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

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SUMMARY

The discussion centers on the BTU output differences between a 24V DC heater from DC Thermal, comparing an older model rated at 3000 BTU to a new model claiming 18,000 BTU. The new model operates at 24V/45 amps, while the old model was 24V/35 amps. The calculation confirms that the new model's output is likely overstated, as it translates to approximately 3,700 BTU based on the conversion factor of 3.413 BTU per watt. Additionally, the conversation touches on battery size considerations for the heater installation, concluding that battery size is less critical if the alternator is consistently operational.

PREREQUISITES
  • Understanding of BTU and watt conversion (3.413 BTU in a watt)
  • Familiarity with 24V DC heating systems
  • Knowledge of electrical current ratings (amps) and their impact on heating
  • Basic principles of battery capacity and alternator functionality
NEXT STEPS
  • Research the specifications and performance of quartz-type heaters
  • Learn about the electrical requirements for 24V DC heating systems
  • Investigate battery sizing and capacity for high-demand electrical applications
  • Explore the efficiency ratings of different heating elements in DC systems
USEFUL FOR

HVAC technicians, electrical engineers, and anyone involved in the design or maintenance of DC heating systems will benefit from this discussion.

locknut
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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?