Number crunching

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

  1. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,822
    4,754
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    We are about a year into owning the two cars we hope to keep, the Prius c and a Mazda 6.

    I crunched some numbers and found some interesting bits.

    • We were successful in stacking more than 80% of the household total miles driven onto the Prius.
    • We only would have saved another $250 by forgoing the comfort and cargo space gained by adding the Mazda to our fleet for the past year.
    • If we only had the Mazda, our household fuel costs would have been close to double for the year.
    And the biggest bit that stands out: we are still buying more petroleum to heat our home through winter than we are for mobility.

    That's a cheaper problem to work on, for now.
     
    jerrymildred and John321 like this.
  2. Mendel Leisk

    Mendel Leisk Underfoot

    Joined:
    Oct 17, 2010
    48,338
    34,523
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    How's the insulation, gap-sealing, windows/doors?
     
  3. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,822
    4,754
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    We've found the insulation to be poorer than we initially understood. I've been talking to a crew about blowing in a fresh blanket o bits.

    Windows are the good news, former owner replaced all except the 4 newest. Fairly generic vinyl double-pane, much tighter than the originals.

    I want to install a big minisplit heat pump rig for 4 season service.
     
    Mendel Leisk likes this.
  4. Mendel Leisk

    Mendel Leisk Underfoot

    Joined:
    Oct 17, 2010
    48,338
    34,523
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Central heating ductwork is another thing to look into, both the heated and return. Ours was disastrous; the return side in particular had some bizarre shortcomings. Found bits of 2x4 dumped in some of the heating ducts (by the 1980's "carpenters"). Sealing/tightness of both circuits was abysmal.
     
  5. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    2,464
    893
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    As a home ages its exterior shell gets less and less weather resistant, mostly from expansion and contraction.
    The original wet wall of out 100 year old house leaks drafts like a sieve and it's on the opposite side of the house that faces the prevailing winds in our area. I've tightened it up some where I can access it from inside, but I'd much prefer to reside the present 3 layers of siding on that side of the house.

    Have any of you ever seen a 2x8 rough sawn floor joist notched 5 to 6 inches by a remodeler? I had two of them. I fixed one by sandwiching 3/4 in ply on both sides of the notched joist, glueing and 3in screws.
    I still have one to do, but it'll hae to wait for a new tub first. Don't get me started on the other plumbing and electrical code violations form that remodel job, I've been chipping away at for years now. :coffee: please
     
  6. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,318
    8,218
    0
    Location:
    New England
    Vehicle:
    2021 Prius Prime
    Model:
    Limited
    Yeah, the "comfort" aspect can be a huge factor in selecting a car especially if the price of comfort is relatively cheap. I'd much rather drive 24mpg SUV for my long trips for its comfort aspect, but that means I will be using an almost triple the amount of gas than driving the PP. When the gas price was below $3, that would have been only ~$50/trip. For a small number (less than 5) trips, I have chosen comfort over the economy.

    The same for our household even before moving to hybrid vehicles. We have always used more oil in heating than total gas used for transportation each year. What is hurting most now is that historically in our region, the #2 heating oil price has been cheaper than the local gasoline price at any given time period. The current situation has changed all of that. Ever since the hike in the crude oil stemming from the Ukraine war increased the gas and heating oil prices, the heating oil price has been remaining much higher than the local gas price. The last year when I fill the heating oil tank, I paid only $2.80/gal for heating oil while the gas price was already ~$3.30/gal. But just last month, the #2 heating oil was $4.72/gal when the gasoline price just hit the $4.00/gal mark. I just called my oil company and asked for the current heating oil price. The price has increased in the last 1 month, now stands at $5.20/gal while the local gasoline price has come down to $3.90/gal.
     
    #6 Salamander_King, Apr 22, 2022
    Last edited: Apr 22, 2022
  7. John321

    John321 Senior Member

    Joined:
    Nov 16, 2018
    619
    713
    0
    Location:
    Kentucky
    Vehicle:
    2008 Prius
    Model:
    Two
    One aspect of my job was to help manage energy cost of our facility and you quickly realize that Heating/Cooling are where the most money is spent. You apparently did a very good job of collecting data and highlighting where your energy dollars where going. Data collection was the first step we used to highlight our biggest energy users and then develop Kaizens to lower energy consumption.

