Thread: Return vent for HVAC above non vented fireplace

Would this be ok (return vent in basement den above non vented fireplace) I know the HVAC may not be running when this non vented fireplace is on, but since its non vented the off gases would be in the house anyway? (natural gas non vented fireplace with a central A/C furnace present)

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Originally Posted by Sam Morris

Would this be ok (return vent in basement den above non vented fireplace) I know the HVAC may not be running when this non vented fireplace is on, but since its non vented the off gases would be in the house anyway? (natural gas non vented fireplace with a central A/C furnace present)

Hi Sam,

As shown not a concern.
* vented appliance / solid wood or gas would require a10 f00t clearance.

A non-vented gas fireplace is allowed in your area?

Originally Posted by Mike Kleisch

A non-vented gas fireplace is allowed in your area?

Yes, sure has

The heat/gasses will rise into your return. Problem when running both. Non-vented natural gas fireplaces scare me. My spider senses tingle when I get near them. My neighbor nearly killed himself with a kerosene heater. My belief is that they should be vented as a furnace or a water heater is. But - they say different. It's your air too breathe. Good luck.

I am not familiar with your local codes and do not wish to debate legal or not legal. Having said that; there is nothing good about that installation.

The combustion gasses are being distributed via the duct system throughout the entire home.

Originally Posted by Steven Turetsky

I am not familiar with your local codes and do not wish to debate legal or not legal. Having said that; there is nothing good about that installation.

The combustion gasses are being distributed via the duct system throughout the entire home.

Your right Steve as with any vent less gas appliance ( return vent or not )

Its winter, its cold, the house is buttoned up, you have a nice romantic evening on the bearskin rug in front of the vent gas fireplace, forget to turn it off when you leave the room, furnace runs through the night sucking the gas ventless fireplace fumes up into the return, distributes them throughout the house ... you don't wake up in the morning.
As I tell all my clients, use it as decoration or throw it in the alley.

A non vented gas appliance still emits CO ..nonvented appliances always need a fresh air make up close by if not the quality of the air deteriorates.

- - - Updated - - -

A non vented gas appliance still emits CO ..nonvented appliances always need a fresh air make up close by if not the quality of the air deteriorates.

Here in the Pacific Northwest, not only do we need to vent all combustion appliances but we have to do detailed pressure testing to make sure those appliances do not back-draft when exhaust fans and HVAC is on. An unvented gas fireplace would be red tagged by the local gas utility without question. This home needs carbon monoxide alarms everywhere. I would put one on by the fireplace, each level of the home, by the bedrooms and by a furnace supply vent. I personally like the alarms/monitors that have a digital read out of the PPM because you now exactly what the concentration is and many also keep a memory of readings in case no one is home when the problem arises.

Originally Posted by Ben Tressel

Here in the Pacific Northwest, not only do we need to vent all combustion appliances but we have to do detailed pressure testing to make sure those appliances do not back-draft when exhaust fans and HVAC is on. An unvented gas fireplace would be red tagged by the local gas utility without question. This home needs carbon monoxide alarms everywhere. I would put one on by the fireplace, each level of the home, by the bedrooms and by a furnace supply vent. I personally like the alarms/monitors that have a digital read out of the PPM because you now exactly what the concentration is and many also keep a memory of readings in case no one is home when the problem arises.

So you need to vent all ( even those Manufactured as Vent less ) gas appliances ?

The only natural gas combustion appliance that gets a pass in existing construction is a gas oven/stove. In new construction, a oven hood which vents to the exterior is required. It is an absolute rule that if elevated carbon monoxide is present in the home, no weatherization may happen until that problem is fixed. The major push here is to tighten homes as much as possible, so we definitely do not want a heating source spilling CO. If I saw this in a home, it would be a huge red flag. Honestly, I would walk away from the job if the homeowner didn't agree to get rid of it.

