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  1. #1
    Join Date
    Mar 2013
    Posts
    6

    Help with Aux heat options.

    Hello all I have been reading on here for months trying to decide what to do with our heating situation.

    We live in far eastern TN near Bristol, our heat pump seems efficient in the summer and until temps drop under 30-35 for long periods of time. We usually keep it about 68 to 70 in summer and for economy have been at 66 this winter. Our power bill jumps from average of $110-$150 from April til September then November to March it averages $320-&500 depending on temps. Our electric rate is .09/kW and have propane for fireplace, stove, and grill and supplier is about $2/gal when I checked two weeks ago. We are not going to be in this house long term but I am willing to make some investment to be comfortable in the winter months for the next few years. It seems if can utilize some existing equipment it could be a rather quick return on investment.

    Our house is not huge about 2000 square feet but it has a large living room with 20ft ceilings(recently doubled insulation in attic to R40 celloulose). Only rooms that are ever really comfortable are Master bedroom (shorter vaulted ceilings that are pretty well insulated) and upstais bedroom/bath which are open to livng room, but they are hardly ever used and are warm because of heat loss from living room. To further complicate things I am in the process of finishing the basement and will add approximately 1300 square feet with only back wall and half of sides underground. Also recently discovered that the inept builder did not use house wrap and lacked any real care with sealing in general so I imagine the heat loss will be very high. I am continuing to improve insulation/sealing issues as I have time.

    Current system is a 7 year old Rheem HP RPNE-048JAZ (R22)and RHLA-HM4821JA with electic Aux strips not sure which ones with 2 zones with Digitract 4 2 to 4 zone controller model DTHP4A. I noticed system also has a bypass damper installed from supply back to return. Also DMW is supplied by two 50 gal electric in series and the energy guide sticker on side says cost of over $500 per year for each.


    I would like to implement a propane aux whether it be by using a gas water heater(can be tankless or traditional) with hydronic coil in place of heat strips or going with a gas furnace with coil and utilize existing Rhemm outdoor unit either way. If go hydronic probably size to could add radiant in under about 900-1000 sq ft but from my estimations probably a answer for next house not a retrofit?

    Any input would be greatly appreciated, I am tired of blankets in the living room or turning on fireplace to look at while it just heats the upstairs for one of the cats.

    Thanks

    Eric

  2. #2
    Join Date
    Nov 2009
    Location
    Central Virginia
    Posts
    146
    Before you go too crazy with all of that, has anyone inspected your heat pump and duct work? Had any maintenance done? Such as cleaning the coils and blower wheel? If not I would recommend that. Stay away from the cheap coupons for tune ups in the newspapers and things like that. Look for a good company that has good references and has been around for a while. Keep us posted. Good luck.

    Sent from my SPH-D710 using Tapatalk 2
    ____________________________________________
    If you don't know what you are doing.... ASK!! There is no such thing as a "Stupid" question.... Maybe.

  3. #3
    Join Date
    Mar 2013
    Posts
    6
    thanks for reply

    Yes had unit serviced in November because of outside unit not coming on and was running on full strip heat. He said coils were clean and went over unit and filled with few pounds ofR-22 found leak at schrader valve. It has not malfunctioned since to my knowledge.

    System has always been this way I do not think it is a performance issue as much as wrong system for large cubic volume open to everywhere but master bedroom. Forced air is not best solution but it is what I have in place and seems can make it much more comfortable and efficient with out changing everything?

  4. #4
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,902
    To put a million BTUs in the house, the heat pump alone at 32 out will cost $8.11

    To put the same heat in the house with LP and a 95% furnace will cost $23.37

    To compare, your electric backup would cost $26.37

    So going to LP without a heat pump would be VERY COSTLY. Going dual fuel but shutting off the heat pump at 32 or so which most do with dual fuel, will be expensive. Be lots cheaper to leave the heat pump on with electric strips helping out occasionally. Hard to say whether there will be any comfort advantages. Most people even up here where we are lots colder are happy with their heat pump/electric system so your discomfort may not be the equipment but house construction or ductwork.

    If you go a traditional tank type LP water heater, there will no savings using LP, it will cost more. Figure the tank heater about 65% efficient. If you go with a 95% tankless, you will have a little savings but the annual maintenance on the tankless will more than eat that up. And they have a healthy up front cost $$. And one repair out of warranty and you're behind many hundreds.

  5. #5
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,242
    Quote Originally Posted by E_in_TN View Post
    Hello all I have been reading on here for months trying to decide what to do with our heating situation.

    We live in far eastern TN near Bristol, our heat pump seems efficient in the summer and until temps drop under 30-35 for long periods of time. We usually keep it about 68 to 70 in summer and for economy have been at 66 this winter. Our power bill jumps from average of $110-$150 from April til September then November to March it averages $320-&500 depending on temps. Our electric rate is .09/kW and have propane for fireplace, stove, and grill and supplier is about $2/gal when I checked two weeks ago. We are not going to be in this house long term but I am willing to make some investment to be comfortable in the winter months for the next few years. It seems if can utilize some existing equipment it could be a rather quick return on investment.

