Puron

Well, both Puron (R410A) and R22 are heavier than air, and I'm pretty sure are both basically odorless. The link you posted gives a toxicity rating of A with a PEL greater than 400 ppm. That's a permissible exposure limit greater than 400 parts per million, and I believe A is the least toxic rating. It also lists 1000 ppm (which is 0.1% or a LOT since air is only about 0.04% carbon dioxide) as the long term pel, 8 hrs/day, 40 hrs/week, which is what you should think about if you are sleeping in it. Anyway, do a web search for ashrae toxicity ratings to get their definitions.

-- Regards, Carl Ijames carl.ijames at verizon.net

Ex. But what's the question? ;-)

Short answer: I really wouldn't worry about it too much. Fluorocarbon refrigerants are (mostly) harmless ;-) (SIC - RIP DEA) and non flammable.

Big leaks that would dump the whole charge in a matter of minutes are really /really/ rare if the HVAC system was installed right - they didn't leave the lineset where it can rub through on a sharp edge, or leave long sections of copper lineset tubing unsupported where it can vibrate and stress crack. A home system doesn't have enough refrigerant in it to displace all the air in a bedroom unless it all dumps at once, and you'd hear that. And installing a permanent leak detector alarm system will cost you a WHOLE LOT of money.

But if you really want peace of mind, the Ritchie "Yellow Jacket" #68002 Fixed Leak Monitor

would be the unit, it is made for permanent installation in commercial refrigeration equipment rooms (like supermarkets) where a big leak on a large system with 25 to a few hundred pounds of refrigerant inside could displace enough air to make it dangerous. They will sound off at

100 PPM of CFC HCFC or HFC refrigerants in the air - but they are $500 wholesale, meaning you pay a bit more for markup if you don't have an 'in' at a refrigeration supply house.

(Johnstone Supply H25-885 $486.72 in the last catalog. Subject to change if their costs change significantly.)

Specific gravity of R134a vapor in air is 3.25, meaning it should sink like a rock. If you install the alarm, put the sensor low.

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the freon that was developed to cool a/c units is not poisonous... the old amonia systems will kill you.... if any gas fills up the area you are sleeping in and displaces the oxygen then you gonna die anyway.... be it puron, R-12, R-22, R-134 or any other gas..... but its pretty safe to have in a home a/c heat pump system....