That’s what I wanted to know. In fact I never finished my thought from before where I was going to ask if there was a way to keep stage 2 running until the set point was reached.
So
would be incorrect. If you wanted the house at 74, you would set it at 74.
Oh of the two models that Grainger sells, one is only one stage, the other has 2 stage cool and three stage heat. Would that be to set up three furnaces?? Could I do the same with the heat as I am with the AC by using a jumper from the stage 1 cool (the fan) to the stage one heat? I’d be worried about sending electricity back into the tstat if there arn’t diodes to protect it.
A typical 3 stage application would be a single stage heat pump with 2 additional stages of electric heat. (called auxiliary, back up, oe emergency heat) Or, some furnaces have 2 stage gas valves. You could even have a set up that has a heat pump as primary heat with a 2 stage gas gurnace as backup heat. There are even 2 speed, 2 stage heat pumps. In that arrangement you could even have 4 stages (and sometimes 5) of heat; a 2 stage heat pump as primary and a 2 stage electric furnace as backup.
You cannot “do the same with the heat as I am with the AC by using a jumper from the stage 1 cool (the fan) to the stage one heat?”, and there is a variety of reasons why you can’t. What you describe would have both heat and cool running at the same time. Also, the fan is controlled in a different way in heating ,and runs at a different speed.
In heating, however, I doubt you need any of this. Heat rises. The “Circ” may be all you need.
I would agree and this time make a minor correction to Rhurbarb. If you set it at 74° it will maintain 74° at the stat location. However, in your scheme, the stat will respond quickly—within one degree— for stage 1. The problem is that your stage 1 will be a fan only. It will be another degree or so before stage 2 comes on.
So your arrangement will maintain at 74°, but the control won’t be as tight. In other words, before your stat responded quickly to maintain tight control. Now, it won’t be as tight. It will still get down to 74°, but it may get up to 76° before it gets to work.
The problem won’t be on the “back end”—getting back down to 74°. The problem will be on the “front end”, meaing there will be a delay of a couple degrees before is starts it’s work.
A good stat will provide very tight control. If you set it at 74°, it will stay very close to 74°.
Your proposed arrangement will result in 2-3° of “slop”, or “looser” control, however.
As Rhurbarb said, if you set the stat at 71°, the house won’t get any hotter than 74°—which is the logic of setting it at 71°. With this arrangement, however, the house will actually get to 71° at the stat location. So…your 3° of slop is at the low end of the setting.
The alternative, is to leave it at 74°. In this arrangement, the house won’t get any colder than 74°. With this arrangement, however, the house will actually get to 77° at the stat location. So…your 3° of slop is at the high end of the setting.
Did that make any sense?
ETA: 3° is nothing really. Most human will remain comfortable within 6-10° range.
sigh…I’m still trying to decide. I may just cough up the extra few dollars and get the two stage and then I can decide later if I want to wire it for 2 stage. I really like the circ idea though. Like I’ve said before, our house is really uneven and that maybe enough to keep us quite a bit more comfortable.
Okay, so I picked up the VisionPro 8000 (multi stage). For the moment, I’m going to set it up like a single stage tstat. On my ‘old’ tstat I have G W Y R[sub]h[/sub] R[sub]c[/sub] with Rh and Rc jumped. The new one has C G Y R and RC with R and RC jumped. Now, from what I can tell the wire going to Rh will go to R on the new tstat, but my old tstat doesn’t have a C wire. Is that going to be an issue? Is that wire optional if I’m using batteries?
I’ve read through the technical part of the manual, it seems that since I’m setting it, for the moment, as single stage and since I have a gas furnace, everything can be left as defualt. One thing though, the extended fan is set to off as a defualt. Am I safe to assume that that when the compressor or furnace is running, IT takes control of the fan? Normally, when the call for cool or heat ends, the fan does continue to run for a moment. I assume module down in the furnace takes care of that and that this setting is designed for systems where that doesn’t happen automatically (electric heat?).
Now, if I would ever decide to set this up as a multi stage, I beleive what I would need to do is move Y to Y[sub]2[/sub] and jump G and Y. Then I would change the setting to 2 Cool/1 Heat correct? Odd, there is a setting for that, but not a wiring diagram, but anyways. The only other thing I wouldn’t be sure about is a setting for compressor cycle rate. It’s default is “3” and I assume that’s where I leave it if it is controlling an AC compressor, but what if it’s controlling a fan?
If you weren’t using a C wire before, you don’t need one now. Some digital stats require the C terminal. (it is the “common” side of the 24V) The Vision Pro does not require it.
But…one of the menu items on the technical menu allows for the backlight to stay on all the time. (It’s very subtle and dim) IIRC, if you choose the option for the backlight to be on all the time, you must use the C terminal.
ETA: Yes it is optional, as long as you don’t select the “backlight on all the time” feature, in which case the C terminal will be required.
Given you have straight AC with standard gas heat, the factory defaults might be OK. (I don’t remember all the defaults) (I assume you have a single stage furnace and single stage AC)
Still, there may be a few items you may want to change. I usually bump the compressor cycle rate a bit, sometimes 4 or 5. Given that you’re going to be a little looser, I would bump it to 4 or 5. It won’t hurt anything to do that.
Your wiring assumptions are correct, but you’ll need to go back in the menu and tell the stat that it is now a 2 stage AC. (In fact it is NOT a 2 stage AC, you’re just wiring it that way)