outdoor coil temp? why do I care?
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  1. #1
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    Dec 2011
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    outdoor coil temp? why do I care?

    Scrolling through the menus on my t-stat, I can see the outdoor coil temp. I can't find anything in the literature that tells me what to do with this information. Is there anything I can decipher from this, like something that could point to a developing problem that could alert me to call a tech before the problem gets huge? thanks, Mike

  2. #2
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    Apr 2004
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    NJ
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    Outdoor coil temperature is relevant because that is how the heat removed from the conditioned area is released to ambient air.

  3. #3
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    May 2000
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    Indianapolis, IN, USA
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    Not something a homeowner needs to know. Maybe they put that there to aid a tech in servicing.

  4. #4
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    Dec 2011
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    Hiram, Ohio
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    kinda figured, since it didn't get mentioned anywhere in the paperwork. I would assume that if it reached a certain threshold, (whether that be low or high) it would shut the system down? Thinking it through, for instance, if the outdoor fan quit the coil temp would get too hot in AC mode, and too cold in heat mode. My wife wishes I could just take things on faith that they just work correctly and not need to understand HOW things work all the time. As always, thanks for the time you spend answering my questions. Mike.

  5. #5
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    Jan 2009
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    Keokuk, IA
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    It might give you an indicator that there's it's needing to be cleaned. However the delta T can vary based on outdoor conditions in heating and in cooling. Direct sunlight hitting hte unit will also make the outdoor temperature read a little higher too. In heating mode, high relative humidity will cause hte coil to either creat condensate or frost, which will also reduce the temp difference.

    If your condenser fan shuts off, unless it's cool outside in cooling mode, the unit will shutdown on high pressure fairly quickly and throw a fault code.

    As mentioned above, not osmething hte homeowner sreally needs ot know about. More useful for troubleshooting.

    What brand system is this? Is this Carrier Infinity/Bryant Evolution? If so, you have to be in the service screens to see this. Be careful in there. You can change settings that can cause some issues in some cases.

  6. #6
    Join Date
    Jun 2005
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    SW Wisconsin
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    Quote Originally Posted by troyport View Post
    Scrolling through the menus on my t-stat, I can see the outdoor coil temp. I can't find anything in the literature that tells me what to do with this information. Is there anything I can decipher from this, like something that could point to a developing problem that could alert me to call a tech before the problem gets huge? thanks, Mike
    Exactly what is it telling you concerning the condensing temperature?

    Does it read the operating condensing temperature?
    Is it telling you what the condenser temperature should be at those conditions?

    I have not seen any information on that thermostat...
    Read & type the TH instructions to us...

    I use published performance data showing the high pressure then I convert it to temperature using an R-22 or R-410A pressure/temperature chart.
    That tells you what the condensing temp should be; if it's a lot higher than the indoor humidity indicates it should be; the return air could be pulling hot humid air from he attic.

    If the temperature according to the SEER is considerably below where it should be, under those input numbers; a whole list of possible causes immediately flash into the mind of a proficient TECH.

    The condenser temp as related to the indoor temp-drop & humidity level indicates many possible scenarios, that further testing can help pinpoint.

    Depending on knowing what the thermostat is telling you about the condenser temp; that could be very helpful to me...

  7. #7
    Join Date
    Dec 2011
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    Hiram, Ohio
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    214
    The system is a goodman comfortnet. This outdoor coil temp can be seen in the set up screen. I didn't see anything that would be drastic if I changed it, plus all of it is quite intuitive, would have to be pretty dumb to mess it up, about the only thing is fan speeds, but can only go +/- 10% off what the system self-decides it should be. This is a 3-ton system, so it chose 1199 cfm. Thought that was strange, why not choose 1200? But anyway...

  8. #8
    Join Date
    Feb 2009
    Location
    Tallahassee, FL
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    If you are going into installer menu for outdoor unit to view coil sensor it is for defrosting troubleshooting purposes.

    There is also a outdoor temp (not necessarily coil temp) that is viewed either on home screen or in normal menu.

  9. #9
    Join Date
    Dec 2011
    Location
    Hiram, Ohio
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    214
    thanks for that answer, SBKold... And yes, I love my outdoor ambient sensor! It added another cool icon to my t-stat! I'm such a nerd.

  10. #10
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    Jan 2009
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    Keokuk, IA
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    It may choose 1199 based on your static pressure. I know Carrier Infinity corrects for static pressure and altitude to a certain extent. There's are also minimum and maximum blower motor RPM's. Its calculaitons may simply have not rounded it down to 1199.

    If it's like Infinity, (I think its close, but probably has a little bit simliar logic) it will change CFM based on indoor temp and humidity and outdoor temperature. its' not a fixed CFM. I think Goodman likes ot use a fixed temp rise on hte furnace if you have a modulating furnace. Carrier allows a high temp rise in intermediate than in low fire or high fire.

    Comfortnet looks like a nice controller overall. The big advantage being that it's a controller, not a thermostat, so it measure actual temperature and reponds accordingly and stages equipment based on rate of change more precisely and can adjust CFM as needed based on conditions.

    I think in 5-10 years we'll see equipment that is even more reponsive to varying loads, conditions and hopefully even integrates with smart power meters and cna manage fuel soruce on dual fuel even more accurately based on electric rates and outdoor conditions. They are so, so close.

  11. #11
    Join Date
    Dec 2011
    Location
    Hiram, Ohio
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    I've had the propane furnace for a year, and the temp rise was always within a few degrees, regardless of stage. Yes, I have thermometers permantly installed. The only thing I didn't think it did well was choosing which stage to use, but I feel that will improve with the outdoor ambiant temp sensor I now have. Regardless of outside temps (which certainly affects how quick the indoor temp will respond) the staging was the same when coming out of setbacks, and would sometimes overshoot one degree if it was suddenly warmer out. I would really love to know how this new system will react to indoor humidity and indoor and outdoor temps, as you stated above, with regulating blower speeds. Is there any way I could get my hands on this kind of information? All I have been able to find is the generic glossy brochures that tell me how awesome it is. BTW, when the furnace was installed, on high heat and therefore high blower, tweaked to be in the middle of the acceptable range of temp rise, the total static was .48 with clean filters.

  12. #12
    Join Date
    Jan 2009
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    Keokuk, IA
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    If Comfortnet responds to vary conditions... the logic probably isn't published.... or too complicated to put in a simply table or chart because there's more than 2 vairables.

    I know Carrier doesn't give much info on Infinity logic. I've learned from just observing my system's reponse to different conditions. I've seen 1st stage in cooling at 410CFM when dehumidifying in warmer outside conditions in humid indoor weather. I've also seen it a full 600CFM with low humidity indoors and cool outdoor conditions. In heating it's been from 398-600CFM depending on outdoor temps.

    You can get more info on Goodmans webpage for product data. Most furnaces with vairable speed blwoers will allow a 60F temp rise up to about 0.8-1" static. SOme modulating furnaces will allow as high as 80F temp rises at lower firing rates.

    I just depends on the mfg. You can lose just a little effciency with temp rises over 50F. But we're probably talking 1/2% or so and the electric savings will probably cover that loss.

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