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Joined: January 13 2011
Location: United States
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Posted: January 13 2011 at 11:58 | IP Logged Quote learmud


I'm trying to find out if what I would like to do is
doable or being done by others. I haven't bought the
software yet, i'd like to make sure I can do the things I
am interested in first. I would like to first setup a
system that can monitor my wood furnace temperature (that
runs 24/7) then control the motorized damper for better
efficiency. Can I use high temp sensors over 300+?

Then id like to expand into some of the other things such
as controlling and monitoring zones, lights and things.

I just bought a a passive solar, Geo thermal cooling
(tubes), and solar water heater house from the 80's in
New England. If you have any suggestions please let me


Edited by learmud - January 13 2011 at 13:51
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Joined: July 28 2007
Location: Canada
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Posted: January 20 2011 at 21:33 | IP Logged Quote spou

Hi learmud and welcome to the board.

I've been playing with temp sensors for quite a while, and for sure that your wood furnance will require more than the usual.

For the usual, a simple Dallas DS1820 will be enough. I have 12 of those around the house and outside. With a small search, you will find a tread that explain how to do it and imoprt the readings into powerhome. It's cheap and easy.

For higher temperatures (75C or more), you need a thermocouple. Those device generate electric signal(very small amount, in the milli-volts!) in a way that can relate to the temperature. A thermocouple "converter" is needed to translate that analog current amount into a digial number. Depending on the type of thermocouple (5 differents types, depending of the temperature range and other factors) you can mesure from 200C to 1500C (well, you can mesure less too, but the troubles is needed mostly for high temperature)

see Omega web site for details:

The same Omega document also shows how to hook a DS2760 device with a few simple parts so you can use the DS2760 as a regular temperature probe that LogTemp (my favorite software) can read. If you feel that handling a soldering iron can cause major burns, sells a DS2670 fully assembled and ready to use (for 30$), you also need the themocouple itself (about 20 box)

I have a very high WAF with the sensors.

For serious metering (geothermal and solar heathing), prepare to dig in your pocket more that you think, even for simply metering flow of liquid for the geothermal (think about 75-100$ here) My guess is to add one item after the other so it shows less on your credit card. :-)

Now, the second part of your post concerns output from powerhome to dampers and other devices. On that part, I can not help you much, because each "actuator" is differents: proportional with voltage or PWM, full on/off, cycling on/off. Some works on 12, 24 even 48 volts.

for what it's worth, I've got some air dampers actuated with a RC servo (PWM) via a serial interface.

In your case, think failsafe in case the computer froze at the wrong time, or in case a sensor turns stupid.

I hope it helps you to take a better decison. One thing for sure is that Powerhome is very very flexible. What it can't do by itself can be programmed in various scripting languages, so sky's really the limit here.

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Joined: January 13 2011
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Posted: January 20 2011 at 22:15 | IP Logged Quote learmud

Some good info, thank you!
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