ventless gas fireplace? bad idea?

bosshog24

My in-laws are replacing their wood stove with a gas fire place. The sales lady is trying to sell them a ventless model. I think ventless is a bad idea, but I need so evidence to support this view. Does anyone agree with me? Thank you

Unknown

I wouldn`t go for that,,

Check-out this simple video; http://www.youtube.com/watch?v=N2-1-kjExaM

Steamhead

The only thing we'll do

with a ventless anything, is rip it out. 

Tim McElwain

While your removing all the ventless

heaters you might also want to remove the gas cooking range as the oven and top burners are typically unvented and that is a total of 65,000 BTU's or more. The heaters are not much more than 40,000 BTU's..



Just a note concerning unvented heaters: There has never been an incident of Carbon Monoxide poisoning from a ventless space heater. Gas cooking ovens is another story. All ventless heaters have an oxygen depletion safety device that will cause them to shut off if the oxygen level in the home reaches 18% or less.



Having said all that I would not put one in my house because it is not very economical. I love my 8 year old pellet stove which heats my home about 75% of the time in the winter.

Unknown

Just curious Tim,,,

are you actually defending ventless heaters??

You say "All ventless heaters have an oxygen depletion safety device that will

cause them to shut off if the oxygen level in the home reaches 18% or

less",, if this is so what testing procedure is employed for its calibration??

Do we not have to get our instruments calibrated every 6 months or so?,, what about this "built-in" device?



No matter what they have built-in,, I still say it`s a BAD idea!

Steamhead

That's true

but if an O2 depletion sensor fails and the unit doesn't shut down, that could be a big problem.



I suppose what saves a kitchen stove is that people don't typically leave it unattended, they way they might with a heater.



Tim, did Providence ban the old-style unvented heaters the way Baltimore and many other places did? 

Jack

Here we go

Vent free appliances are safe. They are consistently oversized in the fireplace configuration. There are DOE sizing guidlines for vent free. VF are space htrs and as such should be sized for the space they are in. The sizing guidlines have three col. For loose, average & tight construction with each having t'stat and non t'stat col.



The average, t-stat unit in zone 5 ( way north, like New England) requires 3.85 btu/cuft according to the sizing guidelines. So, lets look at a 20X20X8 room of 3200 ft cu X the 3.85= about 12kbtu. Most VF fireplace are a min of 25 kbtu. Why? Well, because flame effect is what sells. Make a 12 kbtu vf fireplace and it will look like two Bic lighters on low.



VF units are "supplemental" heating. That means 4-6 hrs/day use. The problemis that people get them, they are cheap and they run the wheels off them. You then can have moisture issues. Personally, I can walk into a vast area with a VF unit running and I instantly know there is one in the space. It hits me right in the back of the throat, immediately. That does not happen to most people.



Tim is correct in everything he said about them. He is so darned boring...he is always correct...but I keep watching him;)



Apply and use them correctly and they are fine. It is just like everything else. Training, training, training. Tim is right there too!

Jean-David Beyer

what saves a kitchen stove is that people don't typically leave it unattended

Where I used to live, in an apartment in a so-called garden apartment complex, one guy was making french fries by dropping the cut-up potatos into hot fat on his stove top. The telephone in another room rang, so he went to answer it. By the time he got back to the kitchen, there was a major fire going on, so he threw water on it: not a smart move for an oil fire.



As a result, 14 families were homeless. Part of the trouble was that there were supposed to be fire-stops in the building between floors (between the vertical 2x4s) and between every other apartment; the builder did not put them in, so the whole place burned up.



I do not think anyone died from CO poisoning or oxygen depletion. In fact I think everyone lived through it. But I learned that people do leave stoves unattended.

Steamhead

Which is why I said

"people don't TYPICALLY leave it unattended". You can't fix stupid!

Jean-David Beyer

You can't fix stupid!

You are right! Where I used to work at engineering electronic equipment, there was a saying, "You can make something fool-proof, but you cannot make something damn-fool-proof."

Ex Maine Doug

Vent free or ventless

I always thought these devices came in two versions. One that vents outdoors and the other that vents indoors.  I have never seen one that has no vent (vent free) or one that is ventless (no vent).  Sounds like ventfree and ventless are marketing terms and not specs on how or where the unit relieves itself of the byproducts of combustion.   Maybe they should be labeled  vents inside or vents outside..

rich pickering

2 potential problems

The "sensor" is a precise orifice in the pilot burner, and you have no way of testing the accuracy.



