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What would you say about this?


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Hi Rob

I only have the IRC in front of me and that does not appear to address the issue in your photo, but there is an obvious problem as can be seen in the siding above the vent termination. anyway for what it is worth here's the code (IRC2003)

G2427.8 (503.8) Venting system termination location.

The location of venting system terminations shall comply with the following (see Appendix C):

1. A mechanical draft venting system shall terminate at least 3 feet (914 mm) above any forced-air inlet located within 10 feet (3048 mm).


1. This provision shall not apply to the combustion air intake of a direct-vent appliance.

2. This provision shall not apply to the separation of the integral outdoor air inlet and flue gas dis-charge of listed outdoor appliances.

2. A mechanical draft venting system, excluding direct vent appliances, shall terminate at least 4 feet (1219 mm) below, 4 feet (1219 mm) horizontally from, or 1 foot (305 mm) above any door, operable window, or gravity air inlet into any building. The bottom of the vent terminal shall be located at least 12 inches (305 mm) above grade.

3. The vent terminal of a direct-vent appliance with an input of 10,000 Btu per hour (3 kW) or less shall be located at least 6 inches (152 mm) from any air opening into a building, and such an appliance with an input over 10,000 Btu per hour (3 kW) but not over 50,000 Btu per hour (14.7 kW) shall be installed with a 9-inch (230 mm) vent termination clearance, and an appliance with an input over 50,000 Btu/h (14.7 kw) shall have at least a 12-inch (305 mm) vent termination clearance. The bot-tom of the vent terminal and the air intake shall be located at least 12 inches (305 mm) above grade.

4. Through-the-wall vents for Category II and IV appliances and noncategorized condensing appliances shall not terminate over public walkways or over an area where condensate or vapor could create a nuisance or hazard or could be detrimental to the operation of regulators, relief valves, or other equipment. Where local experience indicates that condensate is a problem with Cate-gory I and III appliances, this provision shall also apply.



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Thanks for the info Gerry,

Got a call from the seller and with permission from my client, I informed him the soot on the siding and fascia was of concern and the fireplace should be inspected ..further evaluation etc.

I generally don't see discoloration from direct vented gas fireplaces. The guy (seller) is an HVAC student and tried to convince me because of incomplete combustion, yellow flame etc., it was acceptable to see this.

I suspect a gas adjustment or a vent problem.

Any other suggestions?

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Originally posted by RobC

I suspect a gas adjustment or a vent problem.

At a glance I'm inclined to agree that something is off, but I don't get his arguement that this sort of incomplete combustion would be acceptable. It would be wasteful and could be potentially dangerous. If you have the equipment and can get to it, you might try checking the CO output. A high reading should help confirm the potential danger for both client and seller. Plus the EPA says you can't vent more than 400 parts per million, period. I've seen two readings above that myself. If you found that the debate would be over; service required.

Brian G.

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We were discussing this earlier regarding introduction of moisture into the attic space and how that issue has been forgotten by the HVAC people.


The fireplace was turned off (gas), I didn't get a chance to test it.

I suggested that if he didn't like my recommendation he should write a letter of warranty to the buyer. I think that got the point across.

Has anybody else seen this condition, I'd be interested in hearing from you.


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Originally posted by RobC

Download Attachment: icon_photo.gif FireplaceGasVent_M.jpg

35.92 KB

It's a direct vented, zero clearance gas fireplace.

Any thoughts?

Sure. Just reach under the fireplace, take out the instructions and turn to the page where it says, "No smoke or soot should be present." Snap a picture of the page.

- Jim Katen, Oregon

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Did you look at the arrangement of the logs to see if they were arranged properly? Some homeowners don't like the arrangement of the logs so they rearrange them and end up impinging the flame, causing it to burn sooty like that. Major no-no.



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It didn't look like the logs had been disturbed, and the glass had just been cleaned. That's a good point because from my understanding they are certified with a particular log arrangement and to alter the design would decertify the appliance.

He told me he uses it every day to keep the main floor warm hence the reason for the soot.

So why would he have it shut off during a time of heating? It's suspect to me and my reason for service.

I was curious to know if any of you out there might have run into this problem in the past.

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Originally posted by Rob Amaral

Don't they deliberately poorly-tune those things to get them to kick out yellow flames?

Yes, they do. In fact the refer to a clear blue flame as "anemic" in the operating instructions. However, they also are quite specific that the flames shouldn't be so rich as to cause soot.

Here's a quotation from Superior. Other manufacturer's have similar wording:


Flame Appearance and sooting

Proper flame appearance is a matter of taste. Generally, most people prefer the warm glow of a yellow to orange flame. Appliances operated with air shutter openings that are too large will exhibit flames that are blue and transparent. These weak, blue and transparent flames are termed anemic. If the air shutter opening is too small sooting may occur. Propane models may exhibit a flame pattern that may candle or appear stringy. If this is

problematic or persists as the appliance is

continually operated, adjust the air shutter

closed as described in the previous paragraphs.

Operate the appliance for a period of time as the effect diminishes, ensuring that the appliance does not develop sooty flames. When satisfied that the appliance operates properly, proceed to finish the installation. Leave the

control knob in the ON position and the remote

switch OFF. Close the lower control compartment door.

I tried to attach the entire set of instructions, but they keep timing out. (Over 2,000 KB)

Bottom line:

* These things shouldn't produce soot.

* If they are producing soot, they should be fixed.

* The manufacturer's operating instructions say so.

* The code says to follow the manufacturer's instructions.

- Jim Katen, Oregon

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Amen JK...the devil is in the details. I'm starting to see more and more 'gas fireplaces' in the Boston area. Some of the new ones are really nice. My in laws have a hell of a nice one...the flames start out blue then change to yellowish after 5 mins or so. Has all kinds of whistles and bells that confuse the hell out of my WW2 vet father-in-law.... has a remote that keeps him busy being confused!

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