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Furnace Fan - Run 10 minutes out of every hour

Posted: Mon Sep 10, 2012 7:07 pm
by jtcweb
To help move air around my house I would like the furnace fan to run at least 10 minutes out of every hour, or maybe more. I also have a heat exchange ventilator that I want to program times for it to run.

Hardware - I want to tie to the GPIO pins:
For the heat exchange ventilator I just need to be able to turn it on and off based on a schedule I pick i.e. on for one hour off for one hour. Therefore I assume some kind of relay could be used. I'll have to check on the current draw, but all there is to is power wise it two fans, one blowing out and one blowing in.

For the furnace fan I need to sense when it turns off and start counting. When the number of minutes I specify elapse without the thermostat turning it on, I want to turn it on with the RasPi for a set number of minutes and then reset.

Software:
I have no idea, somebody help me. I would start out with some kind of script running in the background and then move to some kind of web interface. If there is a home automation package out there that would do this then I would be open to trying it.

Re: Furnace Fan - Run 10 minutes out of every hour

Posted: Mon Sep 10, 2012 7:46 pm
by morphy_richards
For the purposes you are describing I personally wouldn’t consider using a raspberry pi.

You could use an arduino - it would be a bit cheaper and easier to carry out the project as the control software to do what you want is an integral part of an arduino. This instructable might help you carry out what you are trying to do.

If you wanted to make a "smart" or even "intelligent" furnace fan controller, rather than one based on timing, then I think that is where a raspberry pi would be more appropriate.

Re: Furnace Fan - Run 10 minutes out of every hour

Posted: Tue Sep 11, 2012 9:39 pm
by jtcweb
My future plan is to have more sensors and do data logging, thus my desire to use the RasPi

Re: Furnace Fan - Run 10 minutes out of every hour

Posted: Thu Sep 13, 2012 8:11 am
by bcatalin
It is very simple. I've done a similar project for my irrigation system.

You need a relay board Image


with 1,2,3,4 relays depending on your needs. Connect the relay board to the GPIO/5V/GND.

Write an C application to set on/off your desired GPIO, and an application to check the status for GPIO.

Write a php file to be able to create a cron file with your timings and lunch the cron with your cronfile.
Write other php file to be able to check the status, calling the status program.

Re: Furnace Fan - Run 10 minutes out of every hour

Posted: Mon Sep 17, 2012 5:11 pm
by jtcweb
Do you have a source for a relay board?

Re: Furnace Fan - Run 10 minutes out of every hour

Posted: Mon Sep 17, 2012 10:03 pm
by pinkstond
I have purchased a few of these and have been playing with them:

http://www.amazon.com/gp/product/B0057OC5WK

They work great for me. They also have 4 channel and 16 channel variations of this floating around.

Re: Furnace Fan - Run 10 minutes out of every hour

Posted: Fri Oct 05, 2012 2:48 pm
by rooster
jtcweb wrote:To help move air around my house I would like the furnace fan to run at least 10 minutes out of every hour, or maybe more. I also have a heat exchange ventilator that I want to program times for it to run.

Hardware - I want to tie to the GPIO pins:
For the heat exchange ventilator I just need to be able to turn it on and off based on a schedule I pick i.e. on for one hour off for one hour. Therefore I assume some kind of relay could be used. I'll have to check on the current draw, but all there is to is power wise it two fans, one blowing out and one blowing in.

For the furnace fan I need to sense when it turns off and start counting. When the number of minutes I specify elapse without the thermostat turning it on, I want to turn it on with the RasPi for a set number of minutes and then reset.

Software:
I have no idea, somebody help me. I would start out with some kind of script running in the background and then move to some kind of web interface. If there is a home automation package out there that would do this then I would be open to trying it.
I have something similar controlling my central heating.

GPIO can control a relay through which the central heating runs.

the gpio pins can just be written using a simple command on the command line

I use a web interface using php which writes the GPIO command to a file and a cronjob wakes up every minute to run that file