The second potential problem is that at 18% O2, you have about 29,000ppm of something other than O2 floating around.



hmmmmmmmmm............

Jamie Hall

Check local codes

In some jurisdictions (like where I am) vent free gas fireplaces or heaters cannot be used in spaces which are for sleeping (a somewhat elastic definition, and somehat up to the AHJ), but can be elsewhere in the building.  Other areas may have different codes...



I've also noted that some places that sell them advise not to use them in sleeping spaces.  For what it's worth...

Charlie from wmass

Gas Stoves in Mass require a hood that

is vented to the outdoors. this helps move the combustion product out of the living space. I am with Steamhead, the only thing we do ventless is rip it out.

Tim McElwain

I hope when you rip it

out you have the customers permission. They are an authorized appliance according to NFPA 54 and the International Fuel Gas Code ( I will post some information from IFGC later).



As far as safety the ODS device is foolproof as it uses a special orifice developed in Europe with typically a quick drop out thermocouple (30 seconds or less) a normal thermocouple can take up to 180 seconds. I have tested many of these in the lab I ran at the gas company and most drop out long before 18% is reached. Almost any pilot attempting to operate in an environment of poor combustion will shut down or snuff out due to lack of oxygen. One of the products of combustion is CO2 when it is recirculated it will quench the flame and shut down is pretty much assured. This is why we do not have as many Carbon Monoxide issues as we could have.



There is a difference between an unvented and vented and there are ANSI standards for both. Vented "space heaters" or console heaters have been around for years. Wall furnaces using a type BW vent is another example. We have what are called decorative appliances often fireplace inserts which are vented.



Unvented heaters are usually under 40,000 BTU's and as I stated gas ranges one of the major appliances to cause Carbon Monoxide poisoning can be upwards from 65,000 BTU's. Not all have a vent hood and I can show you hundreds if not thousands in Mass that do not have a vent hood.



There is no ban in Providence or Rhode Island just very strict rules for installation.



I am not defending or encouraging anyone concerning these units just reporting the facts. You have to make your own judgements. I will say that every home should be equipped with a low level CO detector which alarms at 9PPM for safety beyond measure. I have five in my home and my children's homes. 

Tim McElwain

From the International Fuel Gas Code

SECTION 621 (IFGC)

UNVENTED ROOM HEATERS





621.1 General. Unvented room heaters shall be tested in accor­dance with ANSI Z21.11.2 and shall be installed in accordance with the conditions of the listing and the manufacturer's instal­lation instructions. Unvented room heaters utilizing fuels other than fuel gas shall be regulated by the International Mechani­cal Code.





621.2 Prohibited use. One or more unvented room heaters shall not be used as the sole source of comfort heating in a dwelling unit.





621.3 Input rating. Unvented room heaters shall not have an input rating in excess of 40,000 Btu/h (11.7 Kw).





621.4 Prohibited locations. Unvented room heaters shall not be installed within occupancies in Groups A, E and 1. The loca­tion of unvented room heaters shall also comply with Section 303.3.



 

621.5 Room or space volume. The aggregate input rating of all unvented appliances installed in a room or space shall not exceed 20 Btulh per cubic foot (207 W/m3) of volume of such room or space. Where the room or space in which the equip­ment is installed is directly connected to another room or space by a doorway, archway or other opening of comparable size

that cannot be closed, the volume of such adjacent room or space shall be permitted to be included in the calculations.





621.6 Oxygen-depletion safety system. Unvented room heat­ers shall be equipped with an oxygen-depletion-sensitive safety shutoff system. The system shall shut off the gas supply to the main and pilot burners when the oxygen in the surround­ing atmosphere is depleted to the percent concentration speci­fied by the manufacturer, but not lower than 18 percent. The system shall not incorporate field adljustment means capable of changing the set point at which the system acts to shut off the gas supply to the room heater.



 

621.7 Unvented decorative room heaters. An unvented deco­rative room heater shall not be installed in a factory-built fire­place unless the fireplace system has been specifically tested, listed and labeled for such use in accordance with UL 127.





621.7.1 VentIess firebox enclosures. Ventless firebox enclosures used with unvented decorative room heaters shall be listed as complying with ANSI Z21.91.

