Secure SRT321 (aka Horstmann HRT4-ZW) Thermostat woes

I've got one of these with the boiler relay module too.

It was an absolute git to get working and I've only managed to pair the thermostat, not the relay - the thermostat is paired to the relay and my HE controls the thermo stat.

So first question, how can I pair the relay? I read something about when the two components are used on their own the thermostat is a hub?

Next dumb question...

I'm using this driver "SRT321 Thermostat by MeavyDev - Converted for Hubitat by Scruffy-SJB"

It sort of works but am having some issues....

Its sending a LOT of logs... I don't really understand the concept of wake time interval with zwave devices. I thought that would limit the amount of communications? Doesn't seem to:

The Wakeup interval report seems to be as per the settings, ie 10 minutes but it does report beyond that. In between its reporting temperatures and heating states too.

What is a Zwave wake up used for?

Anyway, at the rate its going I doubt the battery will last a month.

Must be something I'm doing wrong.

Thanks for reading an idiots ramblings :slight_smile:

The SRT321 will send data when the temperature changes, setpoint is changed by the dial or when the operating mode changes (which in theory should always be in conjunction with a temperature or setpoint change).

Outside of that it won't communicate at all until a wakeup happens. So if you change the setpoint in HE the SRT321 won't know anything about it until it wakes up and communicates with HE.

I have added a parameter into the driver "Report Temperature Threshold" so that you can set the temperature change reporting. I see in your log that the setpoint is 20C and your temperature is 19.9C - so the SRT321 seems to be flipping between calling for heat and then going idle and then calling for heat again. I've also commented out those debug statements in the driver.

The updated driver will be in HPM shortly.

Which relay are you using?

I hope this helps.

Thanks, Simon (aka scruffy-sjb)

1 Like

Thanks Simon!

Can't remember how I installed your driver before - looking at my HPM its not showing on check for updates, so i must have installed it by hand. Do I just remove the manually inserted driver and re-install via HPM?

The relay is the matching SSR303 / ASR-ZW.

I think I've just found an article on how to pair it - suspect another few hours of cursing like last time... APNT-20 - Configuring the Secure Thermostat and Receiver — Vesternet



Maybe I have something up with my HPM registration..... I find the whole github "Pull Request" thing really confusing.

I just checked -> In HPM search by keyword for SRT321 and you should see my driver.

If you want to get it manually it lives at -> Hubitat_HPM/SRT321 at main · scruffy-sjb/Hubitat_HPM · GitHub

I've uploaded my SSR303 Driver to -> Hubitat_HPM/SSR303 at main · scruffy-sjb/Hubitat_HPM · GitHub

The SSR303 is not in HPM yet.

1 Like

Thanks Simon!!!

@simon do you have these SRT's yourself?

Do they eat batteries?

I've only had mine a few weeks and the battery is sub 10% already :-/

I have 11 of them in rooms. 2 to 3 month lifetime on batteries. When the battery does die they do seem to go from battery ok to 1% very quickly.

I have 3 SSR303's - 2 heating zones and a hot water zone.

All these devices (except 1 SRT) are older devices - that 1 SRT is Z-Wave Plus.

I have an app that I wrote for myself that knocks the SSR's on/off based on the SRT's. The SRT's themselves are managed by the built-in HE Thermostat Scheduler.

When the new Shelly wall tablet (switch size) comes out shortly I'm going to get one and play with it and see if it's a viable replacement. It does not need a neutral line, so can be powered with a live wire only.... I can a few places where this may work.

How are you working that?

I've been thinking how best to do multi temp sensors to control a heating zone but can't get my head around the logic.

Got any tips?

I wrote an app - I can share it with you, but you will need to modify it for your usage.

The main bit that you probably will not need is I fire off RM rules whenever a thermostat calls for heat or longer required heat - these rules turn on or off radiator valves in the room that the thermostat is in.


1 Like

Thanks Simon - I'll have a play with that when i get five minutes :slight_smile: