ODS or Thermostat Problem?


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Old 10-04-14, 05:09 PM
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ODS or Thermostat Problem?

Hello. I have a vent free gas log (Martin IND., Inc. Model VF24T) with a ODS manual pilot and thermostat control. You hold in the control knob and press the ignitor to light the pilot. After a minute or two, you release the control knob and then turn it from low to high (where it will turn the flames on and off automatically). There's a further selection where the flames will simply remain on.

The unit is probably 10 years old, and the problem that I'm having is that when it's set to turn on/off automatically, it will run for about 5 or 10 minutes and then "click" off and put the pilot out as well. Then, I cannot get it to restart for at least 10 minutes or so. This leads me to think that perhaps the ODS is defective.

I have attached photos of the parts in case that will help. I have found a complete replacement pilot unit here (ODS Pilot Assembly - Gas Logs Pilot - FastFireplaces.com), which looks identical to my parts and costs $95. What I need to know is how likely this replacement pilot is to resolve my issue, or should I purchase a brand new vent free log set with burner for about $250 (http://www.amazon.com/Sure-Heat-Rive...=ATVPDKIKX0DER).

Thanks in advance for your help!
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Last edited by Turpy; 10-04-14 at 06:10 PM.
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Old 10-05-14, 07:23 AM
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Maybe all that is needed to correct your issue is to clean the air intake hole. I circled the hole in red in the photo you originally posted. One of my family members was having the same issue as yours. I used a can of compressed air (used to clean computer keyboards) to clean the hole by inserting the straw and blasting it several times. It corrected the problem and is still working well. Anyway, it might be worth a try. If you have a shop air compressor to use that will work also.
 
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Old 10-05-14, 08:19 AM
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Thank you for that great suggestion firedawgsatx! I should have mentioned in my original post, that I have thoroughly cleaned this piece out with a toothpick as well as compressed air after reading that this is usually the cause and a quick and easy first step in troubleshooting gas log issues. Unfortunately though, it has not resolved my issue.

I do appreciate your input and willingness to help others!
 
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Old 10-05-14, 09:17 AM
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How does the flame look? Is it about 2" long and blue with a yellow tip? That is what the flame should look like. The only other things I can think of is to make sure the flame is hitting the thermocouple properly to heat it up sufficiently or possibly it has a bad thermocouple. It is difficult to tell from your photo but the tip of the thermocouple doesn't appear to be in very good shape.
 
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Old 10-05-14, 10:15 AM
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It's blue and about 2", no yellow tip (except just after light the pilot). There are yellow bits of flame that spurt out once in a while (about every 10-20 seconds). The pilot flame does touch at least 1/4" of the thermocouple. I ran the unit (without the logs in place) on the lowest setting that activated the flames, and it ran for about 5 minutes and then shut off normally (meaning that the pilot stayed lit). Now I'm running it on the highest setting (again without the logs in place), to see how log it will stay on and if it extinguishes the pilot as it shuts off the flames.

Most of the flames by the way, are a nice blue color. The very top 3-5 inches of them (when turned on high) are yellow. I'm guessing that it's not a pressure or gas quality issue. We get our gas from the local Vectren company, and it also runs our furnace. The furnace however, is a large unit which when run often to keep our very poorly insulated home at 75 can easily cost between $200-$300 per month during the 3-4 winter months. We do use small electric infrared heaters for zone heating, but I figure that running the gas log fireplace (with the flue completely closed) is by far the cheapest way to heat our large (16x36 8' ceiling) living room. When it stays running, it actually does the job nicely.

Well, after letting it sit over night, it's now been running on high for 30 straight minutes and it hasn't kicked off yet. This seems to indicate that it may not be a defective ODS, but rather perhaps something happening whenever the unit "kicks off" the flames to extinguish the pilot. I'll let you know as soon as it extinguishes the pilot again.

Thanks again for your help!
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Old 10-05-14, 10:59 AM
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The pilot flame does touch at least 1/4" of the thermocouple.
I suggest adjusting so flame impingement is between 3/8" and 1/2" to ensure it gets hot enough. Does your set-up have an adjusttment for the pilot flame?

Does your thermocouple have any build-up on it? Deposits can build up over time and affect proper operation. If there are deposits on it you can try and clean it off with some fine steel wool or light sand paper or emery cloth.

There are yellow bits of flame that spurt out once in a while (about every 10-20 seconds).
That would suggest the pilot orifice might need to be cleaned. I use a small wire out of a wire brush for that.
 

Last edited by firedawgsatx; 10-05-14 at 11:18 AM.
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Old 10-05-14, 11:34 AM
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I will definitely check the pilot orifice. I have no idea whether my unit has a pilot flame adjustment. It would appear that I can bend wither the pilot and/or the thermocouple to increase the amount of that is in the pilot flame. It's funny, I can't seem to get it to fail without the logs in place. I found thermocouples for sale online for around $5, but after reading about them on wikipedia, I wonder if I could replace it with the correct type.
 
 

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