Originally Posted by Ben Tressel

The only natural gas combustion appliance that gets a pass in existing construction is a gas oven/stove. In new construction, a oven hood which vents to the exterior is required. It is an absolute rule that if elevated carbon monoxide is present in the home, no weatherization may happen until that problem is fixed. The major push here is to tighten homes as much as possible, so we definitely do not want a heating source spilling CO. If I saw this in a home, it would be a huge red flag. Honestly, I would walk away from the job if the homeowner didn't agree to get rid of it.

Ben,

I agree that a gas appliance used as a "Heating Source " needs to be vented.
*what is being discussed is a not a Heat Source but a decorative appliance.
** if not used per the Manufactures Instructions could be hazardous.
http://literature.mhsc.com/majestic/...6_33ISDG_4.pdf

thanks for the clarification Billy. I guess it doesn't seem so crazy now. Still a bad idea tho.

Originally Posted by Ben Tressel

thanks for the clarification Billy. I guess it doesn't seem so crazy now. Still a bad idea tho.

Yeah,

Kinda like Drive-thru Liquor Stores.
*but what ya gonna do.

Originally Posted by Billy Stephens

Ben,

I agree that a gas appliance used as a "Heating Source " needs to be vented.
*what is being discussed is a not a Heat Source but a decorative appliance.
** if not used per the Manufactures Instructions could be hazardous.
http://literature.mhsc.com/majestic/...6_33ISDG_4.pdf

Billy, I don't quite get the gist of your post. Maybe I am misunderstanding you. What is the difference if it is being used as a heating source or as a decorative appliance? if it is burning it is emitting CO.

Originally Posted by Steven Turetsky

Billy, I don't quite get the gist of your post. Maybe I am misunderstanding you. What is the difference if it is being used as a heating source or as a decorative appliance? if it is burning it is emitting CO.

Volume.

Anything that burns emits harmful by products. Cigars, Candles, Fondue, Frying an egg cooking or baking in a Gas Stove.

* decorative use ( ambiance ) for short periods of time not installed in a bath or bedroom with amble makeup air per the Manufactures instructions.

**Primary or supplemental heat source without makeup air ( using the appliance outside its listing ) very hazardous.

Originally Posted by Steven Turetsky

Billy, I don't quite get the gist of your post. Maybe I am misunderstanding you. What is the difference if it is being used as a heating source or as a decorative appliance? if it is burning it is emitting CO.

Used as a heating source - you go to sleep and 'wake up dead'.

Used as a decorative appliance - you turn it off before going to sleep (theoretically, anyway).

A gas oven is allowed by ANSI to emit 800ppm CO AF because it's use is usually (love that part) limited to once or twice a day at a max. of about 3-4 hrs. per use. Therefore, IF....your home has the min. 0.35 ACH then theoretically, the ambient CO levels would remain under actionable levels............according to the great minds of the world. BTW, a ventfree appliance can emit 200ppm. And you thought it was the L-tryptophan from the turkey making you sleepy at Thanksgiving. Put a pot of cold water on a gas range, fire it and read the ambient CO. Now, crack the oven door, set it to "broil" and read the ambient CO. Be ready to remove your sensor before it pegs too high. Now, line the oven bottom with tin foil and repeat.

As for what alert device to recommend, understand the shortcomings of the UL 2034 listing for CO alarms:
You can breathe 69ppm for up to 30 days or 70ppm up to 4hrs. before a listed alarm is *supposed* to alert. I say supposed because they have a terrible track record of failure to alert at required levels or even at all. Now, for the fun part- the UL listing is based upon alerting only once a person in that space breathing the air achieves a carboxyhemoglobin level of >5%. Great! It alerts to wake me just before I pass out and die to warn me to escape. These alarms are NOT designed to protect against CO poisoning! They are designed to protect against CO death! To that end, they often fail miserably.

Do yourself a favor and get unlisted CO monitors that alert at 15ppm after 60 seconds, are very reliable, don't alert false positives, and are very accurate.