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  1. #1
    Join Date
    Apr 2012
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    Carrier Infinity and power outages: solutions?

    In May I upgraded my 18yr AC to an Infinity Carrier HPAC (25HNA9). This works with my aging (but still functional) natural gas boiler. An interface relay kit (KFAIF0101HWC) is installed so that the Infinity tstat (SYSTXCCUID01) can control the boiler.

    On the old setup, a basic programmable thermostat (with battery backup) was used. The boiler was connected to generator (via a transfer switch). Thus, during power outages the boiler would still work.

    Well, the recent outage here in Maryland revealed something obvious: the Infinity Tstat was completely dead. That means no AC, and No Heat. While No AC is not fun but tolerable, No Heat is not in the plan; a lot of the reason for investing in the genset-transfer-switch was to have winter heat!

    So how to solve this? No way I can power the HPAC system off my generator, but is there some way to just power the Infinity tstat (and possibly the interface relay kit)? If not, I wouldn't mind reinstalling the old tstat (or real simple analog tstat), perhaps with a manual switch to select whether the boiler is controlled by the Infinity tstat or the old tstat. Or, perhaps a simple timer near the boiler, that could be turned on when the Infinity tstat is out of commission (i.e.; it would override the Infinity tstat control).

    Any suggestions?

  2. #2
    Join Date
    Dec 2010
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    Palm Beach,Fl.
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    Why can't you hook up the system to the generator? If all you really need is heat you can still power the tstat and just turn off the breaker to the AC unit.
    Quote Originally Posted by k-fridge View Post
    The laws of physics know no brand names.

  3. #3
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    Apr 2012
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    Quote Originally Posted by SoFlaDave View Post
    Why can't you hook up the system to the generator? If all you really need is heat you can still power the tstat and just turn off the breaker to the AC unit.
    Which to hook up? Just the fan coil breakers (not the condenser breakers)? How to suppress the fan (no need to push air)? Also, the breakers would take up several spaces in the transfer switch sub panel (only one free now).

  4. #4
    Join Date
    Jul 2008
    Location
    Rochester NY
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    No hydronic coil in AHU? Boiler is pure backup to the heat pump?

    Put the tstat back on the boiler and set to 3 degrees lower than your lowest anticipated heating temperature. Ie, if you don't go below 68, set boiler tstat to 65. Communicating features don't matter to the boiler.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  5. #5
    Join Date
    Apr 2012
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    Quote Originally Posted by tedkidd View Post
    No hydronic coil in AHU? Boiler is pure backup to the heat pump?

    Put the tstat back on the boiler and set to 3 degrees lower than your lowest anticipated heating temperature. Ie, if you don't go below 68, set boiler tstat to 65. Communicating features don't matter to the boiler.
    Almost:, no hydronics in AHU; boiler is used below freezing (I have hp set to shut off at oat of 35 degree, at which point the boiler kicks in ).

    The problem with your idea is that 99% of the time (when grid electricity is available) I DO want the Infinity tstat to control the boiler. Is it possible to somehow have two tstats connected to the boiler (say, drop a pigtail from the two wires going to the tstat from the boiler).

  6. #6
    Join Date
    Jul 2008
    Location
    Rochester NY
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    You on natural gas? There a reason you want to run the boiler?

    My mother has hna6. It heats her home fine to 6f. The 9 will do it, cheaper. And it knows if defrost is needed, so no "every 45 minutes" energy wasting bs. And with perfect humidity control...

    Might want to reconsider your approach.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

  7. #7
    Join Date
    Jan 2004
    Location
    PA
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    Have your contractor add a "back up" thermostat that only connects to the boiler. Set it for a lower temp then the Infinity control. power goes out in winter, and the "back up" stat will bring the boiler on.
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  8. #8
    Join Date
    Apr 2012
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    Quote Originally Posted by tedkidd View Post
    You on natural gas? There a reason you want to run the boiler?

