Quote:
Originally Posted by Mobile Master Tech
Concerning flammable refrigerant fire safety, it is a good idea to make your flammable surroundings flameproof...One of the main tenets the NEC is built upon is that the 18" up from the floor including deeper pits or depressions (for heavier than air combustible gases like gasoline and propane) and the 18" down from the ceiling (for lighter than air combustible gases like natural gas) are the areas where they have different code requirements...Even if you add a 50% safety cushion, a 3 ton unit could safely live in a basement that is 18x18 having 486cuft of air in its lower 18". Build properly, allow for room size, and work safely-you should be ok. I'm still researching R134a and flammables blends that Perdue University worked on, which mitigates the risk even further.
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MMT,
Thank you for this very clear and rational analysis of an undeniable problem with R290. Your findings replace 100 pounds of unreasonable fear with 10 pounds of well-thought caution.
I think that anyone who wishes to proceed with R290 must read, and carefully consider your post.
BTW, I still think that a propane sensor that can control a non-arcing evacuating fan should be standard equipment with such a setup. What's good for a boat is good for a basement.
Sincerely,
-AC_Hacker