DESA Vent Free Gas Log Shutting Off


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Old 11-18-11, 08:24 PM
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DESA Vent Free Gas Log Shutting Off

I have an interesting issue with a DESA natural gas log installed in my home. I don't have any real paperwork on the unit and apparently DESA went out of business in 2009 so I'm not going to have any luck on parts or advise from the manufacturer. It is a natural gas unit with a standing pilot light. It has a thermal sensor on it, and no remote or wall switch controlling it. If it would be helpful to post some photos, let me know and I will do so.

At any rate, the unit is shutting off intermittently. Sometimes it is after an hour or so, but most often it is after about ten minutes. The unit turns off and you can hear the valve assembly close. The pilot light is killed when this happens. If I then walk over, cycle the unit back to pilot and push the ignition, it comes right back on. I then turn the unit up to a higher temperature and it comes right back on. Then, around ten minutes later it clicks back off.

Any suggestions on how I could go about troubleshooting this and hopefully getting it corrected?

Thanks!
Chris
 
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Old 11-18-11, 10:42 PM
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Unvented gas equipment is a significant safety risk.

If you READ, UNDERSTAND and FOLLOW ALL the written warnings and direction specified by the manufacturer, I suppose they can be operated with a degree of safety.

But you don't have those warnings and directions. You can't operate it safely. The only safe way to operate the equipment you have is to disconnect it and leave it off.

Sorry.
 
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Old 11-19-11, 05:50 AM
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Desa Parts and Desa Tech Support Manuals Seems to have all the manuals and info as well as parts and tech info....
 
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Old 11-19-11, 04:43 PM
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So I presume the SeattlePioneer must work in the direct vent industry.

I do understand and follow all safety precautions for this fireplace. I've been a full time firefighter for 10 years and have never seen an issue with a vent free fireplace. I presume that's a good thing, though that's the only thing I can speak to.

Thanks for the link GunGuy. The manual seems a little thin and mostly speaks to normal operation. There isn't much of significance noted in the troubleshooting section.

Does anyone else have any general troubleshooting suggestions?
 
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Old 11-19-11, 10:14 PM
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Here is a link to one of the unvented fireplaces by this manufacturer:

http://www.desatech.com/manuals/Stov...113084-01K.pdf

If you read it, you will notice that pretty much the entire thing is a list of warnings about the potential hazards of this equipment.

Also pretty much the initial warning requires that only qualified people repair the fireplace. So your soliciting information on DIY repairs is just an example of how you and most everyone else ignores the safety warnings provided by the manufacturer. I think you'll find a similar warning on pretty much any unvented appliance. And in the case of unvented equipment it's very important that guidance be followed.

As a firefighter with ten years of experience, you are unqualified to have expert opinions on such equipment. You are merely equipped with overconfidence borne of lack of training and experience with such equipment.

I was a repairman for a utility company working on gas equipment for fifteen years. On the NUMEROUS occasions when fire departments were called out on gas leak or carbon monoxide complaints by utility customers, I was one of the people usually summoned by the fire department to evaluate the possible hazards of gas equipment.

Fire departments are just fine for pulling people out of imminently hazardous situations --- I called upon fire departments to perform evacuations when such services were needed.

But fire department personnel aren't competent to evaluate the risks of gas equipment.

I also operated my own independent repair service from 1994 to 2007 when I retired --- mostly repairing gas fireplaces.

And I have seen people injured by unvented gas fireplaces ---carbon monoxide poisoning. Vented an unvented equipment can both produce potentially lethal amounts of CO. But 99% of the time, vented equipment will vent those hazardous gasses outdoors, while 100% of the time unvented equipment will vent those hazardous gasses into the dwelling area.

So I suggest that unvented gas equipment is at least 100 times as hazardous as vented equipment. If those odds appeal to you, by all means keep using your gas logs. It's certainly no skin off of my nose.
 

