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I have been working with Tobin on a design combining domestic heating and domestic hot water (DHW) using an instant hot water heater, solar and a wood stove as sources and under-slab radiant and baseboard as emitters. It is for his house in Portland. Here is where we were at a couple of weeks ago. Now we tune the system to available components.
An ever-increasing percentage of future hydronics systems will operate at water temperatures of 120 degrees F or less under design load conditions. This is especially true if these systems include renewable energy heat sources. Optimizing energy efficiency is now the motivation for low water temperatures. New heat emitters as well as classic low-temperature radiant panels are the enabling technology. I urge everyone in the North American hydronics industry to embrace low-temperature hydronics and tool up to deliver solutions that ensure its implementation. -John Siegenthaler
space heating design
A low temperature ‘junk heat’ system designed to meet the design temperature load of 25,000 Btu/hr. Most of the space heating is provided by radiant floor heating, most of that through a high thermal mass radiant slab with water at ~100 °. The remainder is provided by panel radiators designed to operate at 120 °. The radiant floor water is drawn from the middle of the 119 gallon storage tank. The panel radiators draw their water from the top of the tank.
A evacuated tube solar panel takes water from the bottom of the tank and returns it to the upper region of the tank. The water in the tanks is at atmospheric pressure. The tank is used for heat storage and as the drainback tank for the solar collector. The level can be determined through the sight glass and is maintained by the user.
The intent is to maintain stratification of temperature within the tank
Additional heat for the storage stank is provided through heat exchange from the DHW system.
Most Likely to Succeed NEW YORKER December 15, 2008 Annals of Education
I feel affirmed by the research. For the 20 some years my 3 boys were in the Boston Public Schools and my modis operandi on school choice was: “Teacher effects dwarf school effects: your child is actually better off in a “bad” school with an excellent teacher than in an excellent school with a bad teacher.” I continue to believe this is true.
Gladwell uses the metaphor of scouting a quarterback to illuminate the difficulties in selecting good candidates for teaching jobs. “A group of researchers—Thomas J. Kane, an economist at Harvard’s school of education; Douglas Staiger, an economist at Dartmouth; and Robert Gordon, a policy analyst at the Center for American Progress—have investigated whether it helps to have a teacher who has earned a teaching certification or a master’s degree. .. neither makes a difference in the classroom. Test scores, graduate degrees, and certifications—as much as they appear related to teaching prowess—turn out to be about as useful in predicting success as having a quarterback throw footballs into a bunch of garbage cans.” Once again there is evidence that the ed schools aren’t all that effective or relevant.
I’d like to have a boss like Bob Pianta, the dean of the University of Virginia’s Curry School of Education. He seems to be the kind of person who could engage his staff in continual research. I need somebody on my side who is interested in studying what works by direct observation and research. One thing he found is that good teachers have a “‘regard for student perspective’; that is, a teacher’s knack for allowing students some flexibility in how they become engaged in the classroom.” Another thing he notices in videos of the classroom is that “feedback, a direct, personal response by a teacher to a specific statement by a student—seems to be most closely linked to academic success”.
Alas Gladwell concludes like so many others with a non sequitor regarding merit pay. “If we find eighty-fifth-percentile teachers who can teach a year and a half’s material in one year, we’re going to have to pay them a lot—both because we want them to stay and because the only way to get people to try out for what will suddenly be a high-risk profession is to offer those who survive the winnowing a healthy reward.” Neither reason seems true by my experience. Maybe it would be high-risk for ed school grads who can’t “drive the offense” but not really for people who developed the “knack”. As for “paying them a lot” it sounds like the usual doublespeak by the reformers who want to privatize schools and reduce union pay and benefits while talking about merit pay for the few. I don’t buy it. Surviving the incompetence of the winnowers is the real challenge.
The header picture is from Cameroon, near Bamenda. Natalie was with us, you can see the top of her head to the right of Peri. She and Ari taught in the Amercan School of Douala from 2006-2008. Tobin, Noah Peri and I visited for Christmas break in 2007.
We were invited to a wedding in