Seems not all manuals indicate this … and I’m looking for a thermostat for a project that controls a cold fermentation room.
I would like to be able to set the temp as low as 35F , but several thermostats I have seen bottom out at 50F
Anybody using a model that allows for some pretty cold set points?
Or alternately a set point of say 50F , but able to program a large offset or calibration so that the set of 50F is really using a temp sensor input of 35?
Also … the required model has to have a remote temp sense capability. Not necessarily wireless, but something away from the unit itself .
Any ideas a good model to research further? maybe a commercial unit?
With PLEG you can turn the thermostat from off to auto when the thermostat changes above/below your set point. I would use. At 1 or 2 degrees of hysteresis in the logic.
[quote=“RichardTSchaefer, post:2, topic:189030”]You can use any thermostat an PLEG.
With PLEG you can turn the thermostat from off to auto when the thermostat changes above/below your set point. I would use. At 1 or 2 degrees of hysteresis in the logic.[/quote]
Thanks for the feedback, but maybe I wasn’t clear enough or don’t fully understand PLEG.
The logic you presented above is exactly what the thermostat does in Auto isn’t it? Why do I need PLEG?
If I turn the thermostat to Auto it will seek to bring the temperature to the set point and I assume the set point is not arbitrary - isn’t it limited to a range that the HW (thermostat) supports?
i.e. Some manuals say minimum is 50F , are you suggesting with PLEG I could set the thermostat to say 40F and it would seek to achieve that?
So what I am looking for is a thermostat that can be set to 35F with PLEG or at the console if those values are actually different. Also needs to have remote sense .
You can use any temperature sensor … even the one in the thermostat that has a limit of 50.
Most can adequately read the temp below 50 deg … they just do not allow setting a temp below 50.
Why not use something built for this purpose like this one? It would likely be cheaper in the long run and definitely more accurate than anything hacked together
Correct. I would not trust whatever process you need to run in a temperature controlled environment to a system cobbled together from parts not designed for this application and then managed by Vera. There are many products like the one a link was provided for above that are specifically designed for this purpose, and will be far more accurate and (more importantly) far more reliable.
Hi Guys - thanks for the feedback to a Vera newbie.
Let me clarify a few things - like w.r.t. the Johnson controller … I already made something similar to this with a digital control that works great … problem is it is not remotely settable. I can monitor the temp via Vera and a sensor while I’m away, but can’t change the set point and this is a functionality I am trying to add.
Secondly, to avoid Vera being the closed loop … and potential failure of that loop … I have an idea for a closed loop thermostat where Vera only Sets or Reads the values - the logic of turning on/off cooling is done by a real thermostat.
My brief idea
Build a wall receptacle into a project box which is controlled by the outputs of a dedicated thermostat for this project
Use the 24VAC outputs from the thermostat (hot, cool, fan, etc. depending on needs) to control a relay that is normally open and in series with the hot side of the wired receptacle
this means the receptacle has no hot side connected until the desired signal from thermostat is output to close the relay
it’s a simple circuit to build and wire for <$25 (or maybe another $10 if you need the 24V/120V transformer)
Benefit of this system is you can read/program your thermostat remotely , but if you have a loss of internet, system hang, etc. your load would still be controlled by the thermostat w/o Vera being required at all (assuming the thermostat is operating normally)
What do you guys think?
I was thinking about how simple a temp sensor and a switchable outlet would be but other forums reminded me that the control point is then the Vera system so if something happens your whole control goes down … this method works independent of Vera and stays functioning as a closed loop - but has benefits of remotely changing the set point.
Feedback welcome - I’m still flushing out this idea and trying to find a good thermostat to try it with which is what the original intent of my post was - finding a thermostat that had a low enough set point capability.
If inclined I also attached a circuit diagram idea of the controller …
I think you will find it a problem to find a standard thermostat that works near the freezing level …
The reason … it’s not technical … they do not want liability if the thermostat is in auto mode and you have freezing damage!
Very good idea @RichardTSchaefer - that Qubino product almost does what I need - amazing how many google searches and I’ve not seen that brand even come up … maybe not popular in USA …
The problem with the heat product is the logic is fixed for heat, thus the hysteresis between actual and set point is inverted. I don’t think that simply switching a COOL load for a HEAT load works correctly.
This would allow proper logic in cool mode. It says 240VAC operation, but the manual show inputs from 110V upwards so it should work on US line voltage. The output is on 4A @ 240V or approx 1000W , which may be usable for some loads directly - if higher load is required it is still feasible to use an external relay.
I’ll keep digging as this might be the thermostat portion I was looking for if it’s Vera compatible and 120VAC compatible…