

Allegedly, it is in the fuel & gas code, but I have never found it either. Both JP and Bob Harper have posted on this in the past. If you search, you will probably find their posts. Of the manufacturer's installation instructions that I have seen, the wording has been to the effect that 1 foot vertical rise off of the draft hood is recommended. The problem with that is it is not a requirement, but a recommendation. Unless the fittings immediately off of the top of the water heater are really convoluted, I do not comment on it. I will check for proper drafting. However, that would be of limited value.

But, this will surely start another argument.

By the way, awfully late post to get an answer tonight.

No flex lines on the connecting pipes ?

Best

Ron

Ron,
To be honest, I did not know that was required. Installation in the photo is SOP around here.

Flex lines are not required. As a matter of fact, some areas do not allow flex lines. Here in CA, most people use flex lines to allow the water heater to move a little bit. Prevents leaks if the tank were to shift a bit. Earthquakes, you know.

I forgot to mention the foil tape. I have not found a foil tape that is approved or rated for flue use. But you already knew that.

Nice to know, because I would have missed a lot of missing flex lines

Matthew,

Interesting that you have earthquake straps. Your ground doesn't move, does it? Is that a requirement?

With a hard pipe fit. the water heater is set up dry. then the water is added. Due to the amount of water now in the tank 40 or 50 Gal. the pipes are now in a bind... everything just moved.
may not be a code but I call it out as a defect every time...

Best

Ron

Gunnar, Ron,
Thank you for the infor. Ron, I will start noting that. Gunnar, yes we are in a quake zone, there is a fault running through the salt lake valley. Some day the big one will wreck that place. The whole valley in sand so the liquefaction will cause a lot of damage. Park City area not so much, they say the Wasatch Mt Range will absorb most of the energy. Who Knows. But yes straps are required.

If you look at the vent connector tables in both fuel gas codes, you will see the tables start with a 12" vent rise. The insinuation is, this should be the absolute minimum rise. As Gunnar stated, it is a *recommendation* and not a flat out chapter and verse clear cut requirement. I can always backdoor it, too by the fact the system must work and putting a hard offset right on top of a draft hood is just asking it to do what it was designed to do----spill flue gases.

Tape not recognized for use on or with vent connector. It does not meet the NFPA definitions of noncombustible nor has it passed ASTM E-136 so it should be treated as a *combustible* which requires the stated clearance (6" in this case).

Note the soot staining at the TPR valve--a sign of vent malfunction.

Would like to know the size of the actual appliance connector off the draft hood. Is it a 3" with the 4" vent taped over it? Don't get me wrong--you need that 4" connector at min.. It may even require a 5": see the codes and listing.
Bob

Originally Posted by Bob Harper

Note the soot staining at the TPR valve--a sign of vent malfunction.

Bob,

Thanks for that. I see that all the time and have assumed it was just due to age or improper burner adjustment. Good to know.

Bob,
Wow I didn't notice that. Can you enlighten me how a vent malfunction results in soot around that specific area.

What you see is a steel jacket around an enclosed tank that has a flue up the center with a flame under it. If all goes well, the products of combustion go up the center flue past the draft hood into the vent connector and out. Now, if there is flame rollout or a weak draft, the flames can lick out past the bottom edges of the tank or soot and combustion gases spill. Instead of spilling just into the Combustion Appliance Zone (CAZ or room), these gases and particulates can draft up btw the inner tank and outer jacket. This space is heated and anytime there is fibrous insulation instead of foam or foam not in full contact with the outer jacket, you have a potential space that can draft. The soot rolls out the bottom, draws up btw the inner and outer, then some exhausts out around the TPR leaving an exhaust plume telltale. It's usually harder to see this at the draft hood.

Anything causing a weak draft or flow restriction in the venting can cause this. Often I'll wipe my finger across it first then take a pic so it stands out.

If a WH is burning properly, you shouldn't be getting any visible soot. All the more reason for a qualified tech to inspect and perform combustion analysis. Also, watch for flame rollout at startup. All WHs suffer from a little momentary backwash as the cooler air in the WH flue must be pushed out like a push-pop. I've seen flames shoot out of the outer jacket, which is why we maintain stated clearances as a min. When I see these soot tracks, I look closer at the degree of flame rollout on fire up and if it is sustained or not. Also, even once firing, you can get enough depressurization from leaky furnace ducts to pull some of the flame on the side of the WH facing the furnace to get some backdrafting. When you get flame impingement, you make soot as the gases are cooled.

Subtle little sign that not all is well. If you point out most WHs have this, I would agree and say yes, most WHs have venting issues.

HTH,
Bob

Thanks. Great info.

There is no UPC code requirement for a 12" vertical vent connector, however there are combustion clearances requirements, usually on the heater specifications its self. The minimum total vertical rise shall not be less than 5 feet. Water flex connectors aren't required, rigid connections do better in EQ, flex connectors have rubber washers the deteriorate over time and leak.