    We built out house 7 years ago and I paid particular attention to the selection of the Heating/Cooling unit for our home knowing this would be the source of our highest energy cost.

    We went with a Hybrid system - Heat Pump coupled with a 98% efficient furnace. At moderate temperature the Heat Pump provides efficient heat, at lower temperatures the High Efficiency Gas Furnace takes over. Both the air handler/furnace and Heat Pump have variable speed blowers/compressors and this does a good job at keeping the home comfortable and cost down. With the Hybrid System you can change the cut in settings for gas or electric systems base on the cost of these fuels.

    Another fuel savings tip if you have an Electric Water Heater is to switch to a Heat Pump Water heater. These are initially more expensive but many Utility Companies will actually supplement your purchase price when you buy one.

    I should have mentioned our Gas Utility and Electric Utility gave us rebates to help purchase our Heating/ Cooling System because they met their High Efficiency requirements for rebates, maybe your Utillity will offer similar rebates.

    Good luck on your energy savings journey- a wonderful thing about energy savings is once implemented they continue to pay dividends to you day after day.
     
    #7 John321, Apr 22, 2022
    Last edited: Apr 22, 2022
  8. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,822
    4,754
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    No ducts at all here. It's an oil fired baseboard heat setup. Works great, and I'm inclined to keep it as a backup system because it can operate on very little electricity. Well within the envelope provided by cheap standby generator or solar inverter.

    We already installed a ductless minisplit AC with heat for the upstairs bedrooms. Now I want a bigger version of same to do the downstairs living spaces. I want that to become the primary heat for the home.

    Our domestic hot water is also heated by the oil burner. I would really like to change it over to a heat pump. I haven't been able to find anyone willing to install one.
     
  9. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    99,291
    44,974
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    oil heat and hot water are by far our largest fossil fuel use, even when we were working.

    since retiring, i've had to notch the thermostat up a degree every year on my birthday :cool:
     
  10. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

    Joined:
    Nov 3, 2012
    3,208
    1,400
    0
    Location:
    Sanford, NC
    Vehicle:
    Other Hybrid
    Model:
    Three
    Don't discount an in-ground geothermal system. My cross the street neighbor had one installed. Massive savings. His is vertical but another guy who built a house has a horizontal field.

    Something I have never understood is why in the South they run duct work in the attic. Guaranteed to be both the hottest and the coldest location possible and blows air of the wrong temperature on start up. Why are my chairs always under the vents?
     
  11. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    2,464
    893
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    I've never heard of a heat pump that provide a homes hot water. Unless the homes hot water demand is really low, other wise the heat pump would have to be way oversized and not too efficient for normal hot water demand.
    I've been thinking about a tankless job with a manifold to add supplemental radiant heat, but my 20 year old gas water heater is still hangin in the there - fingers crossed behind my back.
     
    #11 vvillovv, Apr 24, 2022
    Last edited: Apr 24, 2022
  12. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,822
    4,754
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    Screen Shot 2022-04-24 at 6.17.19 AM.png

    Screenshot of typical unit for sale at big box down the way.

    It's an electric hot water heater with a window A/C sized heat pump sitting on top.

    If your hot water demand isn't all at once, the thing has plenty of time to heat all your water from the ambient air in your garage or basement. Plus you get free cool air for garage/basement.

    If you exceed what the heat pump can heat, the regular resistive elements kick in and you're then no worse off than a regular electric water heater.

    Difficulty: all the plumbers in my area hate them, haven't found anyone willing to install one.

    I don't especially want one if it's going to be problematic but... they can't all be that bad, can they?
     
    John321 and vvillovv like this.
  13. John321

    John321 Senior Member

    Joined:
    Nov 16, 2018
    619
    713
    0
    Location:
    Kentucky
    Vehicle:
    2008 Prius
    Model:
    Two
    The one in your picture Is from AO Smith and has an excellent reputation.

