How to Set to a specific temperature

[twohawks]

Hmmm, I searched some manuals, and here on the forum, but for the life of me I cannot find, or figure out, how to set the HAI tstat to a specific temp from the automations (fro a macro), just as the occupant may do physically by pressing buttons at the Tstat Console.

I got an Omni IIe upgraded from a 950 to an 1106W, using PC Access 3.x...
...and a simple HAI thermostat.

All I got in under the 'action type' "Temperature" are..
- Cool and Heat and De/Humidity setpoints
- Fan
- Hold
- Mode

And then if you select Hold you cannot tell it to "Hold AT XX degrees", you can only tell it to Hold On/Off.

Someone suggested they place the Heat and Cool Setpoints to the same number and then set Hold ON, however, this system will not allow Cool and Heat setpoints to be on the same number (as I expected having read the manual and observing the 4 degree margin). Trying variations of this is just like playing bop-amole.

So while I am trying other things... how in the heck do you simply tell the thermostat, from the HAI automation, to keep the place at XYZ-temperature for the day, and LMNOP-temperature for the night?

What am I missing?

Feels like a stupid question, especially since I don't see it having been asked before... must be something obvious.

??
Thanks for any insights.

 

[HAI_fjh]

OK let's see if I can explain a few things...

The HOLD mode disables the internal scheduling (if enabled) and remote commands. Typically this is used to prevent the automation from controlling the system.

You don't set a specific temperature, you set a temperature range and depending on the HVAC system there is usually a required 3 or 4 degree separation.

In a typical configuration you would disable the thermostat's internal schedule/programming and let the Omni handle it.

You would set the high and low set points for the "daytime" temperature at your normal wakeup time.

You would set the high and low set points to the "away" temperature when you arm the system "away" and go off to work.

You would restore the "daytime" set points when you return home and disarm the system.

You would set the "night time" high and low set points when you go to bed.

All of this can be accomplished using "Buttons" (a.k.a. macros) or by triggering off the arming mode of the system or a combination of both.

Remember that if HOLD is on then the thermostat will ignore all set point commands. If you don't want the user to be able to override the automation then just set HOLD OFF before issuing any set point commands.

 

[twohawks]

Thank you, HAI_fjh,

That's how I generally have understood it to work, and how I have done it (basically) till now.
Then my client asked me to have the system set a specific temp, and I couldn't figure that one.
Scratching my head I thought, well that's weird... anyone can set a hold temperature at the tsat con, surely you can do that in the automations, but I couldn't suss it.
Then I asked one of our integrators back east, and he advised setting cool/heat setpoints the same (method), but that method is a no go (with what I have deployed here anyway).


Thanks again for your clarifications. I will advise my client we cannot do what he asks, but only the setpoints.

Cheers,
Twohawks

 

[twohawks]

Can you clarify... is the following the correct understanding...

The manual mentions 4 degrees off the setpoint.... I understand that to mean that if the setpoint is reached, then the hvac (assuming its not on hold, obviously) will alter the temperature until it moves 4 degrees from the setpoint (in the intended direction) before switching off hvac.

So therefore, assuming 4 degrees is correct, I would presume that you need to keep the setpoints spread apart by a minimum of five degrees, and really, only set them that close if you can be assured there is no continuing drift in temperature once the shut off value is reached.

So for instance.... IF I want to target a mean-temp of 72 degrees, AND I have observed the temp in this locale doesn't drift beyond 4 degrees when it kicks off, THEN theoretically one can do the following....
70, 71, 72, 73, 74, 75 target= ~72, so coolsetpoint=75, and heat setpoint=70

Of course, I am not so confident setting it so close, so how I actually do it is...
69, 70, 71, 72, 73, 74, 75 target= ~72, so coolsetpoint=75, and heat setpoint=69

Seems acceptably practical to me for when the resident is here, however, I would be interested in your feedback.