    My mother has hna6. It heats her home fine to 6f. The 9 will do it, cheaper. And it knows if defrost is needed, so no "every 45 minutes" energy wasting bs. And with perfect humidity control...

    Might want to reconsider your approach.
    Yep, the boiler runs on natural gas (been using it for heat since I bought the house in 1992).

    Truth be told, haven't actually used the HP in cold weather (just got it installed in June 2012). Perhaps the HP will work comfortably and cost effectively when the temp drops below freezing. But maybe not. Having the boiler take over at low temps is a nice alternative.

    AND-- during power outages, the boiler is a very convenient choice; no way the HP can run off my 6.5kw genset (I have never lost natural gas service, electricity I lose for a few days every few years).

    Otherwise, quite happy with the AC performance of the unit -- excellent humidity control, easy to use (and customize) tstat. Seems to be energy efficient, but will need a few more months of data.

  9. #9
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    Apr 2012
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    Quote Originally Posted by beenthere View Post
    Have your contractor add a "back up" thermostat that only connects to the boiler. Set it for a lower temp then the Infinity control. power goes out in winter, and the "back up" stat will bring the boiler on.
    That sounds like a good solution. I assume the existing two wires coming from the boiler would be used -- they would split (before getting to the Infinity tstat); with one pair going to the Infinity and a different pair going to the backup tstat.

    Hmm, actually, I am pretty sure the wires from the boiler bypass the Infinity tstat and go straight to the interface unit. Thus, I assume the goal is to have the backup tstat connected to the boiler in a manner that does not require passing through any of the Infinity components (tstat, interface unit, etc).


    But just so I get it clear:

    The Infinity will have a setpoint, say 68 degrees.
    The backup tstat will have a lower setpoint, say 63 degrees
    The Infinity will switch from HP to boiler at an hp lockout (say, 35 degrees)

    When utility power is available, the Infinity is controlling; using either the HP or the boiler (depending on oat). House temp is always high enough, so the backup tstat never does anything.

    When utility power is not available, the Infinity is off line. The temp drops to the backup tstat setpoint, at which point it turns on the boiler.

    This implies that having two thermostats "telling" the boiler different things is not an issue. Please correct me if I a wrong, but I presume that "telling the boiler to run" is an active event; a tstat has to send a signal of some kind. In contrast, "telling the boiler not to run" is an passive event -- a tstat is NOT sending any signal.

    So if either tstat is sending a signal, the boiler turns on. If neither, it doesn't turn on. And, if due to some fluke or missetting of setpoints, both tstats send signals to "turn on", then the boiler will turn on without a problem.

    That is: here is no problem of somehow bolloxing the boiler (or tstats) with multiple "turn on" signals from multiple tstats?

    BTW: my contractor did an acceptable job, but the combo of hpac and existing boiler was unusual for them ( it took them a few visits to get the proper interface kit installed). Reenabling "boiler heat during outages" is also unusual (I asked them about this a month ago and haven't heard back -- I figure they have more pressing business during this never ending heat wave). That's is why I am asking questions here, so I can speak to them with some credibility when cooler weather arrives and they get less busy.

  10. #10
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    Ya, it wouldn't hurt anything if both the Infinity and the back up stat both called for the boiler at the same time. The interface and back up stat are both just switches.
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  11. #11
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    Quote Originally Posted by beenthere View Post
    Ya, it wouldn't hurt anything if both the Infinity and the back up stat both called for the boiler at the same time. The interface and back up stat are both just switches.
    Thanks. When next I talk to the contractor I will ask for this.
    Or maybe I will be ambitious and try it myself :<>

  12. #12
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    You short something out, and there goes your warranty.
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    How many times must one fix something before it is fixed?

  13. #13
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    Quote Originally Posted by beenthere View Post
    You short something out, and there goes your warranty.
    Upon factoring in that feature ... my maybe just got a lot more "maybe not" !

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