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Author Topic: How to Control HVAC with Vera and one wire sensors  (Read 4895 times)

Offline scubaguyjohn

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How to Control HVAC with Vera and one wire sensors
« on: January 04, 2012, 09:47:43 am »
Presently, I use Homeseer pro for home automation with a mix of Zwave and insteon devices..  Homeseer is unsatisfactory with its 1980's GUI and always on PC requirement.  I'm looking to switch to Vera3 to add HVAC control and to control all existing devices.   

I have 5 heating zones and only have 2 wires run to thermostats.  Rather than attempt to run additional wires to power Z-wave thermostats (which i understand work much more reliably than battery powered versions), I want to take advantage of the many cat 6 wires throughout the home.

My thought is to connect one wire temp. sensors to the cat 6 wires and then use a relay to turn on/off the 24 volt heating zones at the control panel.  Essentially, Vera would operate as a master thermostat.

My questions are:

1.  For a  temp. sensor, would something like this work:  EDS OW-ENV-TH - Temperature / Humidity Sensor or  EDS  STP010 - 10' General Purpose Temperature Probe  (sorry, i can't post links)

2.  Would I then connect the one wire servers to a:  EDS OW-SERVER - 1-Wire to Ethernet Server

3.  How does the ow internet server interface with Vera from a software perspective?  Does it show up as a device with multiple children that can be polled to base events (heat on/off) on the current values of the sensors?

4.  How would Vera control the 24 volt relays to turn on the individual heating zones?

5.  Has anyone implemented a system like this and how is the reliability?  Clearly, relying on Vera to control all the heating is a bit of a gamble but it would give me a ton more programming flexibility vs a traditional, rather dumb thermostat. 

Feel free to shoot holes in my plan/theory as i know nothing about the Vera world.

thanks in advance, John.

Offline myk

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Re: How to Control HVAC with Vera and one wire sensors
« Reply #1 on: January 04, 2012, 01:25:44 pm »
I personally wouldn't trust the Vera2 _as_ my thermostat, however I do use it to control two thermostats I have already (change the setpoints on a schedule)

If money wasn't an object - first option is to just have the damn thermostats wired in each zone (Z-Wave thermostats hopefully =)  )

That being said I've lived in houses where no hourly rate could have you end up with an electrician doing a particular job without making a mess of the walls so that being the case:

The RCS TZ45 (or TZ40 I believe) http://www.smarthomeusa.com/ShopByManufacturer/RCS/Item/TZ45/ has the option for a remote (2 wire) temperature sensor http://www.smarthomeusa.com/ShopByManufacturer/RCS/Item/RS15/ which you can use to override the internal temp within the thermostat.

So you could hook up a bank of those in the basement hooked up to the zone control panel - and use the 2 wire sensors in each room


Another option would be to get a 24V-AC adapter for each room and run that to C(common) on whatever thermostats you get.

I have the 2GIG CT30's around my house and batteries were lasting about 3 months until I finally wired the suckers in (at the furnace)

Offline nickrwym

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Re: How to Control HVAC with Vera and one wire sensors
« Reply #2 on: January 04, 2012, 02:07:06 pm »
5.  Has anyone implemented a system like this and how is the reliability?  Clearly, relying on Vera to control all the heating is a bit of a gamble but it would give me a ton more programming flexibility vs a traditional, rather dumb thermostat. 

Feel free to shoot holes in my plan/theory as i know nothing about the Vera world.

thanks in advance, John.

Hi

I have done something very similar using Vera 2 and it's been running for a couple of months with only one glitch that needed a Vera reboot. I'm in the house that it's in so can keep an eye on it, if it was a rental or holiday home I would put some form of mechanical backup thermostat in.

In my case I am using an appliance switch to operate a mains operated relay and the contacts of that control the thermostat input to the heat pump.

Some simple Lua code decides whether the temperature reading on the one wire to ethernet converter is above or below the required level or in my deadband.

I have DataMine running recording energy used, switch status, inside temperature and outside temperature.

It works well, heating control is close, I have different temperatures set for different times of day, there is a motion sensor controlling the heating during the day so if the house is unoccupied then temperature can drop.

I also have different target temperatures set depending on the outdoor temperature, it seems to work best to set the inside temperature a little higher when it's warmer out.

If you want any more info feel free to ask

Nick