View Full Version : Vent free gas fireplace

Trent Tarter
06-17-2008, 09:54 PM
I have not inspected a Vent Free Gas Fireplace before. Besides odors emitted what are some of the other concerns that I should be warning my client about. This is in a small 600-700 square foot home about 100 years old with original single pane windows which will help with combustion air.

Nick Ostrowski
06-17-2008, 10:04 PM
I have not inspected a Vent Free Gas Fireplace before. Besides odors emitted what are some of the other concerns that I should be warning my client about. ...............How about "don't use it".

When I took the "Inspector and the Fireplace" course, I learned ventless gas fireplaces are not allowed in 16 states and are not allowed in businesses open to the public in some states.

I didn't like them before I learned all this. If the manufacturer recommends opening a window in the room when operating the unit, that tells me all I need to know.

David Banks
06-18-2008, 03:49 AM
A few comments. Some from MA code. Moisture being a big issue.

Unvented propane or natural gas-fired space heaters shall be prohibited in bedrooms and bathrooms. In rooms and buildings served by an unvented propane or natural gas-fired space heater, a primary source of heat, which is operable, shall be permanently installed and maintained in said building in accordance with 105 CMR (Department of Public Health).Sellers of unvented propane or natural gas-fired space heaters shall provide to each purchaser a copy of 527 CMR 30.00 upon sale of the unit.
Maintenance and Operation.
: The maintenance and operation of unvented propane or natural gas-fired space heaters shall be in accordance with the manufacturer's instructions. The manufacturer's instructions shall be left with the appliance and made available for any public official. Any malfunction of an unvented space heater shall forthwith be reported by the owner to the head of the local fire department.

: The use of un-vented gas fireplaces or heaters should be discouraged due to the possible negative effects of their operation in a cold climate.
: The potential for introducing unwanted carbon monoxide into the living area is certainly a disincentive to having these appliances in the home, but the addition of a large amount of moisture to the indoor air is an absolute certainty.
: Excess moisture can condense on windows or, even worse, it can be driven by positive pressures inside the house into attics and wall cavities where it can condense and allow mold and rot to develop.

Jerry Peck
06-18-2008, 05:58 AM
This is what I would explain to my clients (wording to this effect).

When we were young, unvented gas heaters killed people by burning up the oxygen in the air, leaving none for the sleeping people, suffocating them.

After enough deaths, the code prohibited the use of unvented gas heaters, as well it should have.

Nowadays, though, we have unvented gas fireplaces being used as unvented heaters, and there is one difference between the unvented gas heaters of old and the unvented gas fireplaces of today - namely that the unvented gas heater of old did not have the metal warning tags warning you of risk of death, the new unvented gas fireplaces do.

The new unvented gas fireplaces also state, on those warning tags, that you are to open windows and doors for adequate ventilation while the unvented gas heater is in use. I ask you - would you want to open the windows and doors and let the cold in when you are using the unvented gas fireplace for that comfy fireplace heating feeling? I doubt it.

That means you will be operating the unvented gas fireplace against the warnings attached to it, and, should you die, the attorneys for the unvented gas fireplace now have the upper hand and defense ... because *you* were improperly using the product *against the manufacturers instructions*. *THE SURVIVING SPOUSE* will more not get much from the manufacturer because you were mis-using the appliance.

Your choice: Use it as a decorative object, leaving the gas turned off, or risking death. Yes, it says so right here (holding the metal warning tags up) "RISK OF DEATH" blah, blah, blah.

daniel nantell
06-18-2008, 09:11 PM
I have one and I always crack the damper about 1 inch to let any c02 out of the house.

Nick Ostrowski
06-19-2008, 05:53 AM
Daniel, if you have a damper, then you have a flue for venting the gases which means it is not a ventless model. Ventless means no vents whatsoever, no flue, nothing. With a ventless model, all the combustion gases filter back into the room. Ventless gas fireplaces are generally one piece pre-fabricated units which are designed to be plopped down just about wherever you want in a house and not worry about having a chimney.

Bob Harper
06-19-2008, 06:18 AM
If you find the rating plate and the ANSI Std. listed is Z21.11.2(b), then it is ventfree. Some, however, are dual listed also to Z21.60 as a vented logset. If vented, the damper must be removed or permanently blocked to a minimum opening stated in the manual. I do Not recommend cracking the damper on ventfree. Down drafts can cool the flame and cause impingement thereby generating CO. Anything that burns produces CO2 including yourself. CO is the problem, along with gobs of water vapour.

Jerry, I would be careful with that comment about all the deaths from ventfree products. While I know you are talking about OLD units, the Ventfree Alliance is quick to point out there has never been a death attributed to an ODS pilot equipped burner. Just goes to show how poor our incident reporting systems are.

I doubt that house is big enough for a ventfree appliance. In sizing, you can only count the rooms that have fixed communication meaning if there is a door, the next room cannot count. Also, bedrooms and bathrooms carry special limits (10K & 6K BTU each max. and listed for that application in addition to sizing).

With cold single pane windows, they will have rivers of water on the window stools while running a ventfree appliance.

Jerry Peck
06-19-2008, 06:50 AM
I have one and I always crack the damper about 1 inch to let any c02 out of the house.


You need to open that damper *all the way*. Otherwise the fireplace could overheat and possibly even burn the house down.

Vented models do not have the heat build-up of ventless models, and are not designed (in many cases) to accept ventless units.

daniel nantell
06-19-2008, 02:45 PM
The fireplace was built as a wood burning fireplace , but I dont like the idea of carry wood and cleanup, so I installed a ventless gas log. Do you recommend a chimney sweep to evaulate the chimney when all they are buring is a ventless gas log.?????? thanks

Ted Menelly
06-19-2008, 04:48 PM
I did 2 additions where the folks insisted on the vent-less. I tried to talk them out of it. After the fact they both hated them. Every time they used them they both said it was hard to breath in the room I explained (what I explained in the beginning) about their proper use. They both had me change them to vented.

Personally I think they should be outlawed.

I don't like to be put in the position of "I told you so"

Just my opinion