Last edited by SeattlePioneer; 11-19-11 at 10:33 PM.
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Old 12-04-11, 01:18 PM
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Desa

I believe that FMI took over the Desa co. I am installing a direct vent from them and have noticed some info on Desa in the process. They(FMI) have live technical support which I have used several times on my install. Just google FMI fireplaces and follow the links. Just an FYI, my direct vent is also doing the same thing. Mine apparently is a venting issue, which I have yet to figure out. Same systems as you describe. I have installed other fireplaces and have worked with natural gas lines in the past, but this one remains a mystery. I will be interested to find out what your isssue is.
 
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Old 11-17-12, 10:05 AM
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Bad non answer to legitimate question

Cvecchi posted his problem a year ago so I assume by now he has solved his problem. I am posting to help with people who, like me, was looking for an answer to the same issue Cvecchi was having. I certainly did not find it on this site, and I must say that SeattlePioneer is totally, TOTALLY wrong about vent-free gas appliances. They are no more dangerous than any other gas fired heater.

The main reason ventless gas heaters are not dangerous is because they are all required by law to have an ODS pilot light that automatically shuts the whole unit off if it detects a low oxygen level, which is usually caused by the presence of carbon monoxide. Is it foolproof? Like any other mechanical device, it can fail. However ODS pilots pretty much always fail on the safe side. And that is what is happening to Cvecchi, unless he is really having low oxygen problems, which is very, very unlikely.

This problem is almost always caused by the two tiny air holes behind the pilot light getting partially plugged. These holes allow oxygen to get into the sensor and when they get blocked,even a little bit, the pilot goes through the procedure of shutting down the whole unit because it cannot detect enough oxygen. I had this problem with my free standing ventless stove. All you need to do is blow some air into the two tiny holes to clear them out. I have found that if I keep the area clean around my heater, this will never happen. At the start of each season, I vacuum down the whole heater, inside and out, including the gas logs. Then I vacuum all around the heater, especially underneath it. Then I use my air compressor to blow away any remaining dust, especially around the pilot light. Most importantly, I blow air into the two tiny holes on the rear of the pilot light.

Another thing to check is to make sure the pilot flame is touching the thermocoupler and any other sensor in front of the flame. My heater actually has three sensors. The main thermocoupler is a thicker metal cylinder directly over the flame, and then there are two other smaller sensors in front of the flame. This is another safety device found on all pilot lights to detect heat from the pilot light to ensure it has not gone out. If it cannot detect heat, it will also shut down the whole heater. That is why you have to hold down the pilot button when you first light it. It will not stay lit without the button being held down until the sensors heat up.

So I hope this will help other people who got to this site because they are having the same problem. Don't worry about these heaters being unsafe. Not only are they safe, but they are the most efficient gas heaters on the market, as no heat goes up your chimney. It all stays in your home.

So how can an unvented gas flame not be dangerous and spew deadly fumes in your home? Simple chemistry. Natural gas is a hydrocarbon, which means it is made up of molecules consisting of hydrogen and carbon. When heated and combined with oxygen, the hydrocarbon molecules break down and the carbon mixes with oxygen to form carbon dioxide and the hydrogen mixes with oxygen to form H-2-0, or water. So not only are ventless heaters very efficient, they also humidify the dry heated air. The only problem is that if there is not enough oxygen to burn the hydrocarbons, instead of producing harmless carbon dioxide, it produces carbon monoxide, a poisonous gas. That is where the ODS sensor comes in. I also have an actual carbon monoxide detector that I keep in the same room as my heater. In the 10 years or so I have had this detector, it has stayed at zero.
 
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Old 11-20-12, 06:15 AM
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No, the entire manual that SeatlePioneer linked to is not just a list of warnings. It lists pretty much the same warnings as any gas heater. The solution to the problem of the heater shutting off can be found on page 16 of this manual. It shows how to clean the small inlet holes of the pilot burner. These holes getting plugged up is what causes the heater to shut down.
 
 

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