    Our unit is a GE Geosprings Unit. that is no longer made. The cost savings over an old style electric are dramatic. The only difference in the installation over a traditional unit is a line from the Heat Pump Section to drain condensate. Ours is installed in the basement and it make a noticeable difference in reducing the Humidity in the basement.

    A Heat Pump Water Heater Is The Energy Saving Equivalent Of 7 Solar Panels & Costs ⅙ the Price - CleanTechnica

    The ducting in the picture is unnecessary - ours is installed with none.

    Our builder initially refused to install a Heat Pump Water Heater and I had to get into an uncomfortable conversation with him about how he was going to have to do it. Afterwards when he saw how easy the installation was he apologized and had a lot of interest in its operation.
    Here is our install Hybrid Heat Pump Water Heater:

    Hybrid Hot Water Heater.jpg
     
    #13 John321, Apr 24, 2022
    Last edited: Apr 24, 2022
  14. Trollbait

    Trollbait It's a D&D thing

    Joined:
    Feb 7, 2006
    18,233
    8,967
    0
    Location:
    eastern Pennsylvania
    Vehicle:
    Other Non-Hybrid
    The ducting may not be necessary, but it will let you move the cold air by-product to where you want or not want it.

    Heat pump hot water can also be had as an addition to a HVAC heat pump. During periods when the A/C is on, these are using waste heat.
     
  15. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    2,464
    893
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    If replacing an Electric water heater, than sure, spend the extra $ upfront and enjoy the benefits that you'll get from the heat pump. There are always scenarios where one is a better choice than another for very specific reasons. It's not simply a one answer fits all situations.
    A link that might help explain some of the differences between a natural gas fired water heater and electric water heater with a heat pump, from a Plumbing / Electrical contractor that installs both.
    https://georgebrazilplumbingelectrical.com/heat-pump-water-heater-vs-gas-water-heater-which-is-better/
    Yes, I learned some new stuff too. ;)
     
  16. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,318
    8,218
    0
    Location:
    New England
    Vehicle:
    2021 Prius Prime
    Model:
    Limited
    When we had asked a solar installer company to do a total energy conversion analysis. Not only did he come up with the solar panel installation, but also heat pumps for heating and water heating. Fou our current house, similar to OP's house, has no ducts. An oil-fired boiler sends hot water to baseboard radiators in each room. And hot water is also heated by the oil boiler on demand. It was a tankless hot water heater within the boiler, but we have retrofitted a small 40 gal indirect heat exchanger storage tank after scaling from the hard water destroyed the small heat exchanger. It was a good upgrade since the storage tank would allow the boiler to finer less frequently.

    Anyways, we really wanted to total conversion to electric and get rid of the oil boiler. But quickly learned that was financially and technically very difficult. Any heat pump-based heater would be only able to heat part of the house part of the year, not during the coldest months. It will save some oil usage, but it is not likely to save any money in the end since our electricity rate is so high. Similarly, the heat pump water heater conversion is not easy, since we don't have an electric hot water heater. Plus they're just isn't enough room in the basement where currently the oil boiler and indirect water heater are located. In order for the heat pump water heater to work efficiently, it requires a larger area than a conventional water heater would, so I was told.

    So, both heat pump room heater and water heater ideas are quickly abandoned. But now with a hike in fuel oil price, if it remains very high in the near future, I am going to revisit the idea of installing the solar water heater tubes on the roof, and will probabbly install small wood-burning stoves in the other areas of the house in addition to one we already have, unfortunately in a living room that does not get used often enough.
     
  17. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    16,019
    9,205
    90
    Location:
    Western Washington
    Vehicle:
    2012 Prius
    Model:
    Three
    The main issue with ground-source heat pumps is the installation cost of the ground loop. For dad's farmhouse, we put in a horizontal loop in the adjacent hay field, but the excavation cost (even in a deep rural / no permits requirement / low labor cost area) was substantial. And it exceeds the land area most suburban homes have available. Smaller lots need a vertical loop, requiring a well drilling rig.

