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The majority of heating systems in the US use ducted hot air distribution, and all hydronic systems combined comprise at most half of the rest. Most estimates put all hydronic systems (not counting steam) combined at between 3-7% of all heating systems (trending downward over the past decades) with radiant floors being a small fraction of that.
The so called "L" disease was discovered in ducted hot air systems, and i still feel "sick" house syndrome when I spend time in older ducted homes. Take a look at the crap in the old pipes, you'll never duct anything again. I started out stupid, all caps, removing asbestos wrapped pipes in basements of midwest homes for my uncle, and no one ever heard of a mask then. coughed up black crap all night. Probably heading for the asbestos lawsuit sleazebags soon, although my uncle in his 80's is still healthy.
I heat one house electrically, open radiant, and when at rest it sits at 150'f, so i suppose that jolt give the germs a pause. But when circulating, the temp of course falls near 120 and 115. Maybe I'll drop a pile of my silver dimes into the heater next time I open it. Or hang them on the anode.
But all in all, I think we are on a witch hunt that may lead to another round of regs that finish off housing altogether. But where are all the dead people with appropriately names "swamp" coolers? ever live in a swamp?
Runs with bison
Let me explain it to you: they (corporate geniuses who now run our tax policies and have done such a great job of zero f'ing growth over the last decade while blowing a huge hole in our budgets) gave away all of our manufacturing tech to the Chinese a decade ago. We (as ordered by our conservative corporate masters) were teaching them how to make things using tech they didn't yet have. Their govt. is way smarter than ours and light years ahead of our idiotically selfish and short-sighted corporate bozos. They think Sun Tzu, our guys are more like Yosemite Sam. The Chinese insisted that to sell into their markets we: 1. Had to build the plant there (not in neighboring countries either...killed some of our projects.) 2. Had to staff it (including engineers, supv. etc.) with Chinese. 3. They had 51% ownership. 4. We gave them the tech. 5. Their design institutes built the equipment. 6. We had to teach the design institutes the basic so that they could do step 5 (they were f'ing clueless, because they had no experience with stuff that was industry standard to us.)
Look, I agree completely with the corporate greed, lack of guard of our knowledge base, and base stupidity of selling and giving away our hard won MFG. systems. But we started with the JAPANESE, to "rebuild" them - screw them, let them eat cake. Then the Marshall plan that gave Germany the machines to sell parts to Iran and Pakistan to build the bomb.
Then we PAID the Russians for their nuclear clean up, the richest and poorest nation all rolled up in one.
The bean counters at the big industries that sold our knowledge to the chinese should be strung up by the nuts. But in their defense, if we had not, the germans or italians or french would have done it anyway.
And we build schools in Afassisthan, while being shot at. Here at home our teachers are on food stamps and havent had a job in years. And i know many teachers, and 2/3rds of them could'nt find their way out of a paper bag. And all the metal and wood shops went away because baby johnny might cut his finger. What the hell good is knowledge of kicking a ball around a field to a 25 year old unemployed dope?
On the upside, industry REALLY is coming home, and even the japs are starting to rethink that little rock they sit on, ready to fall under water. Honda is moving most production here. BMW EXPORTS from the USA.
And the USA still beats all hands down for manufacturing output and capacity. The next time that moron that runs Iran gives a speech, rather than throw a shoe, lets put a cruise missile up his navel.