SRT321 Room Thermostat function - just not getting it

Hi guys,
I’ve sucessfully got the SRT321 room stat hooked up to my vera lite, it shows the current temperature the words ‘Off’ and ‘Heat’ and the set point temp control in red (as shown in the attached image). I’ve read in [url=,14646.msg112113.html#msg112113],14646.msg112113.html#msg112113[/url] how to associate it with a relay switch (not tried that yet) but don’t understand how how the thermostat functions. When I bought it, I thought it would behave like a switch, i.e when the actual temp falls below the set point it would close a (z-wave) switch so as I could act upon it, but obviously I’m missing something.

Could someone give me a helping hand please on how to use is/point me in the right direction, as I want to make more use of it other than a very pretty paper weight.
I’m guessing that after a lot of studying I’ll be able to write some scenes to schedule the heating to come on and add some LUUP code to poll the room stat to control the boiler / zone valves, but before I head off in (possibly) the wrong direction if someone could tell me how they control their heating, that would be great.
Many thanks,


The SRT321 is a room thermostat, it does not include an internal relay or switch (regardless of what the VERA icon suggests).

It needs to be used with a Z-Wave relay such as the Secure Boiler receiver (SSR303) or a normal relay such as a Fibaro. The relay will then control the boiler or heat source you wish to control.

More information on how to get it working in VERA is available at

There is also a guide to using it with VERA scenes -

As you will see in these, VERA uses a generic icon for this device (and the SSR303). The thermostat does not have a switch so the On/Off buttons on the icon are misleading as they don’t do anything.

Hope this helps.


Hi Mark,
thanks for the fast reply, as I bought the SRT321 from Vesternet I should have had the gumption to check on their resource notes first, the tutorial is a great help.

I have the Fibaro relay modules controlling the following zone valves, which in turn spark up the boiler: Hot Water, Central Heating, Kitchen UFH and bathroom UFH. There’s also a Fibaro relay module in the boiler room to control the hot water secondary recirc pump. I guess I need to sit down and write a schedule for each.

I still can’t get my head around why I need to associate the thermostat with the relay when there is another factor (time of day/day of week schedule) to consider before the heating is turned on/off but I’m sure this will become aparent as I go through the tutorial.

Many thanks,
Philip Butler

After reading a few posts on this forum, I ventured to install Program Logic Event Generator (PLEG) which was a learing curve as I’d not installed an app before! Within 10 minutes I had the room stat controlling a desk lamp that was hooked up to Z-wave (ambient temp lower than set point = lamp on, ambient higher than set point = lamp off) A very basic control that needs improvement (need to add some hysteresis to prevent frequent cycling of the boiler) but it’s got me heading in the right direction. From a learning aspect I now need to figure out how to do the same in LUUP.

Funny you should say that.

I tested PLEG and Day/Night last night as well. I got a couple scene working quite nicely.

I think PLEG has a lot of potential, you shouldn’t need to resort to LUA.

I’m going to have a more detailed look into it and then I’ll put some blog posts and application note together around it (linking backto Richard’s site).