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Thread: 25HNA648A300

  1. #1
    Join Date
    Feb 2009
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    Dubuque,Iowa
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    25HNA648A300

    In regards To Carrier model 25HNA648A300 used with Carrier FV4BNF005 fan coil. Some things to keep in mind; Carrier seems very reluctent to supply their distribuitor & sales network with the correct technical info. wiring diagrams, and operating specs. so a functional operating system is in place on any given customers location. MINE INCLUDED! The technical programing and wiring configuration requires a high degree of expertise. It may well tax the average HVAC installer's abilities. Plus the abilities of the area's distribuitor to supply the correct parts to put together a funcitional operating system. One big problem seems as in my case no one wants to admit the system requires knowledge which is above their ability. I have been trying for two years with only moderate success. And have reached the stage where it may become necessary to hire a lawyer to get things moving my way. $x is a lot of money for a system that only performs up to 3/5 of what it should. Would any of us accept a car under the same conditions? Can anybody supply me with the correct wiring configuration so I can check out my system properly? 25HNA648A300 2 stage HP. FV4BNF005 Fan coil with 20kw resistance aux heat, 2 piece Bryant thermostat with external control box.
    So far AC works perfect in the summer. But only 3 stages of heat will work in the winter. The 3rd stage adds 5kw of redistance when the temp gets down to 5deg F. Defrost works fine runs 15kw of res. heat. But Below zero down to -30deg F the Compressor never shuts down, and I never get any more than 5kw of additional res heat, Emergency heat will only run 5kw of res heat no HP compressor. Over all I believe there should be a total of 5 stages and 20kw of emergency available. Thanks for bending your ear. email direct please Richard
    Last edited by jrbenny; 02-05-2009 at 04:07 PM. Reason: remove price

  2. #2
    Join Date
    Jun 2001
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    Louisville, KY
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    What's your question, or do you just feel like griping?
    Perhaps you should have read the instructions before calling.

  3. #3
    Join Date
    Jan 2004
    Location
    Lancaster PA
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    66,774
    Wow.

    A whole county that no one knows how to wire, and check the system.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  4. #4
    Join Date
    Apr 2004
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    Midwest
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    5 stages of heat? Your using a thermostat that can only give you up to three stages of heat. I can guarantee there is no wiring diagram to give you 5 stages of heat.

    But it is not rocket science to figure out how to do it, I am just not sure it is worth the effort...probably why nobody is willing to put in the time to figure it out for you.
    Live each day like it is your last, for one day you will be right!

  5. #5
    Join Date
    Apr 2005
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    Tampa, Florida
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    Quote Originally Posted by hvac r us 2 View Post
    5 stages of heat? Your using a thermostat that can only give you up to three stages of heat. I can guarantee there is no wiring diagram to give you 5 stages of heat.
    Incorrect. The Infinity system w/appropriate Carrier heat strips & 2-stage HP outside will give you 5 stages of heat. 2 HP + 3 stages of electric.

    Regarding Infinity wiring, it's piss simple. 4 wires for everything. A goes to A, B goes to B, C goes to C, D goes to D. This needs to happen at the thermostat, fan-coil/furnace and heat pump/condensing unit. It's actually simpler wiring than a typical heat pump or multistage furnace. It pretty much works or it doesn't work. For the curious, A & B are Data +/-, C & D are 24vAC. If the wiring was incorrect you'd either have a blank screen or a screen saying communication failure.

    The devil's in configuring it, which isn't all that difficult if you truly understand HVAC. The installer menus are simple, but there are many options so you need to know your HVAC to set them properly. There's nothing wrong with the compressor running below 0F. Even Carrier's charts show performance data down to -3F or so. It's still putting out usable heat at that point, even if it's not able to carry the whole house on its own. At -3F it's still 1.5x more efficient than the heat strips.

    Another issue that comes up is when salesholes/techs/installers fail to understand that this is a communicating system. It works great as long as all of the parts in the system are communicating as well. This will mean real Carrier heat strips, not 3rd party. Additionally, all parts need to be communicating so that the controls are capable of controlling them discretely. Carrier's made provisions so that the system will work with 3rd party and misconfigured devices, but it won't work as well.

    Without seeing the original poster's system first-hand, I can't say for sure what's wrong. I'd suggest looking at the possibility of the configuration not being correct, the heat strips aren't the correct ones for the system, or both.

    At the same time it sounds like it is indeed acting properly when in emergency heat mode. It's not going to use all of the heat strips immediately. It will start off with the 1st stage and wait at least 10 minutes before it brings on the next stage. Thus, if you have 3 stages it could well take 20+ minutes for all 3 stages to fire up, and the system's only going to use more than one stage if it's not making progress. Note, making progress=temperature rising, *NOT* reaching the setpoint within that time period.

    I'm also curious as to where this system was installed. -30F?!? With a heat pump and electric strips? 20k worth of strips doesn't sound like a whole heck of a lot once you reach -30F. I would have expected some sort of fossil fuel system in there at that point.

