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How to Choose Between Blue Flame or Plaque Heaters

Chris has installed both types of heaters and used to supply a variety of heaters in both a commercial and residential capacity.

Radiant Heater

Radiant Heater

How to Choose the Right Wall-Mount Heater

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 is true, then you are in the right place.

Below, I cover the difference between plaque heaters and blue flame heaters, and I show you how to figure out how many British thermal units (BTUs) you will need to heat your space.

Propane or Natural Gas?

In all actuality, this question is not as important as it once was. Many modern units 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 mean hooking the heater up to a propane tank—great for portable situations. Natural gas would have a hard hookup and would be a more permanent situation.

It's important to look at the cost of fuel for both ways as well as the cost of connecting to the heater. Some people do not want a tank sitting in one of their rooms and this makes natural gas a better choice for them. Some people will only want the heater out during winter and may take it other places with them, so the propane option may be better for them.

What Is "Blue Flame"?

People call convection heat "blue flame" simply because there is generally a blue-colored flame at the bottom of the wall-mount heater.

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 rises. If you have an old house with high ceilings, then this may not be the best heat source for you since the warm air will collect up at the ceiling. And if the old house has drafts, the air will be cooled even faster. Convection heat will not be the most efficient choice for a grand old house.

Wall Mount Convection Heater

Wall Mount Convection 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 plaque heater is newer technology. It has a screening that emits heat. Infrared radiant plaque heaters warm the humidity and solids in a room first. You 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 a home that is new and airtight, this heater would not be as good as a convection heater.

A newer and more sleek radiant heater has more recently hit the market and this could be a great benefit to many. I have been impressed with the Heat Storm Phoenix Infrared Space Heater. The remote is very nice and this is a floor or wall mount unit.

Easy BTU Calculation

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


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 simple "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 BTUs you will need is 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 the total cubic feet and divide it by 55. Keep the answer for later—we will call this number X.

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Now take the lowest temperature you are expecting outside, and be realistic about this, and then figure out what temperature you would like it to be 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 simple equations to figure 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!

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: Between blue flame or plaque heaters, which would you recommend for a basement 2 car garage 30’x40’?

Answer: For a basement that size, If I was going to be using a wall mount, I don't think I would use one.

Question: We have an old house that is blocked and has 7-foot ceilings. Which type of heater would be best?

Answer: I would recommend a convection heater a.k.a. plaque heater. Since it heats the moisture in the air and object, the heat doesn't settle as high and with drafts it doesn't move as much.

Question: Which puts off less moisture; blue flame or red flame?

Answer: I am assuming you mean blue flame as in convection heat and red flame as in radiant heat. Blue flame is a common name for convection and plaque heater is common for radiant heat. It isn't that either of them give off moisture, but convection heat warms the actual air and radiant heats the moisture in the air.

Question: I'm using a blue flame gas wall heater in a 17x17 room that is on a cement slab. I've installed vinyl plank flooring. I use the heater in the spring and fall. After the room starts to heat up the floor gets very wet from condensation. Will using a gas plaque heater take care of the moisture getting on the floor?

Answer: There would still be some issue from the condensation. I do not imagine there would be a noticeable difference. If you kept it running and at an even temperature that would help.

Question: I have a vent free 20,000 BTU heater and want to know if I can use a regulator and hose off a gas grille to run my heater?

Answer: You would need to look at the psi for the vent free heater, but it should be okay to do this since both call for a low-pressure regulator.

Question: I want to heat two rooms with a wall-mounted propane heater. We have a wood stove in the kitchen and have an electric space heater in the adjoining bedroom. Both rooms measure about 2.303 cubic feet. Could I put my wall heater on the wall behind the wood stove or by the door of the bedroom?

Answer: I would look for better placement, and recalculate your space.

Question: Can you use wall heaters in small areas like horse trailers?

Answer: You could, although I would only do so with some caution.

Question: What's the best heater for a bathroom?

Answer: Completely matters on your heat source. Electric, propane, natural gas, etc..

Question: I have a ceramic studio on an exposed concrete slab with single pane windows and 2x4 construction. Leaking, to say the least. It's northern Ca. So our coldest is about 24 degrees and that's not very often. The room is 15 x 17 with a peaked ceiling so I averaging it at 11'. I come up with needing about 30000 btu's. Would a plaque heater fueled by propane be able to heat a room of these dimensions? My heater that just died is a big old cabinet beast that heated the ceiling better than the floor.

Answer: I would go with something slightly larger, mainly because concrete will continue to absorb the heat for a while and I don't know what insulation you have on the walls.

Question: Which propane heater puts off more Carbon monoxide? The radiant heate or blue flame?

Answer: I don't know specifically, the reason they are vent-free solutions is because they are designed to burn off the carbon monoxide and be safe for indoor use.

Question: Does one type of heater heat quicker than the other? For instance an enclosed snowmobile trailer when morning temps are single digits?

Answer: For these types of heaters, there is little difference. The blue flame would heat a little quicker but also disperse more quickly with a draft.

Question: I am planning on running a heater when I am working in my garage, which one is better?

Answer: I would recommend the plaque heater, although both will take time to heat a space up.

Question: We have plastic in our patio. What heater would be best?

Answer: I would recommend finding a space heater, plastic will not be a quality insulator and you would lose the heat very quickly.

Question: Vinyl plank flooring gets wet with a gas heater on a concrete slab. Would plaque heating be better?

Answer: This would have to do with sudden changes in temperature, if you had the unit set for a certain temperature that should help.


Connie on November 23, 2019:

I have a sunroom 300 sq. feet and it’s insulated, should I get a 10,000 blue flame or 2-plaque natural gas...

Chris Andrews (author) from Norwalk, Ohio on October 18, 2017:

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.

Gil on September 27, 2017:

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

David Brick on September 26, 2017:

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.

Bob on January 17, 2017:

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!

CJ Andrews on October 03, 2016:

@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.

Judy on September 28, 2016:

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.

Brenda on September 23, 2016:

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

Chris Andrews (author) from Norwalk, Ohio on November 02, 2012:

The asterisk in the equation means multiply.

Charlotte on November 02, 2012:

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

Chris Andrews (author) from Norwalk, Ohio on August 04, 2011:

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

StBriggs from Ohio on August 04, 2011:

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.

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