Any drawbacks to "ventless" heaters?

[john56h]

Any drawbacks to "ventless" heaters, like these?

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200332735_200332735

I'm considereing using two of these to periodically heat a 28' x 28' x 9' well insulated wood framed detached garage.

 

[oldgoat]

I have one in my 22 x 26 garage that is fairly well insulated. I bought mine from Lowe's but I think they are fairly generic. I bought the fan that was optional for it and it is pretty much a joke. Ended up putting a fan on a platform behind it to help circulate the air. Carbon Monoxide is a concern and I have detector for mine, but I have made a point also of not spending a lot of time in there at one time just in case. You will get more humidity in the building though and with mine it doesn't bring the temp up from the mid 30's to say 60's very fast. I can see it for the occassional use and for a backup in case electricity would go out, but if I was going to be spending much time out there in the winter or if I wanted to be able to heat up quickly I would spend the extra money on a regular garage heater.

 

[Roospike]

I would look for a vented heater and NOT a ventless ..........

Do a search at this site got get a lot of information. http://www.hearth.com/econtent/index.php/forums/

 

[Vicegrip]

They produce slightly acidic water vapor as a byproduct of combustion. If you have enough air exchange this is not a problem If the shop is tight you run the risk of rusting your stuff up.

 

[mike944]

I have one of those. They work ok, but only for ocasional heat. I definitely wouldn't reccomend it for long-term heat. The comments about water vapor are real. Windows fog up really fast. You also need to circulate the air somehow. Hot air rises, and your feet are still going to be cold unless you circulate the air.

Even if the CO levels stay acceptable, the combustion byproducts will still give you a little bit of a sore throat.

 

[HoosierBuddy]

I would second what everyone else has said. I have used a ventless heater in my barn, and it is definitely a second-rate solution. Carbon monoxide would be the least of my concerns, as all of the ventless products have an oxygen depletion sensor to protect from that. No. The biggest problems are the fact they produce gallons of water vapor under the best of cases, and noxious fumes if exposed to any vapors from paint, thinners, solvents, etc. They are also really touchy about dirt and dust getting sucked into the pilot assembly.

It's better than freezing your a%% off in an unheated garage...but only marginally so. Get a vented unit heater or furnace. You'll be much, much happier with it.

Phil

 

[Rustyd02359]

Quote:
Originally Posted by Rich1028
do they make moisture as well??

When oxygen and gas are burned the byproducts of complete combustion are heat, carbon dioxide, and water. If you look at the flue on any normal gas appliance, you will note a great deal of water vapor coming out of the flue. If you look at a high efficiency furnace, not only is there a large amount of water vapor coming out of the flue, there is also a steady stream being discharged into the condensate line.

There's nothing magical about an unvented fuel burning appliance that makes it any different. Unvented gas heaters are limited by code to the allowable BTU input. The burners are tuned very carefully to insure that they are set up to have complete combustion, meaning if they are working right they don't produce a measurable amount of Carbon Monoxide. They also have oxygen depletion sensors that monitor the ambiant air to insure that the oxygen level is not pulled down by the combustion process. The oxygen depletion sensor will shut off the burner if it starts burning "funny" because the combustion air doesn't have enough O2 in it. They are considered to be 99% efficient, because they burn cleanly and all of the heat they create stays in the structure rather than going up a flue.

BUT...they make water and a lot of it. I've seen cases where people tried to heat their homes with nothing but an unvented heater for a whole winter and it isn't pretty. Drywall falling down. Condensation coating the inside of the windows and pooling on the sills. It's a mold remediation issue waiting to happen.

Unvented heaters are great backup heat if the power goes out. They are great in fireplaces to run a couple of hours a day for extra comfort and ambiance. They are OK to run in a bathroom occasionally to take the chill off. They are outlawed by code in bedrooms. They are easily contaminated by solvents anywhere near them...even a little painting in the basement will cause the upstairs ventless fireplace to emit noxious odors.

They are fine if used as intended but can cause a lot of problems if used inappropriately. I know that heater companies are marketing ventless products for garages. Some people may even have had some sucesss with them. I never have. A "for real" unit heater or wall furnace that includes a direct vent would be a much better choice. A hydronic system would be the ultimate choice.

Phil aka Hoosierbuddy I think

 

[john56h]

Thanks for the replies. I appreciate the efforts you've all made.

 

[walt2002]

"
I would look for a vented heater and NOT a ventless .........."

I agree, a thru the wall sealed combustion chamber vented. A friend has a ventless in his shop and I hate to go over there when he is running it.

Walt Conner