    Our house is not huge about 2000 square feet but it has a large living room with 20ft ceilings(recently doubled insulation in attic to R40 celloulose). Only rooms that are ever really comfortable are Master bedroom (shorter vaulted ceilings that are pretty well insulated) and upstais bedroom/bath which are open to livng room, but they are hardly ever used and are warm because of heat loss from living room. To further complicate things I am in the process of finishing the basement and will add approximately 1300 square feet with only back wall and half of sides underground. Also recently discovered that the inept builder did not use house wrap and lacked any real care with sealing in general so I imagine the heat loss will be very high. I am continuing to improve insulation/sealing issues as I have time.

    Current system is a 7 year old Rheem HP RPNE-048JAZ (R22)and RHLA-HM4821JA with electic Aux strips not sure which ones with 2 zones with Digitract 4 2 to 4 zone controller model DTHP4A. I noticed system also has a bypass damper installed from supply back to return. Also DMW is supplied by two 50 gal electric in series and the energy guide sticker on side says cost of over $500 per year for each.


    I would like to implement a propane aux whether it be by using a gas water heater(can be tankless or traditional) with hydronic coil in place of heat strips or going with a gas furnace with coil and utilize existing Rhemm outdoor unit either way. If go hydronic probably size to could add radiant in under about 900-1000 sq ft but from my estimations probably a answer for next house not a retrofit?

    Any input would be greatly appreciated, I am tired of blankets in the living room or turning on fireplace to look at while it just heats the upstairs for one of the cats.

    Thanks

    Eric
    $400 for 40,000 Btu/Hr [ approx. for 2,000 Sq Feet ] for 1,000 Heat Degree Days in ONE month
    ___ at $0.09 /kW IS Characteristic on 100% use of heat strips.

    http://www.climate-zone.com/climate/...-johnson-city/

    You need to start from FIRST Step and take it through an organized thought process to
    determine WHAT you Really Need.

    FIRST Step - Blower Door test and evaluation of heat loss.

    SECOND Step - Heat Pump Cycling and Performance need to be determined.

    More thought & DATA on Actual energy use per month is needed.

    Without a structured Heat Loss evaluation process, ADD 1,300 Sq Feet so the issue is 3 X more difficult.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  6. #6
    Join Date
    Mar 2013
    Posts
    6
    So I need to test heat loss, makes sense. Thanks for the advice on a actual process. I need to find a trustworthy energy consultant or HVAC contractor, then exactly what test do I ask for? I read something about Manual J?

    I know what the cost of 100% strip heat is as it happened December of 2010 and bill was $984, relay went out and I didn't notice outside unit not running.

    I can look up actual kW usage on my providers website. Will is help to know last few years energy use for winter months?
    Last edited by E_in_TN; 03-11-2013 at 10:17 PM. Reason: wrong date

  7. #7
    Join Date
    Mar 2013
    Posts
    6
    BaldLoonie I was proposing a dual fuel approach. I even considered a supplemental radiant for living room area that is hardest to heat using pex under floor and floor thermostat? but I dont know what impact would be on forced air system for rest of house?

    Sorry to be all over the place just trying to get ideas on what to do before next season.

  8. #8
    Join Date
    Mar 2013
    Posts
    6
    I did a little research on utility site, below is all the kW usage info I could get with out requesting further back. A note about this past summer, in June and July we had record heat something like 30 days of temps of 95+ Also there was a rate reduction to the current $.09 somewhere in there dont remember the date but was from $.12 i think in 2011

    I also found that Utility company will setup a TVA energy audit for $150 with a reimbursement/rebate if you do suggested improvements. Not sure if includes door test or not going to call as soon as I can.

    Should usage almost double for winter months?

    Month kW
    03/04/13 3380
    02/01/13 3400
    01/03/13 4090
    12/03/12 3740
    11/01/12 1900
    10/03/12 1320
    08/31/12 1600
    08/02/12 2000
    07/02/12 1880
    06/01/12 1340
    05/02/12 1410
    04/02/12 2040
    03/02/12 3900
    02/02/12 3110
    01/04/12 3780
    12/02/11 2410
    11/02/11 1600
    10/04/11 1510
    09/01/11 2270
    08/02/11 3040
    07/01/11 1650
    06/02/11 1510
    05/03/11 1360
    04/01/11 1770

  9. #9
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,242

    What portion of electric bill is related to Heating?

