Thread: Soot on gas log set

I see this fairly frequently and just want to check and make sure I'm reporting it correctly.

To me, the soot on the logs says there's an improper fuel/air mixture. I had this happen on my BBQ sideburner once and the flame came out really orange and turned the bottom the pans black.

It turns out there was a spider web in the line just before the burner. A quick shot of compressed air and all was fine. I'm suspecting a similar blockage in this case.

This is in a 20 year old house and the seller reported they use the FP very seldom.

Any thoughts?

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Soot = Improper combustion.

Matt, the soot buildup definitely indicates something is amiss. All somebody has to do is move those ceramic logs out of the position they were designed to burn in and the combustion can be thrown out of whack. I think using the wrong log grate beneath the log set can do it too (I think).

Either way, it is a reportable condition for servicing and repairs as needed.

I agree. Enstein moved the logs around to impress the little lady and screwed up a sure thing. She probably ran out of the house gasping for breath, and for all the wrong reasons.

Is soot allowed on wood logs? I'm serious. What, in and of itself, is wrong with soot on gas logs as long as it stays in the fireplace and chimney?

Now, having said that, let me clarify a few points:
Ceramic vented logs are expected to soot up some. Some log sets have very specific placement while others leave it totally up to the homeowner. Ventfree logs MUST be in exact position. With most ceramic logs, you should try to minimize direct flame impingement, which leads to soot formation.

Proper combustion involves the old fire triangle of heat, fuel, and oxygen and combustion efficiency is time, temperature and turbulence. With gas logs, sooting is usually caused by cooling the flame ( such as by impinging on logs or embers or by too much secondary air) along with some inadequate mixing with oxygen. The reduced O2 may be caused by a closed or clogged venturi, esp. with LP or too much ember material over the burner.

With vented ceramic logs, expect some soot. More importantly, look to see if there are signs of spillage or not. Wether burning wood or gas, spillage is the real concern.

If this is a combination millivolt valve, shooting compressed air back into the burner orifice can blow the diaphragm and ruin the valve.

HTH,
Bob

That's why you're here Bob, to set us straight when we get off track. It was my understanding (apparently wrong) that gas logs sets should not get soot buildup on them, period. When does sooting on gas log sets (aside from ventless models) become a reportable issue?

The ceramic logs in or gas fireplace are totally black with soot and have been since before we bought the house.

The fire place is vented, with the damper fully open.

As best I can tell from the photo on the internet for the log set we have, I have the logs set right.

Attached is a photo from last December showing the fireplace.

Bob, is there any way to clean the ceramic logs? That way I can see how much they are sooting up now. This is original to the house, 30 years old now.

Well Nick, I would simply recommend a hearth specialist check out ALL hearth appliances and put it off on them. Most important is to locate the listed instructions.

Jerry, I'm having trouble seeing the logset because of your big noncombustible stocking. With vented logs, burn the logset for about 20 minutes until you have a good stable draft established. Shut off the burner and immediately brush off the logs. The draft will vacuum the soot up the chimney. There are products on the market where you pump spray it onto the hot logs. It causes the soot to release and draw up the stack. Do NOT try to use a household vacuum. Soot particles can be less than 0.3 microns, which is less than a HEPA vac. These ultra fine particles can remain suspended in the air for 8+ hours.

Nick, remind me to address this in Sept. when I speak at the NAHI Training Conference in Philly in Sept..

Bob

Originally Posted by Bob Harper

With vented logs, burn the logset for about 20 minutes until you have a good stable draft established. Shut off the burner and immediately brush off the logs. The draft will vacuum the soot up the chimney.

Bob,

Thanks, I'll try that.

We'll be replacing the burner and log set soon (I said that a year ago too, but now "soon" is that much closer).

Originally Posted by Jerry Peck

The ceramic logs in or gas fireplace are totally black with soot and have been since before we bought the house.

---is there any way to clean the ceramic logs?

These remove soot.

We get them at the locale janitorial supply house.

Split down the length after both sides get dirty.

http:Dry Cleaning Sponge - Soot Sponge for Smoke and Soot Removal

After several attempts at repair, the log set was replaced to correct the excessive soot production.

Even new can sometimes be defective. Replacement may be the best option.

Originally Posted by Joseph P. Hagarty

After several attempts at repair, the log set was replaced to correct the excessive soot production.

Even new can sometimes be defective. Replacement may be the best option.

Thats interesting to me as my own house has this same issue. I had the Company that I bought the gas fireplace from out to install the logs as I was getting soot on the glass and and side of house as in your pic. (Logs originally installed by the builder whom did the addition. Mucho impingement)
A Little better but still a problem. Bob do you agree that log replacement may be fix for this issue?