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HVAC logic based on OUTDOOR temperature


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Hello all,

As an extension to a prior thread, how can I have the system change the HVAC settings based on outdoor temperature? For example, run the air exchange fan while the A/C is running but only when the outdoor temperature is less than 80 degrees?

TIA.

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Thanks, but I was hoping someone knew a way to do it using the "internet" temperature that's displayed on the navigators. The fact that the system knows the outside temperature leads me to believe that there is a variable for it somewhere, I just can't figure out where.

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Hello all,

As an extension to a prior thread, how can I have the system change the HVAC settings based on outdoor temperature? For example, run the air exchange fan while the A/C is running but only when the outdoor temperature is less than 80 degrees?

TIA.

Is your 'air exchange fan' an ERV unit? If so how are you using C4 to control it?

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No, I have a Venmar unit. I'm planning on using a standard 120v C4 plug switch to turn it off and on. I was hoping to do it using outdoor temperatures, but for now I guess I'll have to do it empirically using time of day.

@Matt: what is a CA device?

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@Matt: what is a CA device?

Card Access' date=' they make things such as contacts and relays that are zigbee and tie into the C4 ecosystem. They have options for external temp probes.[/quote']

All most of the units have internal temp sensors.

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Anyone willing to share their programming logic? I have been playing around this a bit and am struggling some. I also want to include an announcement that tells me when the outside temp is cooler so that the A/C can turn off and we can manually open windows.

Also, is anyone strugging with a CA temp probe not reading accurately? Ours does not appear to be linear across temperature ranges. For example, when the outside temp is 75F (using multiple online services), the CAdisplays 70F. At 85F outside temp, the CAreads the same. And when the outside temp is 95F, the CA reads 102-103F. We haven't tracked this during the winter months though. Ours is installed in a garage soffit overhang (so it never sees direct sunlight).

Your help is appreciated.

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Anyone willing to share their programming logic? I have been playing around this a bit and am struggling some. I also want to include an announcement that tells me when the outside temp is cooler so that the A/C can turn off and we can manually open windows.

Also, is anyone strugging with a CA temp probe not reading accurately? Ours does not appear to be linear across temperature ranges. For example, when the outside temp is 75F (using multiple online services), the CAdisplays 70F. At 85F outside temp, the CAreads the same. And when the outside temp is 95F, the CA reads 102-103F. We haven't tracked this during the winter months though. Ours is installed in a garage soffit overhang (so it never sees direct sunlight).

Your help is appreciated.

OK this is off the top of my head but I think it should work.

You can go into Programming and select the CA driver.

Select the option for Temperature - When temperature changes. Next go to programming and select the CA driver in Actions. Select Temperature and you can add an if xx temperature is yy

in your situation, you can then select the thermostat and add a nested if the temp on xx is or if the cool set point it.....

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  • 1 month later...

What about humidity? Is there a sensor that would add that as a element of the equation on when to run A/C, close windows/shades, run whole house fan, etc.?

I know the new WeatherHawk stuff is slick but I should be able to do 90% of what I want to do at a fraction of the cost.

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I will talk to my superiors about possibly getting a humidity control device created, there are already several that consist of a device that has variable resistance and I think a variation of our smart pressure sensor or external thermistor driver may just do the trick. One thing that would be good to know before they go forward with this would be how many people would actually be interested with a humidity sensor and would use one to base programming on?

Aaron @ Card Access

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Thanks for the responses. I can tell you is if energy management with stuff like Eragy takes off, this would be an essential part of a system that somehow integrates fresh air as part of that management (tired of my house being hotter than it is outside, therefore I currently have high CFM whole house fan integrated with C4, and have all the pieces to open up casement window automatically when that turns on, although that isn't quite setup or integrated yet.) A set humidity level trigger may prevent that from happening.

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I'm using a QuickCool model QC4500. It just sucks air into the attic. It has two fans and I have them on a C4 outlet switch so I can control them independently.

I'm using a motor designed by Wintrol, but sold through Truth to open the casement window. Wintrol's web site is great:

http://wintrol.com/motors.htm

I've got them wired but not hooked up yet. I just ordered 2 sets to start, I want to automate at least one more window.

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  • 1 month later...
  • 8 months later...
  • 2 weeks later...
  • 6 months later...

Wintrol links live on web.archive.org--lots of good PDFs here for using the hardware you can still buy through Truth, only one was missing that I tried to pull and archive...

For example, https://www.truth.com/main/pdfs/Sentry%20II%20brochure.pdf

http://web.archive.org/web/20120102123442/http://wintrol.com/index.htm

Here's the page with docs on Truth's website for completeness:

https://www.truth.com/main/homeowner/technicalsupport2.cfm

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Yeah, but "losing" that Wintrol stuff was really a crime as it was really good stuff, so I wanted to update the status.

By the way, if anybody bothers to try to automate windows and whole house fans like I did, you better make sure your family doesn't have allergy issues. I can't even run my stuff when it would make the most sense (hotter inside than outside during the summer), because it bothers my spouse so much.

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