HAI Omnistat RC80-B compatible with 2-wire heater?

[rickk]

Hi,

I'm contemplating the purchase of an Home Automation International Omnistat RC80-B:
http://www.homeauto.com/Products/Omnistat/rc80.asp

But I'm wondering if it will work with my heater, which only supplies two lines with 24VAC, which will turn on the heater if the contact is closed.

Looking at the manual it seems that in certain configurations it does not need an 24VAC "Common" line, but in others it does. Ofcourse it would be easy to modify the boiler to supply this, but unfortunately this is a rental property so I'd rather not modify the boiler if I can avoid this.

Does anyone have any experience with these thermostats? Or any alternatives to consider? I've found out that the RCS stats will work with my heater, but unfortunately only the X10 version appears to be available in Europe, and I'd rather have serial control, which will be expensive when ordered from the US (import duties + different PSU).

There's ofcourse the Digimax 210 option, but I'd rather control thermostat than the boiler directly from my HA system (easy manual override of the setpoint from the wall unit -> high WAF).

Any ideas or comments are greatly appreciated,
Rick

[Snelvuur]

You should also check the other topics, for example: http://www.domoticaforum.eu/topic.asp?T ... =honeywell

Some of the heaters can be switched, but only allow you to switch it on or of to a certain temperature. I dont see alot that comes out of the box with support to set the temperature remotely too. Although i would expect settings a temperature of 21 degrees and being able to remotely put it on or off would be sufficient for most needs.

// Erik (binkey.nl)

[rickk]

Hi (again) Erik,

Yes, I've checked the other topics on this forum, yet they don't really address the setup that I'm aiming for. I've worked out some solutions that would indeed do what you suggest (switch between setpoint on the thermostat and off/setback temperature), and this is indeed my "plan B".

However, the problems I have with this approach are:
- My girlfriend sometimes like to crank the heat up to "retirement home levels", I don't want to wake up/come home in with the heater on 25 degrees - therefore I'd at least like to be able to reset the setpoint to something reasonable from the HA system
- (Depending on the thermostat & implementation) it's not possible to manually override the "off" setting -> low WAF if the HA system acts up
- My current thermostat is broken, so I'd need to invest in a new 'moddable' thermostat and something like an UM7206 (or maybe even an PIOX15, because I'd really like to be sure of the status of this fairly critical system in my home), this means that cost-wise I already end up at something like 50% of the price for an RC80 - then I'd rather pay double that amount to get 2-way communication and full control.

Hence my interest for the omnistat

Thanks for your answer,
Rick