 

Tim McElwain

More from IFGC on Appliance Location

303 (IFGC) SECTION

APPLIANCE LOCATION

303.1 General. Appliances shall be located as required by this section, specific requirements elsewhere in this code and the conditions of the equipment and appliance listing.





303.2 Hazardous locations. Appliances shall not be located in a hazardous location unless listed and approved for the specific installation.





303.3 Prohibited locations. Appliances shall not be located in sleeping rooms, bathrooms, toilet rooms, storage closets or sur­gical rooms, or in a space that opens only into such rooms or spaces, except where the installation complies with one of the following:



I.    The appliance is a direct-vent appliance installed in accordance with the conditions of the listing and the manufacturer's instructions.



2.    Vented room heaters, wall furnaces, vented decorative appliances, vented gas fireplaces, vented gas fireplace heaters and decorative appliances for installation in vented solid fuel-burning fireplaces are installed in rooms that meet the required volume criteria of Section 304.5.



3.    A single wall-mounted unvented room heater is installed in a bathroom and such un vented room heater is equipped as specified in Section 62 1.6 and has an input rating not greater than 6,000 Btu/h (1.76 kW). The bath­room shall meet the required volume criteria of Section 304.5.



4.    A single wall-mounted unvented room heater is installed in a bedroom and such unvented room heater is equipped as specified in Section 621.6 and has an input rating not greater than 10,000 Btu/h (2.93 kW). The bedroom shall meet the required volume criteria of Section 304.5.



5.    The appliance is installed in a room or space that opens only into a bedroom or bathroom, and such room or space is used for no other purpose and is provided with a solid weather-stripped door equipped with an approved self-closing device. All combustion air shall be taken directly from the outdoors in accordance with Section 304.6.

 

Steamhead

For many years

we were taught that any unvented heater was illegal in Baltimore. Gas-fired, kerosene-fueled, didn't matter. The only thing that was allowed to be unvented was the usual gas-fired kitchen stove. Yes, I know these can produce much CO- my own stove was doing that when I got my first analyzer- but that's another topic.



I remember about six years ago (before Gordo and I started our company), going to a certain church in Baltimore that was converting an unused room to a classroom. They wanted us to run a gas line for the heater they had bought. When we saw it was unvented ("Vent-free" was the term they used) we called the chief inspector who said in no uncertain terms that the thing was illegal. No unvented heaters of any type were permitted in the city no matter what the occupancy. So we did not take any part in its installation. The preacher was not happy with the place that sold it.



This may have been part of the city's building code rather than the gas or mechanical code. I'd have to look it up. There was talk of changing this but the story changes regularly as to what they might permit. So as far as I know, unvented heaters are still not permitted.



Regardless, we won't have anything to do with them. If we see one- which is not often- we advise the customer to have it removed.

Unknown

Hey Frank,,

Remember those old unvented NG water heaters?

Were popular in the 40`s-60`s,,, they had a small 3" chimney cap mounted right on the top of the tank like an old train caboose stove vent. :-0

Steamhead

Yes, they look like they could be vented

But if they're not, the "Prime Directive" for unvented heaters applies. 

Charlie from wmass

Tim a little credit please

I always take into account my customers wishes. If what they wish for is against what I feel is safe procedure or is against code I step aside and say they have a phone book of people to call. I prefer living customers to ones who get what they demand. Living ones make for better repeat business. Unvented appliances were last installed by Charles Garrity the elder in the less than ideal neighborhoods of Glasgow Scotland in the late 1950's so they could finally get hot water. We do not do that anymore. If it burns gas we vent it to the outdoors or someone else can install it.

I prefer to use codes as my minimum not my maximum level of workmanship.

Tim McElwain

I was pulling your leg Charlie

and Steamhead. Please do not get me wrong I am not a big advocate of anything unvented, most of all gas cooking stoves. I personally have never put one in and really do not see too many of them most of what I see as decorative, ambiance type gas heaters is in high end homes in bathrooms and bedrooms and those are vented and installed according to code. I still say they are a waste of energy.

Tim McElwain

Bosshog24 let your inlaws

read this posting and then make a decision. I hope we have helped you out.

Unknown

Ya-right Tim,,,

A good way to cover your butt from the regular posters of this forum,,,, I almost forgot for a moment you are a businessman. If an  "unknown" would have said anything to the contrary, you would have crucified them! Good show.  :-)