The radiant tube heater guys won't publish efficiency ratings but as non-condensing heaters they are generally somewhere between 50-80% AFUE (estimated closer to 50-60% on the high end for tube heaters) for non-condensing furnaces. High efficiency condensing furnaces can get up to 98% AFUE.
Some info on condensing vs non-condensing
Some info on radiant tube heater "efficiency"
My project: Climate zone 6A Hortonville, WI 54944 Energy source: electric or propane, no natural gas available An earlier post about heating garage brought up the possibility of gas powered infrared radiant. I'm familiar with these devices, but I literally can't find any information from the...
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The sales guys will always fill your ears with BS and lies until they get the sale then will ghost you when their taglines fail to meet up with the hype. You will hear "100% efficient radiant heat" but a butt-load of waste heat ends up going outside through the exhaust and does nothing to heat your building vs the cost of propane consumed.
I can tell you that my radiant heater system running propane costs an arm and a leg to operate and I keep the temps low because of the high operating costs at $2-$4/gallon of propane. If you don't want to believe reality come on over and we'll stick a thermometer in the exhaust pipe and you can see for yourself how "efficient" the combustion process is. Bring some beers while you are at it!
Standard ANSI radiant tube heater is 70% AFUE.
The manufacturer I'm familiar with per tube heaters offers radiant tube heaters in 75% AFUE, 78% AFUE, 80% AFUE and 82% AFUE. Those are published ratings by the way.
I consider myself somewhat familiar with conventional unit heaters. Most unit heaters sold for commercial applications are in the 80%-84% AFUE range (at least in my neck of the woods due to each of power venting the unit).
It's been while since I clocked a gas furnace, and I'll take your word for it on your tube heater That said, by using a tube heater, you won't need the same BTU output as you can get by with a lower BTU amount because you're not heating the entire area with a tube heater, but a specific area.
I'd need to look at some larger jobs done in the past, but so far, no complaints on gas usage, and that's from some that are on LP (as noted, most are commercial use).
I have no dog in this fight, only pointing out that if a conditioned space has a manual D done on it accurately and a tube heater job is laid out correctly, it will cost less money to operate in the long run gas wise vs a conventional unit heater.
Tube heaters probably get a bad rap, just like high velocity HVAC systems, just because they aren't laid out properly for commercial application (as noted, large garage doors opening and closing need to be paid special attention as to the garbage in, garbage out per how often and long they are opened).
That said, the upfront cost of tube heaters have a higher up front cost than a simple conventional unit heater along with a higher labor cost.
All that said, we can still agree to disagree
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