How do different types of elements affect the BTU output of a 24V DC heater?

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The discussion centers on the BTU output differences between an old 24V DC heater and a new model from DC Thermal, which claims significantly higher heat output. The old heater was rated at 3,000 BTU, while the new quartz type heater is rated at 18,000 BTU, raising skepticism about its actual performance. Participants clarify that the new heater's output, based on power calculations, should realistically be around 3,700 BTU. Additionally, there is a query about the importance of battery size in the installation, with the consensus suggesting that it may not be a concern if the alternator is always running before the heater is activated. The conversation concludes with a calculation indicating that at 27.5V and 45 amps, the heat output could be approximately 4,223 BTU.
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I had a 24V DC tractor cab heater that decided to let the magic smoke out shortly after hooking it up for this winter season.So,I checked the company website-DC Thermal-and they have the new improved models which claim to output almost 3 times the heat in BTU's.These are quartz type heaters.My old one was 24V/35amp and output was listed at around 3000 BTU.The new model uses a different type element and the rating is 24V/45amp with claimed 18,000 BTU output.In my small mind this seems questionable.The 18K rating is the same as my gas wall heater that will almost heat my entire house.

Another question is battery size for this installation.I use a PTO driven 70amp 1-wire Delco alternator that's hooked to two lawn and garden batteries in series.Don't know what the amp/hour rating is,but the cranking amps are around 360 ea.Does battery size matter in this install if the alt is always running before the heater is turned on?
 
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Your instncts are right: there are 3.413 btu in a watt, so the old one is properly rated and the new one can only put out about 3,700 btu.

I also wouldn't worry about the battery size if the alternator is always on.
 
Thanks for the reply,Russ.I'll tap your expertize a little further on this,if you don't mind.Dare I extrapolate that system voltage being 27.5V @45 amps which equates to 1237.5 watts,will the heat output raise to 4223 BTU's?
 

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