Guest Posted June 8, 2012 Posted June 8, 2012 Good day... I would like to add a few Insteon compatible thermostats to my home. I currently have hot water baseboard heating system where only 2 wires go to each thermostat (dry contact battery powered t'stat)...that would be 1 wire 24VAC up to t'stat and back down second wire to energize zone solenoid. That being said, every thermostat I've looked at requires "power"from the HVAC circuit which leaves me short a wire. From what investigation I've done on the Venstar "Add-A-Wire" accessory, I don't think that will work as all 3 wires would need to carry 24VAC. Does anyone know of a "dry contact" Insteon compatible thermostat (probably battery powered) which I could use? Please also correct me if i have made any incorrect assumptions or statements. Cheers....Your comments are greatly appreciated PLCG
Xathros Posted June 8, 2012 Posted June 8, 2012 PLCG- I ran into the exact same issue with my setup although mine is a single zone forced hot air system. I tried to find a way to just do a 3 wire run from the furnace to the Venstar but couldn't find a way to get the necessary connections at the furnace. I ended up buying a 24VAC transformer, pulling a run of 3 wire tstat wire to the tstat location and building a small relay circuit at the furnace to interface to the 2 wire line from the furnace. As I recall, I cost me all of about $20 for the wire and components from Radio Shack and another $20 for the transformer and jbox to mount that to. This has to be a fairly common problem and I'm surprised that nobody sells a conversion kit like this already built. If they do, I was unable to search it out. -Xathros
Guest Posted June 8, 2012 Posted June 8, 2012 That sucks...no way I'm gonna run additional conductors to numerous locations....new home / buried wiring. I don't understand why there is no product supporting what has to be a very common arrangement for hot water / forced air systems. I'll keep thinking and looking.... PLCG
Xathros Posted June 8, 2012 Posted June 8, 2012 There is another configuration that I had considered and rejected. Run the 24V over the existing 2 wire to the Venstar. Add EZIO or IOLinc at the furnace/zone valve/pump whatever for the contact closure and use the ISY to Monitor the tstat and control the zone. Only reason I rejected this is in the event of a comm failure a zone could be left on or fail to turn on. A periodic query could fix that issue as lons as comm failurs are rare in your setup. I preferred to have the tstat do the control directly. -Xathros
Guest Posted June 8, 2012 Posted June 8, 2012 I thought about that approach a while ago....not a big fan. Long story short I ultimately want to control my heat pump system, with what I am sure will have to be thru iTech WiFi/IR. The t'stat hooked to my hot water system would stand as my "backup hot water" heat control and also feed temperature to my controller for the heat pump system control logic (temp setpoint up/dn/on/off etc). PLCG
Brian H Posted June 8, 2012 Posted June 8, 2012 How about the Venstar Two Wire Heat Only Kit? http://www.smarthome.com/30418/Thermost ... 436/p.aspx Not sure if you want to deal with a 24 volt wall wart, but it is for a two wire heat only control.
Guest Posted June 8, 2012 Posted June 8, 2012 Very interesting. Looks like a fella could build one of those with a 24VAC transformer and a small relay with 24VAC coil. Thanks for the suggestion...I'll think about that type of approach PLCG
Recommended Posts