How to Choose Between Blue Flame or Plaque Heaters

Updated on April 5, 2016

Wall Mount Convection Heater


The Fun of Winter

If you are looking for information about wall-mount heaters, I will assume that it is either winter and you want to warm up, or you are preparing for winter and want to stay warm. If one of these situations are true, then you are in the right place. We are going to cover the difference between plaque heaters and blue flame heaters, mention some of the names that people use for them too. And I will show you how to figure out how many British Thermal Units (BTU's) you will need to heat your space. Continue reading and hopefully I can help you and make it somewhat easier for you.

Propane or Natural Gas

In all actuality this question is not as important as it once was. A lot of units that are sold now can be used with either propane or natural gas. And to clarify a little more, when I say propane I am talking about liquid propane or LP. This would be hooking the heater up to a propane tank - great for portable situations. And natural gas would have a hard hook up. And this would be a more permanent situation.

In the overall picture of things it would be important to look at cost of fuel for both ways as well as cost of connecting to the heater. Some people do not want a tank sitting in one of their rooms and this makes the natural gas a more viable choice for them. Some people will only want the heater out during winter and may take it other places with them, and the propane option may be better for them. Either way, this is more of a personal preference and I do not need to go into further detail.

Side Note:

As a side note, some people call convection heat by the alias, "Blue Flame". Simply, because there is generally a blue flame at the bottom of the wall-mount heater. Note the above picture.

Convection Heaters

Convection heaters are a more traditional form of heating. Convection heat actually warms the air first. And you might ask, "What does that matter?" Well, if the air is heated first it moves much easier. If you have an old house with high ceilings, then this may not be the best heat source for you. Let's keep with the old house theory for now. The ceilings are high and hot air rises, so the air at your level that you want warm will be going up to the ceiling. And if the old house has drafts, the air is cooled from this even faster. Convection heat will not be the most efficient choice for you.

Radiant Heater


Infrared Radiant Plaque Heaters

New technology seems to bring in longer names, at least it seems that way to me half the time. The plague heater is a newer technology with the craze that is radiant heat. This has a screening that emits heat. Infrared radiant plaque heaters warm the humidity and solids in a room first. You would feel the floors and furniture warming up and by heating the moisture in the room it has less movement.

If we go back to the old house, this is the heater that is going to be more efficient. By heating the moisture, it moves upwards slower and the objects faster. So the heat is staying more at the level of the heater rather than a draft pushing it around. And for the home that is newer and pretty airtight, this heater would not be as good as a convection heater.

Easy BTU calculation

If you have eight foot ceilings an easy way to figure out how many BTU's you need is 30 BTU's per square foot. Or if you have higher ceilings then 3.75 BTU's per cubic foot. Most newer homes have eight foot ceilings though and this is an easier way to figure out BTU's.


As stated earlier, BTU means British Thermal Unit. The BTU is somewhat interesting, it is actually a unit of energy that equals 1,055 joules. A little more meaning is that a BTU is the approximate amount of energy it takes to warm one pound of water from 39 to 40 degrees Fahrenheit. When you are looking around at heating and cooling appliances and see a simply "BTU: 25,000" or whatever number, it is actually meaning BTU per hour. Now remember what I just told you - because it is pretty much useless and you will never need to know it.

What you will need to know to figure out how many BTU's you will need it the cubic feet you will be trying to heat. One BTU is sufficient to heat about 55 cubic feet by one degree Fahrenheit. So take the length and multiply it by the width. Then multiply this number by the height of the room. And you have your cubic feet. Now take that total cubic feet and divide it by 55. Keep the answer for later - we will call this number X.

Now take the lowest temperature you are expecting outside, and be realistic about this, and then figure out what temperature you would like to have it inside your house. Take the difference between the two by subtracting the low temperature from the desired temperature. Keep this number - we will call it Y.

Now take X and multiply it by Y. And the equation you have should bring back some memories: X * Y = X. And X in this case is the BTU's you will need to provide you with the temperature you desire.

Wall Mount Heaters

The overall message here is that there are different situations for different wall heaters. The technologies actually do heat things differently and this is an important thing to understand to get the best use out of the appliance that you use.

