Number crunching

Discussion in 'Fred's House of Pancakes' started by Leadfoot J. McCoalroller, Apr 22, 2022.

  1. Louis19

    Louis19 Junior Member

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    My pleasure, , I bought a low temperatue inverter driven heatpump after deciphering the datasheets of different machines, i finally understood the the ins and outs by this lecture explaining the mambo jambo of the terminology . If you can spends about 30 minutes this is a mustcold climate heatpump seminar - Bing video
     
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  2. Salamander_King

    Salamander_King Senior Member

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    Thanks, both for the information. I have not checked the Fujitsu docs @fuzzy1 linked, but using the site @Louis19 mentioned, I came up with the following table. The database query is a bit archaic and the advanced search was not working for me. After several "free" trial uses, it suddenly required me to register. The registration was still "free" but that really threw me off.

    In any case, considering the sizing for our application was correct, I put three criteria for my search.
    1. single zone ductless wall mount unit
    2. rated capacity @47℉ greater than 16000
    3. max capacity @5℉ greater than 19000
    There were 454 heat pumps satisfying these criteria. Then I sorted the result in descending order of HSPF rating. The Mitsubishi FS 15000 BTU unit that was suggested by the first and so far only installer is 16th on this ranking. Some units on the list are a larger 18000-BTU rated units.

    There are several models of Fujitsu units and the spec numbers are very impressive compared to the Mitsubishi FS unit I was quoted. Of course, since our Winter 99% design temperature is said to be -17℉ for our region, even the most extreme low-temperature heat pump is going to struggle during the coldest days and hours of our winter. But I am definitely going to ask the installer if they can use the Fujitsu unit instead of Mitsubishi.

    upload_2022-7-1_8-5-45.png
     
    #63 Salamander_King, Jul 1, 2022
    Last edited: Jul 1, 2022
  3. Louis19

    Louis19 Junior Member

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    I chose a Fujitsu after watching the seminar ref post no 62 and consulting the NEEP data base here is the PDF of the NEEP regarding my machine
     
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  4. bisco

    bisco cookie crumbler

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    guys,
    without getting into technical details, since you all have covered them so well, is this worth converting in the boston are from oil?
    i think we're locked in at $5./g this year, but who knows what the future holds.

    the problem is, electrons are in the 25-30 cent range, and will probably continue to go up.

    we have radiant heat, and the only ductwork is high speed a/c.

    typical winters are around 20f, with a few days here and there down to 5f or so, and some in between.
     
  5. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    If you are thinking of converting to a ductless, I'd say flat yes. You will save money and be comfortable.

    If it is a ducted system? Maybe. The principal argument in favor of the ductless over the ducted is that it is really easy for an installer to accidentally make a poor choice while designing and building the ducts, and then all your efficiency is lost before you even turn it on. Something as dumb as being out of stock of one duct part and substituting another just so they don't have to come back and finish on Monday is enough to materially affect the performance for the life of the system.

    The ductless mini-splits aren't subject to this because they are more like appliances. If you get it installed and working at all, it will deliver the performance listed on the charts.

    I'm not getting rid of my oil system. I still expect it to be my heat on the coldest days. Also I can run the oil burner on my backup generator- can't do that with heat pump unless I get a much bigger genny. I just want to use it less, maybe only a tankful a year.
     
    #66 Leadfoot J. McCoalroller, Jul 1, 2022
    Last edited: Jul 1, 2022
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  6. bisco

    bisco cookie crumbler

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    thank you,
    you could never do regular ductwork in this old cape. even when the walls were open, the basement beams and lack of first floor walls made it next to impossible.

    if it wouldn't work with the 2" high speed ducts, i would go with the mini split.

    i could also keep the boiler and radiant/radiators as back up, and it also runs on my 12 kw propane generator.

    sounds expensive though. our layout is cape style with open kitchen/dining, separate l/r back hall with 1/2 bath and laundry leading to mbr behind the garage and en suite bath, both with 12' ceilings.
    upstairs, just two bedrooms.
     
  7. Louis19

    Louis19 Junior Member

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    Tricky question,oil prices vs electricity rate , how about doing an energy lost analysis with thermography of your house.
    It's not feasable to go with duckless if your house is leaking like a pierced bucket.;)
    If you know the heat lost of your home you will have a better picture:rolleyes: and be able to juggle with oil prices vs electricity rate. Here in Canada replacing fossile fuel furnace by electricity is partly subsidised granted you do an energy lost analysis complying with the recommendation report. p.s the test also pressurize the house to evaluate enrgy losses leakage
     
    #68 Louis19, Jul 1, 2022
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  8. bisco

    bisco cookie crumbler

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    thanks,
    how does energy loss influence each type of heating?

    i know that the first floor walls were all updated, and second floor knee walls, but the cape roof leaks like a sieve up until the attic, where the insulation was updated. i could have some insulation blown into the roof.
     
  9. Louis19

    Louis19 Junior Member

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    Pressurising the house is one of the ways to evaluate the lost. Since heat generated by a heatpump is lower in temperature than an oil furnace , any important heat lost will be detrimental to your confort
     
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  10. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I want to hire somebody to do this for my house immediately. Can't find anyone who does it near me.

