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Radiant or "Blue Flame" for garage heat?

fponzani's picture

I live in Northeast Ohio and want to add some heat to my garage. I'm looking at the Procom brand ventless gas heaters sold by Northern Tool and Harbor Freight, amonst others. These are sheet-metal units that can be mounted on the wall. They come in two flavors: radiant (heats the objects in the room) and "Blue Flame" (heats the air in the room). I understand the difference between the two, but I have been unable to find anybody who can tell me the pros and cons of each type as related to heating an attached garage.  I want to keep the temp in the 40's or low 50's and just turn it up when I'm working on a project in the garage.  Which is preferred? Has anybody here actually used either of these types of units?


(post #111354, reply #1 of 9)

I've used a blue flame type heater in a detached garage shop and liked it very much.  Don't know the pro's and cons vs radiant but really was very comfortable regardless of outside temp.

Also, I have one of those ventless blue flame models, Procom?, in my uninsulated 3-season porch.  Makes the room very comfortable in about 45 minutes on the coldest days.


(post #111354, reply #2 of 9)

I use a 15000/30000 btu  blue flame heater for my 600 sf shop. Works very well, runs on natural gas. I have been in shops that use radiant heaters, they seem to work just as well as the blue flame type. I keep the heater on the lowest setting overnight, unless the temperature goes into single digits, then I will set it on 2, this is about 20000 btu's.


(post #111354, reply #3 of 9)

Mike, thanks for the reply. Can you give a few more details? How warm is the shop when the heater is at lowest setting and it's, say, 30 degrees outside? How long to get it to a comfy working temp (65 degrees).  What is the configuration of your shop? Also, I'm not sure what you mean by 15,000/30,000 btus. Is this min/max settings?

Thanks, Frank.

(post #111354, reply #4 of 9)

Does anybody have any problems/ concerns with the ventless aspect of these heaters?  I have always been cautioned against them, but they seem to be the only ones offered for garage type use w/o getting expensive in a hurry.  I would also like to heat my attached garage this winter...... 

(post #111354, reply #5 of 9)

The USA is the only first world country that allow for the use of unvented heating appliances within the inhabited envelope of a building.

Canada forbids their use in houses.

The first issue is potential carbon monoxide if the units fails to burn properly.

Second issue is carbon dioxide. Although not toxic, it can asphixiate you as it lowers the concentration of oxygen in a house.  Breathing a high air content of CO2 will cause the lungs to accummulate fluid.  Stressful on cardiac/respiratory patients.

Third Issue. When you burn a hydrocarbon one of the largest byproducts is water vapor.  Adding extra water vapor to a house contributes to moisture problems such as mold/mildew, frost/rot in the attic, excessive sweating of windows and subsequent rot, trapped water in wall cavities. all hydrocarbon fuels there are a number of very small amounts of unlisted chemical compounds which are then burned and the remnants  released into the house and subsequently are concentrated with time for your inhalation.  Unknown & unstudied these micro amounts of inhaled chemicals may induce respiratory conditions and/or allergic reactions. 

If you burn something to produce heat....the byproducts need to be vented out of the environment you live & work in!!   Gas cooking appliance owner's manuals say NOT to use the cooking appliance for a source of heat. 

The American Society of Home Inspectors (ASHI) asks its inspectors to write all unvented appliances as a potential hazard.  This includes ventless fireplaces, spaceheaters, etc.

Unvented is Unwise!!!!

.................Iron Helix

.......Iron Helix

(post #111354, reply #6 of 9)

My guess is that most garage doors leak enough that a PROPER working ventless would not be a problem.

HOWEVER, the water vaport given off can be.

You have a cold shop and that means cold cast iron. Turn the heater on and you get instant hot air and heavy moisture. Followed shortly thereafter with condensation on the cast iron.

. William the Geezer, the sequel to Billy the Kid - Shoe

(post #111354, reply #7 of 9)

I actually have one of each so here are my thoughts.  Either produces alot of heat for the relatively cheap price.  The blue-flame is like standing in front of a gas burner on a stove so the heat all goes up.  If you have a high ceiling this might not be good.

The radiant style produces a more even feeling heat that warms your skin thru radiated heat waves.  If you're doing something strenuous this might not be good, but if you're on the other side of the shop you would definitely feel the heat whereas you might not from a blue flame type.

Knowing what I know, if I only had these two choices, I'd go for the radiant type.  However, . . .  if I may complicate the discussion just a bit, if I had a third choice, I'd opt for a Rinai (sp?) heater.  They are gas heat exchanger-type wall units that have a thru wall pipe to exhaust the bad stuff, and bring in the fresh stuff.  They're very efficient, have an easy to clean filter, and are not that much larger than the units you're looking at.  I'm sure they are more $ than what you asked about, but there's no exhaust, CO, or CO2 worry. I'm sure I've seen a website from some family owned business in Maine? maybe.  Here it is.

Be careful with an open flame when finishing etc. Good luck.


Edited 10/5/2004 5:58 pm ET by fingers

(post #111354, reply #8 of 9)

I agree with Fingers. A through the wall unit works best  no moisture no exhaust. As for radiant verses blue flame goes I work at UPS, we use hundreds of radiant heaters in our automotive shops they work great IF the units are left on all the time. In our case the shops are either manned 20 to 24 hours a day.  Radiant heat in a cold shop makes for unhappy workers. Radiant much like solar heat takes time to warm up the surroundings. The blue flame units can get your shop toasty much quicker. Secondly be mindful if you choose radiant units  of where you place them. In shops with low ceilings they can overheat the tops of taller items (i.e. the highboy chest you just stained). Lastly the reason we use so many radiant heaters is that a mechanic is always working in one of two spots his work bench or his bay once these areas are warmed by the radiant heat all the heat is not lost each time we open a door to move out one package car or tactor and bring in another.  That said, once you move outside the radiant heaters sweetspot it gets cold quick. With the blue flame you can turn on a fan an make sure the heats travels to where you want to work in your shop.

Good luck,


Which one to take? (post #111354, reply #9 of 9)

Hi there! Last monday i read about- r. Infrared Heater DR-988 Garage Shop 208/240V, 4800/5600W Heater with 6-30R Plug - Heats Up To 600 Sq Ft

So, this heater still cool in 2018? Or better to find something else?