Ventless fireplace

I need some help on ventless fireplaces. Are ventless fireplaces only electric or can they also be gas. I was under the impression they could be gas also. Inspection today I had a gas log set in a manufactured fireplace with no exhaust flue/chimney. It had a gas cut off at the wall and a control knob and igniter under the gas logs themselves. First time to see this setup. I am wondering how this unit is vented. Any comments would be appreciated.


Looks like a gas valve on the right side of your picture.

Was there a vent in back of the unit at the exterior wall?

Most manufacturer’s instructions state:

  1. Don’t operate for more that 2 hours in any 24 hour period.
  2. Always provide exterior ventilation (open window) when operating.

Make sure that the client has the operation instructions.

I call them out if they have no thermolcouple.

deffinetely a vent free system. First time for me. I really dont like the idea.

Yes, gas ventless is very common (and some say unsafe, although I’m not convinced).

Here are some comments I use whenever I see one.

“According to today’s standards, manufactured fireplace clearances are determined by the manufacturer. The buyer should consult the manufacturer’s manual or otherwise contact the manufacturer to determine if the clearances are adequate.”

“Gas cutoffs are acceptable inside a gas fireplace firebox, if the manufacturer approves it. Consult the manufacturer’s operator’s manual prior to operation of gas logs.”

I don’t like them much either----but think of it this way-----how many gas ranges do you see without any means of venting?

True. But still you have to vent products of combustion.

I have a gas range and I have to remind myself to turn vent on when I use it.

The products of natural gas combustion from gas logs (or stoves) with blue gas flames is very little CO (mostly water vapor I think).

My mother heats one room of her house, with the doors and windows shut in that room, with ventless gas logs and the CO monitor has never made a peep.

That’s true for natural gas or LP, as long as the burner is working properly - if not, the flame will show other than blue - yellow, orange, and it is not efficient, then it gives off CO. Dust, dirt, rust, etc can clog or foul the burner. If it goes on for awhile - it’s nap time…:ack!: (X})

Here is one of the mfgs. of vent free gas logs:

These units are 99% efficient. There are restrictions for use in tight construction as the unit uses room oxygen for combustion. Read the operating and installation instruction links on the above link for more info.

Maintaining a clean air intake for combustion efficiency is important per manufacturer’s instructions also.

I became aware of gas Direct-Fired air handling units when I worked as an engineer for a compliance lab before becoming a HI. The gas guys in our lab would test these units for compliance. They are built to very stringent standards with regard to burn efficiency and combustion products released into the heated space. These particular units are intended for commercial applications only. I found an introductory course that will give anyone interested a good overview of the issues with this type of heating unit and a decent understanding of their application.
This is from the introduction:

*This course is intended to provide the student with an understanding of the operation and application of heating systems that utilize Direct Gas-Fired Burners to provide comfort heating of building spaces. Typical applications are shown. Symptoms of problems that may be addressed using this type of equipment are described. Basic system configurations are discussed, with descriptions of options that are available. Basic operation of units, with a discussion of fuels, air quality requirements, operational limits, and installation requirements are presented. Industry Construction Standards and Codes are listed. Insurance standards are also explained. Safety issues are addressed.

*You can read the entire document here:

I agree!! The reason Joe’s mother has not had a problem is that the room{house] is not "tight"it has air infiltration.And therefore supply air.

To operate safely you need a good supply of air and effective venting that carries exhausts outdoors.

I have not seen where any one has mentioned that they do use Oxygen . No oxygen and Good night .
Not legal in Canada . And will never be in my home .
Some one mentioned Gas cook stoves they are not usually used constantly and not on steady like a gas fire place could be
Roy Cooke

Read my post earlier today.


That’s a given,for combustion to occur you need HEAT,FUEL,AIR {air by the way only has about 21% oxygen} If combustion is complete carbon monoxide is not an issue.Supply of air and proper venting is an insurance policy for users of fossil fuel burning equipment.That,maintenance of equipment, and a good carbon monoxide detector!!

True. Her house was built in 1973, so O2 has never been a concern.

Would you have one in your home ?
as I said Not legal in Canada And never in my home .
Consumers report had a good write up a few years ago about how unsafe they are.
Roy Cooke

Well yes I would. I fact I have a 30,000 BTU unit hanging on the wall in my kitchen for the last 5 years. We use it for morning warm-ups in our pre 1900 farm house that despite my best efforts at making energy efficient still leaks sufficiently to provide more than enough combustion air. I also have a high output gas rangetop. Neither are permitted in sleeping areas.:shock:

Roy, read the link above on commercial gas direct-fired air handlers. We use these types of air handlers in the gym of our local high school.

The ventless fireplace logs are becoming more popular as gas prices rise. They are generally limited to 32,000 BTU as opposed to the standard vented units that can be as high as 80,000 BTU and have only 20% efficiency ratings.

A very VERY important read on Ventless Fire places…

Roy Cooke