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HVAC Zone Controls & Zoning Dampers

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More unbiased Zone control discusson on homeenergy

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QUESSTION by
Adam Zielinski

Homeowners with forced air duct systems always want to close the registers in rooms they aren't using, and close the doors to those rooms, in the belief that doing so will save energy and money.
I always thought doing this was over-rated and unlikely to save a significant amount of energy or money.  I could see doing it for one or two rooms perhaps, but sometimes homeowners close off half of their house or more.
This creates unbalanced air flow in the duct system and likely results in over heating the furnace heat exchanger, and or short cycling the furnace.  So the furnace spends a lot of time in start up mode and less time at peak efficiency.
I have not seen any real studies done on this however.  I'd like to see some data or research on this.

Reply by dale conner
Adam, most furnaces will move the proper amount of air through the blower and heat exchanger if the furnace cabinet pressure doesnt exceed .5 IWC and the furnace capacity was chosen based on a manual J calculation. This information can be found in the furnace installation manual or IOM (installation,operation,maintenance) that comes with a new furnace. However, this does not mean we are getting adequate air delivery to all of the rooms in the house due to excessive air leakage in the ducts and/or incorrect duct lengths or diameters routed to each room.

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QUESTION by Judi Lyall

How about using a motorized damper ?

Reply by dale conner
A single motorized damper can be used to control a zoned area but you also have to install a barometric by-pass damper to prevent over pressurization
www.zoningsupply.com

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See full discussion: http://homeenergypros.lbl.gov/group/hvac/forum/topic/show?id=6069565%3ATopic%3A7207

Retro thermostat... 1982 Electronics Guide review of Magic-Stat

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magic-stat.jpg

Published in Playboy's Electronic Entertainment guide in Fall 1982. 

This is off of our normal subject but I came across this old magazine that includes other articles like "There's more to life than Pac-Man: How to beat Donkey Kong" and "What computers can do for you" which says that "VisiCalc is the most popular program of all time with 250,000 copies sold".  And it included a scathing review of this Magic-Stat product.  Sold for $79 mail order.  At first glance, I thought it was just another ugly thermostats in a long history that still goes on today.  Then i read the article which explains a "LEARN" mode that makes it easier to set much like the nest would do decades later.  Also, it claims to have what is now reffered to as "adaptive recovery".  This is where the thermostat starts the equipment before the set time so it can get the home to temperature at a specified time instead of just starting to get to temperature at the time of setpoint.  I haven't done any fact-checking, but it says they are the first thermostat to do this... too bad it took 20 years for this to become a more standard feature.

Here are a few more pics I took of the magazine...i claim no rights or ownership of any of this material.