BTU Ratings and a little secret…

As we field inquiries about our 12VDC marine air conditioner, I regularly find myself in the middle of a conversation about BTU ratings.  There are a number of 110V/220VAC marine air conditioner brands out there.  Did you know you basically have to trust the individual manufacturer to put a BTU rating on its product, and there’s no independent body in the industry to verify it?   If the label on the box says “12,000 BTU”, how do you know if it actually does provide that level of cooling?  

In the US, residential and commercial air conditioners and HVAC equipment adhere to very strict manufacturing standards, which also involve testing in isolated test chambers -- but none of this is applicable in the marine air conditioning industry.  Technically, a marine air conditioner manufacturer can label their product with whatever BTU they deem fit.  There is no controlling body to enforce it for the consumer.   It is a complicated and expensive process to gather performance data for an air conditioner; many marine air conditioner manufacturers don’t have the facility for accurate in-house capacity testing at specified conditions.  

Unless the manufacturer can validate with test chamber results there is only one certain benchmark a consumer can rely on – the compressor rating. Compressors have to be tested to certain performance levels at certain internal pressures; that is the only reliable empirical data in a marine air conditioner.  Most of the marine air conditioner manufacturers simply take this compressor rating at certain conditions and label the complete air conditioner to an estimated BTU level accordingly.  

The photos above are of a compressor from a common marine air conditioner brand, marketed as ’12,000 BTU’.  The compressor manufacturer’s specs for the same compressor show ’11,000 BTU’ rating. 

Let’s not forget that there are many other components in a system besides the compressor and the quality and effectiveness of these other parts, and how they are put together make a significant difference as well.  Price isn’t just a benchmark. Before purchasing a marine air conditioner, make sure to look for the labeling on the compressor. Reputable compressor manufacturers usually make all their test data available on their websites.  If the marine air conditioner manufacturer is not willing to give you the specs of the compressor, run away as fast as you can!!!