11h is embarking on a project to use a java based microcontroller (Tini) as a smart thermostat with a zone controlled HVAC system. Each floor vent will be controllable and each room will have it’s own temperature. 1-wire devices from Maxim-ic will be used to collect the temperature and motion sensors from each room and control the servo motors that are attached to the floor vents.
I’d like to throw together some ideas about the zone hvac system before writing a large IPS (Internal Product Specification) or EPS (External Product Specification).
I’ve been thinking about a system that could have a stored HVAC cycle for up to a week.
Since each DS2770 has 40 bytes of memory, each temperature sensor could store its own temperature setting. This way a configuration file or a server would not have to exist to know what the temperature is set to for each sensor; the 1-wire network could be polled to determine what the current temperature setting is for a particular temperature sensor.
User (asking)
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Tini (polling 1-wire network, responding results to User)
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|\_StoredTemp 1 (Living room)
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|\_StoredTemp 2 (Dining room)
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\_ StoredTemp 3 (guest bath)
I took my thermostat apart to see how it works. After many years of debugging discrete logic, simple on/off circuits escape me.
Are you ready for this?
Three wires.
Red, Green, and White.
Red = 24VAC Return
White = Call For Heat
Green = Force Fan On
Red + Green = fan on
Red + White = Heat on (with fan)
Just found a relay for the in wall resistance heaters in B’s house.
Double Pole Double Throw 10 AMP relay that’s 10 AMPS per 120 V…
That won’t work. The 120V is the COIL voltage at 5k-ohms. We need it to switch at 4.5v-5v DC.
Source: Google cached relay datasheet http://66.102.7.104/search?q=cache:48was_OAylMJ:kestparts.com/datasheets/KRLYseries.pdf++site:kestparts.com+KRLY&hl=en
Ah, I totally lost interest in this project as I moved and no longer have a house with forced air. I moved to a house that has wall board heaters with similar thermostats like Brian’s house. However, I discovered that it was just as easy to turn the heat on and off by hand and just shut the doors to every room to trap the heat in the house. Even paying slightly more than $0.09 per kWh for electricity I was able to keep my heating bill less than $190 each month this past winter.
Notice you’ve moved but just as an aside there are many small linux based boxes out there that could handle the job of a smart controller with the appropriate interface