House Freeze Alarm / Furnace Failure Alarm / Pipe Freeze Alert

This is another feature that can be added to an Insteon / Universal Devices ISY994i system - a freeze alert to warn of a furnace failure, to prevent pipes freezing or other damage in cold weather. I negotiated an insurance rebate with this capability added to my system, so it's worth considering and looking into.

I had some unused inputs on an EZIO2x4 Input Output module, and was looking for a simple way to add a freeze alarm. I also had an unused Honeywell CT3500 digital thermostat, with single stage heating and cooling functions. This was very quick and simple to set up, starting with the installation of the thermostat next to my automation panel in my mechanical room in the basement. The Honeywell CT3500 runs off battery power - and the internal relays are switched on battery power as well - so you don't need to provide the thermostat with 24VAC to provide the dry contact capability.

Install the digital thermostat at a convenient location. Note the wiring connections - R and W connections give you a dry contact output for the heating activation of the Thermostat.

With the thermostat installed, and a dry contact wire pair connected to the R and W (Heat) terminals - it was time to install the thermostat face, and program the thermostat. I programmed the thermostat so that it would always return to the programmed temperature setting if anyone (kids) play with the setpoint keys on the face of the thermostat. The CT3500 can be set as low as 4.5 degrees C - but in my case I decided to give myself a bit more warning and programmed the heat setting on the thermostat to 7 degrees C. 

CT3500 thermostat programmed to provide heat at 7 degreex C - Label added to face of thermostat indicating function of the thermostat and a reminder to replace the batteries once a year. 

On the automation side, you have to have an input contact interface to your Insteon network. You could use a Smarthome IOLink, an EZIO module from Smartenit with input capability - the EZIO2x4, the EZIO6I, or the EZIO8SA. In my case, I had free inputs on an EZIO2x4 2 Relay 4 Input Insteon module.

The EZIO2x4 has four inputs per device - 2 inputs are dry contacts, and 2 inputs are digital / analog inputs that need to be configured for your application. Since my dry contact inputs were already being used for smoke detector and alarm interfaces - I had to use one of the digital inputs for this function.

The instructions for the EZIO2x4 advise you to use a pull up resister in order to convert a digital input to a dry contact input. Some research on the Smartenit forums provided some additional detail - you should use a 6000 to 10000 ohm resistor - connected between the 5V and the I3 or I4 terminals - in order to avoid drawing too much current from the 5V terminal. Then - your dry contact connects between the common terminal and the I3 or I4 terminal. Here's what the connection looks like with the pull up resistor:

Using a pullup resistor to protect the 5V terminal on the EZIO2x4 from overcurrent, when using inputs 3 or 4 as dry contact inputs.

On other thing I learned on the forums - that if you are not using the digital inputs on these EZIO modules - you should ground the input to keep them from floating, and initiating unneeded Insteon traffic on your network. If you look at the photo above, that's what the green wire is used for - shorting the I4 input to the common terminal. 

Once the thermostat has been programmed, it's time to program your ISY-994i. I set up a new notification message - House Freeze Alert - and created a new program to check the status of the I3 input on this EZIO2x4. Whenever the input changes to "On" that indicates that the thermostat has called for heat - indicating a temperature inside the house of less than 7 degrees Celcius. In that case - I have the ISY-994i send me an email to my email address, and a text message to my phone with the Freeze alert message. 

You could also tie this functionality to a monitored home alarm system - simply by using one of the output contacts on the EZIO2x4 to trigger a zone on your home alarm. Your alarm company could configure this zone to warn of the house freezing - and initiate a call out.