    Ultimately, is the system capable of maintaining the design temperature 98% of the time? If so it's doing what it was supposed to. Usually more heat strips are installed than necessary, particularly with staged heat strips. Most contractors never want to get a call that the system's not able to keep up.

  6. #6
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    Might want to look at the OP's fan coil model number... FV4BNF005

    Perhaps you should have read the instructions before calling.

  7. #7
    Join Date
    Jul 2007
    Location
    Jacksonville, Fl
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    I sent the guy an email.
    Felt sorry for him after I found the closest Bryant Factory Authorized Dealer was 90 miles away, no Factory Carrier Dealers to be found. Only 2 Carrier Dealers with in 20 miles.

    Why on earth he got an Infinity Condenser and put a FV Air handler with it is beyond my recommendation since It would have been simple to go with the FE and Infinity Controller.

    To answer the question, The system only has 3 Stages of heat but a stage is a lower air flow differential.
    First there is something screwy if he is only getting 5kw of Aux Heat and 15Kw of EM heat when he has 20Kw of heating coils.

    First thing is to make sure the added Out door Temp Sensor is hooked up to the T6 Thermidistat ( I am hoping he has the T6) You do have a T6 Thermostat Richard? (As I cringe)

    The Infinity Condenser has a out door temp sensor built in but this one can only be used with the 4 wire communicating hookup so the extra sensor that comes with the thermostat needs to be attached to the outside condenser I normally hook up with 2 extra Tstat wires that are ran to the outside unit. They did install this sensor I hope?

    Next I would try:
    Inside Unit, Control board J2 jumper needs to be removed for heat staging.

    IF T6 Thermostat(Thermidistat)
    Stage 1 Heating wire hookup
    T6 Tstat W1 to A/H Control board W1

    Stage 2 Heat wire
    Tstat O/B/W2 to A/H Control Board W2
    T
    hen go to program options in the Thermidistat
    and choose option 44 Superheat comfort.

    Try that

  8. #8
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    Quote Originally Posted by jrbenny View Post
    Might want to look at the OP's fan coil model number... FV4BNF005

    A little hard to do Infinity with an FV fan coil eh JR? Where does the ABCD hook to? You know...I think I have taken that call! LOL
    Live each day like it is your last, for one day you will be right!

  9. #9
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    Apr 2004
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    Quote Originally Posted by ClassicDave View Post
    I sent the guy an email.
    Felt sorry for him after I found the closest Bryant Factory Authorized Dealer was 90 miles away, no Factory Carrier Dealers to be found. Only 2 Carrier Dealers with in 20 miles.

    Why on earth he got an Infinity Condenser and put a FV Air handler with it is beyond my recommendation since It would have been simple to go with the FE and Infinity Controller.

    To answer the question, The system only has 3 Stages of heat but a stage is a lower air flow differential.
    First there is something screwy if he is only getting 5kw of Aux Heat and 15Kw of EM heat when he has 20Kw of heating coils.

    First thing is to make sure the added Out door Temp Sensor is hooked up to the T6 Thermidistat ( I am hoping he has the T6) You do have a T6 Thermostat Richard? (As I cringe)

    The Infinity Condenser has a out door temp sensor built in but this one can only be used with the 4 wire communicating hookup so the extra sensor that comes with the thermostat needs to be attached to the outside condenser I normally hook up with 2 extra Tstat wires that are ran to the outside unit. They did install this sensor I hope?

    Next I would try:
    Inside Unit, Control board J2 jumper needs to be removed for heat staging.

    IF T6 Thermostat(Thermidistat)
    Stage 1 Heating wire hookup
    T6 Tstat W1 to A/H Control board W1

    Stage 2 Heat wire
    Tstat O/B/W2 to A/H Control Board W2
    T
    hen go to program options in the Thermidistat
    and choose option 44 Superheat comfort.

    Try that
    Keeping in mind, only the T6-RH thermostats have 3 stage heating ability. The T6-HP thermostats are only two stage heat.
    Live each day like it is your last, for one day you will be right!

  10. #10
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    Apr 2005
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    Tampa, Florida
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    Quote Originally Posted by jrbenny View Post
    Might want to look at the OP's fan coil model number... FV4BNF005

    DOH! That's what I get for posting when I should be heading off to bed. That ain't gonna work as it should. What a shame. Could otherwise be a good system with the FE AH.

  11. #11
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    Louisville, KY
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    It will work just fine with a contractor that can follow a wiring diagram and think for himself.
    Perhaps you should have read the instructions before calling.

  12. #12
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    Quote Originally Posted by tpa-fl View Post
    DOH! That's what I get for posting when I should be heading off to bed. That ain't gonna work as it should. What a shame. Could otherwise be a good system with the FE AH.

    LOL Could be like me and have a few beers and get up the next morning and go "what the heck did I post!".
    Live each day like it is your last, for one day you will be right!

  13. #13
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    Louisville, KY
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    Or what the heck did my wife post?





    Perhaps you should have read the instructions before calling.

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