    Quote Originally Posted by E_in_TN View Post
    I did a little research on utility site, below is all the kW usage info I could get with out requesting further back. A note about this past summer, in June and July we had record heat something like 30 days of temps of 95+ Also there was a rate reduction to the current $.09 somewhere in there dont remember the date but was from $.12 i think in 2011

    I also found that Utility company will setup a TVA energy audit for $150 with a reimbursement/rebate if you do suggested improvements. Not sure if includes door test or not going to call as soon as I can.

    Should usage almost double for winter months?

    Month kW
    03/04/13 3380
    02/01/13 3400
    01/03/13 4090
    12/03/12 3740
    11/01/12 1900
    10/03/12 1320
    08/31/12 1600
    08/02/12 2000
    07/02/12 1880
    06/01/12 1340
    05/02/12 1410
    04/02/12 2040
    03/02/12 3900
    02/02/12 3110
    01/04/12 3780
    12/02/11 2410
    11/02/11 1600
    10/04/11 1510
    09/01/11 2270
    08/02/11 3040
    07/01/11 1650
    06/02/11 1510
    05/03/11 1360
    04/01/11 1770
    After review of this electric bill history and correlation to Heating Degree Days (HDD) and Cooling Degree Days (CDD),
    I see that there is a "baseline" use of about 1,400 kW/ month that is NOT related to either Heating or Cooling.

    See Attachment for graphical correlation of electric data and CDD/ HDD data from Wunderground.

    Next step is to perform a simplified heat loss calculation.
    __Factors needed
    Ceiling R_ _____ ? R-40 mentioned above
    Walls R- ______ ?
    Windows U- ___ ? Window (glass) Area ____ square feet ... 220 or so?
    Infiltration ____ ? seems like 1.0 A.C.H. or more - Air Change per Hour
    Attached Images Attached Images
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  10. #10
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,242

    DETERMINING HEAT LOSS AND MAXIMUM ELECTRIC USAGE

    Maximum heating ELECTRIC usage should be < 3,080 KW [ ~ $277 one month a year] with 1/3 for electric strip.
    Heating Degree Days ( HDD) of 1080 was used for December 2010 to determine heat loss of 46,000 BTU/Hr at 11'F design temperature.

    ATTACHMENT


    Comparison of attachments ( upper right section) indicate going from Air Change per Hour infiltration (ACH) 0.94 to 0.30 would save 25% of overall heat loss.
    .:. Blower door test is needed to determine current actual leakage in a realistic manner and associated benefit.
    Last edited by dan sw fl; 03-15-2013 at 12:34 PM.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  11. #11
    Join Date
    Mar 2013
    Posts
    6
    Dan thanks so much for all the info, trying to absorb all I can. I am out of town until Sunday, I will start gathering the info to help determine heat loss as well as contact someone to do a door test. Is a door test typically included in a engey audit from a utility or gov agency like TVA?

  12. #12
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,242
    I believe blower door test is Becoming QUITE COMMON, but electric utilities in various regions are not all that similar in their Load Management Objectives/efforts.
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  13. #13
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by BaldLoonie View Post
    To put a million BTUs in the house, the heat pump alone at 32 out will cost $8.11

    To put the same heat in the house with LP and a 95% furnace will cost $23.37

    To compare, your electric backup would cost $26.37

    So going to LP without a heat pump would be VERY COSTLY. Going dual fuel but shutting off the heat pump at 32 or so which most do with dual fuel, will be expensive. Be lots cheaper to leave the heat pump on with electric strips helping out occasionally. Hard to say whether there will be any comfort advantages. Most people even up here where we are lots colder are happy with their heat pump/electric system so your discomfort may not be the equipment but house construction or ductwork.

    If you go a traditional tank type LP water heater, there will no savings using LP, it will cost more. Figure the tank heater about 65% efficient. If you go with a 95% tankless, you will have a little savings but the annual maintenance on the tankless will more than eat that up. And they have a healthy up front cost $$. And one repair out of warranty and you're behind many hundreds.

    In those rates, I don't know if you factored in that with electric resistance or hydronic bakc-up the HP keep running and generates heat, so the ocmposite COP is >1, WIth a dual fuel, it's either/or, so you don't get to run the heat pump while the furnace is running.


    For example, with a Carrier Greenspeed heat pump, it's optimized for capaicity and according to data sheets actually has a lower COP <40F than a Infinity 16 or 19 heat pump. However, it produces a lot of capacity, so it won't need the heat strips nearly as much, so the overall effciency is much much higher.

    Same with the series 7 inverter geothermal unit by Waterfurnace. The COP's are not much better than a Series 5, but it has a LOT more capacity in heating. Almost twice as much at lower water temps. That mean very littlte or no heat strips needed.


    That also means that despite it's advertising, Greenspeed is nice for propane dual fuel, but for natural gas the Infinity 19 for a lot less moeny is a better choice IMO, unless you want hte Greenspeed for other benefits sunc has it's turndown rate for zoning, or if you have a long cooling season and SEER is more improtant than low temp heating COP.

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