    Well, I did find exactly one guy, but as soon as I emailed him he thought I was a spammer and offered a remarkably unprofessional response. So now I'm likely to get my own flir camera and just learn it for myself.
     
  11. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I've got that in the works right now. A lot of the comfort factor from heat pumps is predicated on a fairly tight, well-insulated home.

    The thing that can take some getting used to- you will almost never feel warm air coming out of the machine. You get extreme efficiency by only adding the heat a little at a time. Set your thermostat to 70°F? The machine will put out 71° air, and eventually your room will be 70°F.

    If that's your front hall and you keep opening the door every 5 minutes, it will feel cold and the machine will struggle to keep up. Same if it is drafty or underinsulated.
     
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  12. Zythryn

    Zythryn Senior Member

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    Have you tried your utility?
    In our area, the home energy inspectors were created by the utilities.

    Edit*************
    I found this link which may be helpful??
    PA Home Energy Audit | FEPA

    Here is a ‘big picture’ link with references directly from the state of PA.




    Measure Your Energy Usage


     
    #73 Zythryn, Jul 1, 2022
    Last edited: Jul 1, 2022
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  13. Louis19

    Louis19 Junior Member

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    You are right when you say that heat is happening slowly but still it is happening , I measured the coil temp with an infrared thermometer after a defrost cycle , the coil reached127 deg F ...it was -12F outside so with not draft in the house and well insulated it is very cosy inside:)
     
  14. Salamander_King

    Salamander_King Senior Member

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    For your reference, here is the current cost comparison for heating fuel price per Million Btu for our region. The cost of fuel you indicated is very close to ours, currently Heating Oil ($5.36/gallon) vs Electricity (20.9-22.9 cents/kwh).

    At current fuel prices, the oil will cost ~70% more compared to an efficient heat pump. Just a few years ago when the oil price was $1.31/gal, I had no incentive to use electricity to heat our house. But for this winter, if the price of oil stays as high as it is now, then all a sudden electric heat pump is starting to look attractive even with added upfront costs of purchase of the units and installation.

    upload_2022-7-1_14-2-11.png
    source: Heating Fuel Prices | Governor's Energy Office

    Note that the calculation for the Electricity - heat pump use (7.13-7.82 cents/kWh) is based on the COP (Coefficient of Performance) 2.6-3.2 which may not be achievable at very low temperatures for us with 99% design temperature of -17F, but certainly possible for a house in Boston with 99% design temperature of +5F.

    Using the NEEP reference site @Louis19 shared with us I checked for single-zone ductless wall heat pumps with at least 16000BTU rated capacity at 47F and 19000BTU max capacity at 5F, here is the list of units having higher than 2.6 COP at max capacity @5F.

    Screenshot 2022-07-01 2.23.51 PM.png
     
    #75 Salamander_King, Jul 1, 2022
    Last edited: Jul 1, 2022
  15. Louis19

    Louis19 Junior Member

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    :);)
    Home energy Audit that is the way to go .....
     
  16. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Thanks! That led to a full voicemail box. I'll see if an email goes anywhere.
     
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  17. Salamander_King

    Salamander_King Senior Member

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    Heat lost is energy lost. I would think it affects all types of heating equally. If your house is not well enveloped and insulated, then no matter what type of heating you use, you are going to be wasting fuel.

    We had additional insulation (blown loose cellulose) put in our attic to make it R-64 several years ago. It had an R-34 double depth fiberglass batt for insulation. Before and after the additional cellulose insulation, we saw a reduction of ~30% oil usagage during the heating season. We couldn't do much about the wall spaces, so our external 2x6 walls with fiberglass batt R-19 are as far as we can go without ripping the walls and redoing with closed-cell foam insulation which has a higher R-value than fiberglass batt. For new constructions, our state's new regulations which went into effect July 1, 2021, now require a minimum of R-25 in walls for all municipalities. Some cities put even more stringent requirement with a minimum of R-30 in walls. But for our and most houses the windows are the weakest spot for the insulation value. Our double pane windows are R-2.0 far cry from the wall insulation of R-19. This number, even if I spend thousands of dollars for the highest R value triple pane windows, will be around R-3.0. Yeah, if you really want to heat the house efficiently, then build a windowless airtight box. But who wants to live in a dark box???

    For this winter, I'm thinking of applying weatherproof air barrier plastic wrap on the both outside and inside of all windows. Yep, it will look ugly... and I will lose the ability to open the window. But that should increase the R-value at least close to 4. The question is... would the money saved on fuel costs by doing this be worth the cost of the materials and effort? I don't know for sure...

    upload_2022-7-1_15-58-37.png
     
    #78 Salamander_King, Jul 1, 2022
    Last edited: Jul 1, 2022
  18. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Yes, but most fossil burners and some electric baseboards have enough reserve capacity that you won't be uncomfortable. You're only wasting energy. With a heat pump, it isn't too hard to get outside the recovery envelope.

    Then you're wasting less energy, but probably not feeling comfortable while doing it.
     
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  19. Zythryn

    Zythryn Senior Member

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    I don't think that assumption is accurate.
    We don't have ASHP, however, the heat from them, as I understand it is no less comfortable than any other.

    That said, saving energy is saving money, so even if you make updates that make your house waste less energy, and don't change your heat source, you are coming out ahead.
     
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