Gas Logs, To Vent or Not to Vent........

   / Gas Logs, To Vent or Not to Vent........ #1  

stonebase

Bronze Member
Joined
Nov 20, 2003
Messages
84
Location
Volant, PA
Tractor
Kubota L3130
Hello Everyone,

As winter approaches I am researching brands of gas fire logs to buy for our home. The home is newly constructed (July this year), total electric, no natural gas so I am working out an agreement with a local fuel supplier for a 100 gallon propane tank which they will keep filled throughout the year. The house was built with a manufactured, zero clearance woodburning firebox that was converted for approved gas use (knockout hole, 1/2 inch lead pipe into box, valve switch & key in floor, pipe stubbed out back exterior wall near chimney)

I hope someone has some experiences with the different types of logs to perhaps make my decision more clearer. The big dilemma seems whether to buy vented or vent free logs. Here's the breakdown, the vented sets are not very effecient energy sources (20-30%) and are basically for appearance and ambiance. To add to the disadvantages, by code, a damper clamp must be installed with these sets that keeps the damper partially open AT ALL times so you are losing heat up the chimney even when the set is not fired up. On the other hand, the vent free sets are very efficient (95 %) and are approved as secondary heat sources (in event of power outtage, etc...)

OK, decision seems like a no brainer? Not actually, as I begin to shop around for these sets there seems to be quite a bit of negative publicity concerning these vent free products, alot of rather serious warnings and disclaimers concerning their installation, etc which really makes me have second thoughts.

First of all the manual provided by the builder for my firebox states in a very vague manner that the product has not been tested and approved for use with an unvented product and not to use a gas log set (un vented) unless that it has specifically been tested for use in this type of firebox. When you look at the literature provided by the log manufacturers it is just as vague. Most just say they are approved for use in solid fuel fireplaces and manufactured fireboxes although a few add the disclaimer (exception, do not use in a product whereby the manufacturer states their product has not been tested with unvented logs) They really dont come out and say they are approved for MY fireplace. It seems that all these manufacturers put alot of effort into wording these statements in order to cover their liability. When you ask dealers at the fire place stores they are divided 50-50 on the issue, some wont even think of placing a set in my situation and some dont think anything of it.

I realize this can be a very serious situation with the potential for fire and all but I would like to take advantage of the effeciency and have a back up source of heat in the winter since we are otherwise 100% reliant on electricity

If anyone has some experiences with this type of situation and would like to share their knowledge it would be greatly appreciated.

Thanks,

John /forums/images/graemlins/cool.gif
 
   / Gas Logs, To Vent or Not to Vent........ #2  
SAfety is an issue and I think some municipalities are starting to regulate un-vented gas appliances.

I have no experience with these log sets. I had a gas "woodstove" in my last house. It had a vent.

In the basement I had an un-vented wall mounted propane heater. It had an O2 depletion sensor so at the time I was not worried. But I forgot that a by-product of combustion is water. This thing caused my upstairs windows to fog over. Mold stared to grow on the basement walls. I could not figure out why - to my mind I was heating and therefore drying the place out. This should have been less hospitable to mold.

Anyway - the excess moisture is a big concern with an unvented gas appliance.

Phil
 
   / Gas Logs, To Vent or Not to Vent........ #3  
Odor. One thing I've noticed is the unvented ones leave a distinct odor when running. Same as your gas grill does. According to our gas guy, it causes some people to develop headaches.
 
   / Gas Logs, To Vent or Not to Vent........ #4  
In the best case scenario a new set of gas logs will be adjusted properly and not produce carbon monoxide even though you will always get a certain amount of water vapor added to the air since water is one of the byproducts of combustion. I would be most concerned about what happens if the combustion process of the gas logs gets a little out of adjustment by dirt, dust, spider webs in the orifice or venturi tube. If and when that happens you could end up with orderless carbon monoxide in your home, and that isn't good.

Oxygen sensors are put on products because those very same products are competing with you for oxygen in the same area in which they are placed. Think about that for a second, do you want to compete for oxygen with a set of unvented gas logs?

I would recommend a set of gas logs installed in your fireplace that uses some form of outside air for the combustion process and one that vents the combustion fumes to the outside of the structure. That way barring someone in your household forgetting to open the damper plate in the chimney there isn't much that could go wrong.
 
   / Gas Logs, To Vent or Not to Vent........ #5  
I have 3 fireplaces in my home. Two are conventional vented up a chimney, one is a high efficiency gas unit that we can use as a heat back up in case of a power failure and the generator fails (sort of like wearing a belt & suspenders).

We looked at all the options and chose a vented gas unit with a sealed glass chamber. We looked at it from pretty much all the different perspectives, but settled on one overwhelming issue. WHAT IF something goes wrong in the combustion and it starts to emit carbon monoxinde? WHAT IF the venturi gets damaged, becomes a spider nest, clogged, etc. The what if questions drove me to a vented unit.

Our unit has all the added whistles and bells so we can control the flames, run a circulating fan, etc etc There are lots of options with gas units and they can be a fancy or plain as you like, but the "what ifs" drove me to a vented choice.
 
   / Gas Logs, To Vent or Not to Vent........ #6  
One point to make here. Any home with gas appliances should have carbon monoxide detectors.

Ben
 
   / Gas Logs, To Vent or Not to Vent........ #7  
We have the ventless logs (propane) fireplace and have always left the window cracked that is only a few feet away. Just to be safe. That and to balance the temp...

The only time we notice any oder was on the initial burn in. You are supposed to burn them on high ( think) for atleast an hr before use with the windows and doors open. To burn off any exess chemicles left during the finnish proccess... and it will give you a headache to breath with the door closed and burn the eyes.

The builder even warned us to run it the 1st chance we got. But by the time we moved in and had propane it was already cold and we simply forgot to....

I will say regardless which way you go get the fully variable control valve. Ours has only high/med/ low and on low it will heat the house (1625sqft) till it's -to warm- to be left on full time...

This winter I have a small generator I plan to hook the tv/dss/ and the central heat fan motor to. As we rarely(knock on wood ) loose power for more than a day or 2...
 
 
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