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Vent Free Nat. Gas Garage Heater

Guest Silverghost

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Guest Silverghost

I just bought a 20,000 BTU "Vent Free" Natural Gas "Blue Flame" Comfort Glow wall heater with an internal electric blower on close-out From Home Depot today. 75 % Off !

I have a two-car garage/shop at home which is under & inside my home.

2 +1/2 walls & an old wooden roll-up

double garage door are un-insulated and exposed to the outside cold. The forth wall is located next to my familyroom/den.

I had been using a 220Volt 20,000 BTU Dayton electric heater any time I wanted to work on a car in the garage. I do not run the heater all the time ! The extra electric cost of using this electric heater has gone through the roof~~~This is why I bought this new Natual Gas Vent Free heater.

I already have a 3/4" natural gas supply line going through the garge to feed a gas-log in my family-room gas fireplace. It should be a very easy gas & electric hook-up !

I am a bit concerned about using any "Vent Free" Natural Gas heater for two reasons~~~

First~~~ It is a garage with cars, snowblower, mower etc in it.

This Vent Free heater has a ribbon of blue gas flames behind a tempered glass front . The heater is NOT sealed.

My concern here is from the possible explosive gasoline fumes that may be lurking in the garage~~~

Would it be safe to use such a natural gas wall heater in a home garage/shop ?

This heater is said to be UL & UGI /AGA approved with a low oxygen sensor that shuts it off automatically for safety !

The pilot does not have to stay lit as it has a built in ignitor & self-contained thermostat !

Second~~~ The 20,000 BTU Natural Gas heater has NO outside venting. It is called ?Vent Free"

What about any possible Carbon Monoxide fumes ?

I never had a Natural Gas heater with no outside stack vent !

The exhaust fumes go directly intio the heating space !

Is there any risk of this ?

I can buy a cheap CO detector to install in this garge for safety .

Has anyone here ever used such a Vent Free Natural Gas heater before in their home or garage ?

Any opinions ?

Would YOU use it ?

Is it safe ?

Edited by Silverghost (see edit history)
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Guest 38cadillacjack

to me,anything that draws combustion air from where explosive fumes are present can't be safe.but once when my business was inpected by the fire marshall,was told that those fumes stayed 4' and lower so ceiling mounts were safe.he must have been right,we used dyes and contact cement and paint every day for 30 years,still alive.my advice,call your local fire person.i would rather read your stuff here than about you on the news.been enough cars and people destroyed by fire and carbon poison. good luck

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What happened to the open house at your 92 year old fathers collection today? We would like to know how well it went and how you enjoyed all of your guests seeing these long forgotten machines. Those of us who could not attend are dying to know.

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I use a vent free Comfort Glow for may basement shop area which does not have any gas fume concerns. Its rating is 10,000 BTU input and output is only 5,000 BTU. It barely takes the chill out of a semi insulated basement. In your description of your shop area, I think installing insulation would be a good investment. A shop of 400 Sq Ft with poor insulation requires 45,000 BTU/HR whereas the same fairly well insulated area requires 15,000 BTU/HR. The 20K unit you bought will probably struggle to keep up your "half insulated shop". Can you install 2 inch thick rigid foam insulation on the outside walls and on the door?? The seams should be either tongue and groove or ship lap joints. I suggest rigid foam to avoid having to build out a wall and use conventional fiberglass. Store the gas outside and drain the mower (not needed during winter anyway).

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Guest Silverghost


I saw basically two types of "Vent Free" Gas heaters built by Confort Glow ~~~at Home Depot.

The Blue Flame forced convection style, which I bought that heats the air in the room itself~~~


A similar looking Radiant Infrared"Vent Free" gas heater which only heats objects & people directly in front of them~~~

The objects then slowly heat the surrounding air.

Which type do you have in you basement shop ?

A 50% loss in BTU output from the amount of gas energy going in does not sound very good at all !

Edited by Silverghost (see edit history)
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  • 1 month later...

I have heard about the vent free heaters but have not heard good things about how well they heat. I think you will find that when fumes might be present you will want a sealed fire box that draws air from the outside so there is no chance of any fumes getting to the flame and igniting. I installed an over heard radiant tube heater, on propane, in a well insulated 24 x 24 (10' walls) shop and this past winter only cost around 300.00 to keep heat at 55 deg. all winter. Paid about 600.00 for the heater and 200.00 for installation. Well worth the investment to ensure safety and comfort.

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I have a vent free in a log cabin that I rent. It is recommended to not use it over a few hours a day, however, the tenants living there use it all of the time and wo problem. Yes, I have a carbon monoxide detector mounted and when I lived there, only used it for short durations. We have had no problems at all and the unit is now about 8 years old.

You would have no problem and the heat is quite good.

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ps-on the above mentioned calculations, I see no mention of ambient temperature and the desired temp inside.

Insulation value is a consideration, but ambient temperature readings both during the day and eve can vary greatly, depending where you live.

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Guest justjoe

I have seen many vent free heaters installed in garages and none of them people were very happy with. These things are unvented so the products of combustion end up in the conditioned space. A product of combustion is water (look at the tail pipe of your car), it makes a very damp space that really never drys out. Some even have have an oxygen sensor to turn it off if it burns up all the oxygen, that really makes you feel safe. They are supposed to have a ceramic type block that it burns against to reburn all of the unburnt fuel and eliminate all or most of the carbon monoxide. With tons of fresh air that may work, but to get the place warm you would need to seal up the place and that is the problem.

I would buy a Reznor or Modine hanging unit heater that has a b-vent chimney through the roof, or it could be side vented. Another option would be a williams direct vent wall furnace. The williams is a great garage furnace because it is sealed, it takes 100% of the combustion air from the outside and vents the flue products outside as well. It also is a counter flow furnace meaning it takes air from up high and the blows it down against the cold garage floor. If you are under a car in a cold garage that heat feels good.

I would take most sizing charts and throw them out the window, you are heating a garage and the most important thing is to get it to temperature to work as fast as possible. More often than not you are in the garage for 3-4 hours then not in it for a couple of days, any size furnace set down to 45 degrees will not waste much gas. Bottom line get a large heater, a 20x24 could even use a 45,000 btu.

hope my 2 cents helps


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