And understanding how to figure out the needed BTU per hour rating that will work for you. Once you understand the simply equations to figuring this out it will not be hard to buy what you need. And after reading this article I hope that I have armed you with the information you need to find what will be best for you. Good luck and stay warm!


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    • CJ Andrews profile image

      Chris Andrews 5 months ago from Norwalk, Ohio

      David, I appreciate all feedback. There are many aspect involved to be more precise, and I don't think the vast majority of people are going to have access to this. I can talk about insulation factors, date of build, type of building material, local wind factors, and the list can go on. Most people don't have the knowledge for the in depth detail and research that most of this would take so most retailers do find a way to measure for the average instead of the margins. I do appreciate that you raised awareness there was any confusion.

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      Gil 5 months ago

      Thank you all for the information, im trying too figure out the cost of running the unit. Just to make sure I properly understand the instruction. I have a room size 10' x 10' x 8' = 800 cubic feet divided by 55 = 14.54 number X. Desire temperature 70 degrees - lowers expected temperature 25 degrees = 45 number Y. X14.54 x Y45 = X654.3 Btu's per hour needed. 1 gallon of propane will yield 90,000 Btu's divided by 654.3 = 137.55 hours of heat. 137.55 divided by 24 hour in a day = 5.7 days of heat from 1 gallon. Im pain $2.60 a gallon, 31 days divided by 5.7 = 5.4 gallons x $2.60 = $14.14 a month total cost to run the unit, according to the formula above. Ill be using a 10,000 but init Dynamics's Glo blue flame. Is this correct

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      David Brick 5 months ago

      Chris, I enjoyed your article comparing blue flame with infrared vent-free heaters. It was very informative as far as that comparison goes. Since some people may still be reading your article, though, I feel compelled to let them know that your method for sizing the capacity of a heater is woefully inadequate. In order to properly size a heating system for a building, you need to know at what rate the building will lose heat to the surrounding environment under the most adverse conditions normally expected for the area in which it is located. The heating system must produce at least that amount of heat in order to compensate for those losses and maintain a constant temperature inside.

      The losses are a non-trivial combination of conduction, convection and radiation. The overall calculation has been greatly simplified by the American Society of Heating Refrigeration and Air Conditioning Engineers, but still utilizes a number of factors, including building construction type, insulation, infiltration, ventilation, etc., which your equation does not. In other words, ASHRAE simplified; you have oversimplified.

      By multiplying the interior volume of a home by the number 55, you are attempting to apply a very coarse sort of thumbrule that might work under a very specific set of circumstances, but would be entirely inaccurate for others. As "Bob" found, for example, your equation grossly underestimated his need for heating capacity.

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      Bob 14 months ago

      My calculations (using your formula) for my 8' x 16' x 8' enclosed insulated porch for a delta-T of 50F degrees shows a requirement of under 1000 BTU/hr. My trial with 3000 watts electric heat (10,000 BTU/hr) failed miserably. Other input such as yours consistently shows a need of almost 20,000 BTU/hr for the same conditions. Perhaps you're off by a few thousand percent!

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      CJ Andrews 17 months ago

      @Brenda I am glad that you looked for more information. Last year was a bad year for them as well. There was a dual fuel with most models that ended up needed a converter to work properly. This year it appears most models are either LP or Propane.

      @Judy my bees are telling me it is going to be a long fall, but my gut tells me it will be a harsh winter when it does hit us.

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      Judy 17 months ago

      Thank you, you are the first one that gave me the correct way to figure for BTU's. Now I will look for the correct heater.

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      Brenda 18 months ago

      Thank you. I backed out of buying last night when i realized i didn't have enough info. This just made my day.

    • CJ Andrews profile image

      Chris Andrews 5 years ago from Norwalk, Ohio

      The asterisk in the equation means multiply.

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      Charlotte 5 years ago

      Is the * in the equation a plus or multiply or subtract?

    • CJ Andrews profile image

      Chris Andrews 6 years ago from Norwalk, Ohio

      Thanks Steve! I appreciate your comment - especially since you are a pretty handy person.

    • StBriggs profile image

      StBriggs 6 years ago from Ohio

      Very informative. I know this is a topic I get a lot of questions about and you did a good job explaining the BTU's needed.