Thanks again.
Twohawks

 

[tmbrown97]

I don't think you understand the setpoints correctly - or I'm not reading something correctly.

The point of the different setpoints is so that the heater and A/C don't battle each other - heating then cooling then heating again.

Most of the time, you're really only using the Heater or the A/C - at least in my neck of the woods... there's only 2 short periods each year where the system would use both the heat and the cool setpoints, and that's the couple weeks as we transition into summer and as we transition into winter - when the house gets just hot enough during the day to need the AC and just cold enough at night to need the Heater.

The system won't drift past the setpoints. For example, if you have the house set to Heat=68 and Cool=72, what'll happen is that as soon as the temperature reaches 73, the AC will kick on, and it'll stay on until 72 is reached, then it'll turn off - there's no drift there. Should this be the time of year where it gets cold enough at night, then the house might start getting colder inside over the course of the night. Should the inside temperature drop below 68 in this example, the heater will kick in (at 67 degrees) and will run until 68 degrees is reached, then it'll stop - again, there's really no drift - those are the high/low temperatures you'll have in the home.

If you do as in your example, where target is 72, and you set 69/75, the only time the temperature will be 72 is as the house is slowly cooling down at night - the rest of the day it'll be too warm/cold while under control of the HVAC.

When you say that the client can set a single temperature, what they're really doing is setting either the heat or the cooling setpoint - it just so happens if they're in Heat or Cool modes, only one end of the setpoint is needed and the other is generally hidden from the thermostat screen. In the background it's still behaving exactly the same as you see on the computer - if you set a cooling setpoint of 70 degrees, it's automatically setting the heat setpoint to 66. The only time the two setpoints come into play together is in Auto Mode where the system switches from Heat to A/C as required to maintain a temperature between the two setpoints.

I hope this makes sense - it's very different from where you thought was going on.

 

[HAI_fjh]

Good answer Work2Play...

 

[twohawks]

Thanks for the clarifications, Cocoonut.

Sooo, I'm not there yet ;^)

Couple things then...
1) In the mountain locale (for one of the deployments) you can never know when its going to be cool or hot thoughtout a day or nite... so cooling and heating gets used in, say, a non-conventional way (assuming we are referring to what you layed out as being "the more conventional" way.

2) I imagine that when I get an outdoor temp sensor deployed I will be able to use "more conventional" method by having the system look at that for determining which mode (cooling or heating) to be in (at those junctures where I am affecting a new setting [day/nite/etc], and perhaps sampling at strategic points inbetween). So if its warm that nite, we can take the approach of 'keeping it down', whereas if its chilling down out there, we want to be 'keeping it up', kind of thing.

3) So then the 3-4 degree separation for setpoints is just that, a margin of separation. Thanks for clarifying that (boy was I off on that one).
This can make things a bit easier, especially once I get an outdoor temp sensor deployed.

So, all said, in a non-predictable environment where the client wishes the hvac to work in auto mode (alternatively cooling and heating depending on the shifty environment) it seems I can safely go ahead affect an auto-state and set my best assumptions, kind of like...

Daytime target 72, try heat setpoint 70, cool setpoint 73
Nite target 68, try heat setpoint 67, cool setpoint 70

Thanks for the help, guys. Please feel free to rough me up some more on this if my thinking is still skewed ;^)

 

[twohawks]

Oops.. I meant "Thanks for the clarifications, Work2Play."

 

[tmbrown97]

No prob! You say Nevada - out of idle curiosity, are we talking about a Vegas desert-style climate, or a Tahoe/Reno type climate?

Another member here did a writeup a while back about using some logic to know which way to set the tstats based on if he's going for heating or cooling; I wish I could find it. Anyway - sounds like you got the idea now - good luck!

 

[twohawks]

Yeah,

This is in the Sierras (mountains) so its a crap shoot in the spring + summer.

Thanks Work2Play ...and HAI_fjh ;^)

 

[tmbrown97]

Cool! If you ever need an additional hand, I'm only about an hour away.