Delayed ignition on gas log fireplace


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Old 11-29-13, 03:04 PM
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Delayed ignition on gas log fireplace

I have a Majestic DVR-36 gas log fireplace (purch in 2000) and I have a delayed ignition problem.

What happens: thermostat clicks on, small blue flame immediately appears on burner surface, but then it goes out. A half second later, BOOM it lights again, very high flame now. It doesn't do this all the time, but obviously it shouldn't do this at all.

I removed all the logs and vacuumed the burner surface thoroughly. (The burner surface has hundreds of tiny holes). I don't know what else to do.

Aside from calling a service tech, are there any other things I can check? The pilot flame is strong and steady. I am confused why the burner would light and then go out, the re-ignite.

Thank you.
 
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Old 11-29-13, 10:58 PM
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Yes....the burner has many holes in it that need to be clean for it to light correctly.
The holes near the pilot are the most important ones.

You have to find something to clean the holes out. One bristle from a wire brush, paper clip, straight pin, etc.
 
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Old 11-30-13, 04:59 PM
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Thanks for the reply. There are something like 5,000 holes in the burner, and as I started with a paperclip, it wasn't too long before I lost track of where I was. Not to mention it would probably take 1-1/2-2 hours to do this. I ended up using compressed air and blowing them out real good. Then I used a vacuum. Put it all back together, but unfortunately it's pretty much the same. About 40% of the time it lights, I get a delayed ignition. The pilot lights the main burner, but after a quick flicker it goes out, and then I get a small boom.

If you were diagnosing this, what would you do next?
 
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Old 11-30-13, 06:21 PM
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Clean the orifice where the burner tube connects to the gas line. It's usually brass with a small hole in it. Sometimes they are removable with a wrench for cleaning.
 
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Old 12-07-13, 03:04 PM
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PJ, thank you for the responses you've provided. I am hitting a wall with this thing. I spent a lot of time on it today, including observing what it's doing when.

First, I removed the logs again and got access to the orifice for the main burner and blew that small hole out with compressed air. I also blew out the opposite side, where the gas enters into the main burner. There were no visible signs of dirt or obstruction.

When the fireplace is cold, or when it's been off for 30 min or so, it starts up fine 99% of the time. However, the delayed ignition issue seems to occur when it is hot. For example, the t-stat is on 72, and the fireplace has just turned off. But it's colder out now, so I bump it up to 74. When it restarts, this is typically when I get a boom.

Now here's another observation: almost all the time when it does delayed ignition, once it does light, there is flashback, meaning gas down at the orifice is burning. This is accompanied by a louder "whooshing" sound from the flame.

Summing up, I've cleaned the ceramic burners with compressed air and vacuuming, and also cleaned the main orifice.

What to do next?

Thank you,
-Dave
 
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Old 12-20-13, 05:25 PM
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All fixed !!

Well I finally figured out why my gas fireplace was having problems with delayed ignition and flashback. Many hours of observation and thought here folks, lol. But in the end it was my own fault. What I kept noticing was the only time it would do this was when the stove was hot...or more specifically, when the fan was running.

There is a small hole under the pilot assembly, which allows the pilot feeder tube, thermopile, and igniter wire to pass through to the bottom area where the valve, fan, etc are. When I replaced the pilot feeder tube, I had to remove a lot of dried silicone sealant that was applied to completely seal that hole. When I put everything back together, I never bother resealing that hole. It wasn't readily apparent to me why it sealed in the first place. What can I say, I had a blonde moment.

When the fan is running, air is coming through that hole if it's not sealed. So when the gas tries to ignite, that flow of air totally messes with the process, and BOOM!

The solution very simply is to use Hi Temp RTV engine sealant and plug that sucker up good. Once it's sealed, the fireplace should be able to light with ease whether the fan is running or not.
 
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Old 12-20-13, 05:31 PM
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Isn't amazing how the smallest details can cause the most problems. Without being there and seeing that I would have never asked about it.

Thanks for stopping back and updating us.



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Old 12-20-13, 05:36 PM
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I know man!!! I LOL'd at myself when I finally figured it out!! Thanks for all your help too. I think I actually understand how this thing works now.
 
 

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