    Air-source heat pump installation is much cheaper. But in colder climates, ground-source systems definitely outperform air-source. Though note that in the last decade or so, top end air-source systems have made great strides in improving their cold climate performance, becoming the preferred choice in numerous zones that once required ground-source.
    I installed a stand-alone heat pump water heater (HPWH) nine years ago, and love it. It is my second-greatest home energy savings improvement. (A ductless mini-split space heat pump is the first.) Today's HPWHs have much better performance than my old one.

    There are hot water systems integrated with a building's heat pump HVAC. In warm AC-dominated climates, these systems can show extremely high energy efficiency ratings, as each single unit of electric energy does double duty, producing multiple units of cooled air and of hot water.
    For domestic hot water in typical home usage patterns, electric tankless can't possibly match the energy efficiencies of HPWHs. Not even close, even in theory.

    A tankless electric resistance water heater has effectively 100% energy efficiency. This is better than the 80%-ish or lower of older tanked models that suffered much stand-by loss, but not that much better than the 94-96% of modern Energy Star units. But my older Tier 2 HPWH (the best available at that time) was rated at about 200%, while today's Tier 4 models are rated 340% to 400% 'efficient' (and performing even better in warmer climates):
    https://neea.org/img/documents/residential-unitary-HPWH-qualified-products-list.pdf

    Electric tankless still has its niches, such as vacation homes that are vacant most of the time but then need hot water quickly, without much delay, when the whole family arrives Friday night. Or homes that need "endless hot water" without recovery delay, such as multiple teenagers taking very long showers back-to-back. But for real energy efficiency, electric tankless just isn't competitive anymore. Not even close.

    There are HPWHs that can work with radiant heat systems, but this is a smaller market with fewer offerings at higher cost. For this application, look at the split-system models such as SANCO2.
     
    #17 fuzzy1, Apr 25, 2022
    Last edited: Apr 25, 2022
  18. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,822
    4,754
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    Yes that's our set-up here.

    A few different factors:

    • Slightly warmer climate. Not much, but enough to extend heat pump season measurably.
    • Lower electricity cost here
    • I have the space and flexibility to add a water heater like this. It will require some tandem breakers, no empty slots on the panel, but that's not horrible.
    • I have bought electricity to run a dehumidifier in that space in the past... free bonus in the summer!


    So I want some plumbertrician to install this thing in my basement and wire it up properly

    We already have a nice EPA-rated woodburner insert for the original fireplace. Makes piles o heat for about 1/3 of the house. Took me a while to learn to drive it but I can get great heat and zero smoke now.
     
    Salamander_King likes this.
  19. vvillovv

    vvillovv Senior Member

    Joined:
    Mar 19, 2013
    2,464
    893
    1
    Location:
    NY
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Plus
    There's no way I'd ever consider using electric to heat anything in out area, it would double and during colder weather even triple our utility bill, if I switched our natural gas water heater, furnace, range and dryer to electric appliances.
    @fuzzy1 hummm, the 100% 200% 300% efficiency ratings need to be clarified and put into simple terms or they just sound too good to be true, if you know what I mean.
    For instance with a gas furnace, new ones are rated at 95% efficient and above to I think 98%, while 50 year old gas furnaces were typically around 80% efficient. Lot's of new tech in the 95% efficient furnaces reuse waste heat inside the furnace and the burning of the gas like a cars EVAP systems does.

    BUT, Contractors in the past have advertised the new furnaces by saying once the high efficient furnace is installed in the home it will save $1000 or more on the utility bill.
    Not So (unless) it a really huge home that heats the entire space to 78*F or above all winter. For comparison sake, In our 30k sq ft home which only uses around $1000 in natural gas a year even with old tech gas appliances.

    I do conserve as much as possible within the limits the misses dictates and I would like to upgrade, especially the furnace to a high efficiency job to reduce the particulates that escape the lower efficiency furnace in unburnt natural gas.
    But if I turn off the wasteful always burning pilot lighter of the furnace for 6 months it used (O therms) instead of the 15 therms per month that pilot lighter consumes (15 therms of gas = $10 - $15 on out utility bill ). Further, the only reason I believe I still have a 50 year old furnace in the home is because I do all the maintenance myself. If I had to call for service, I'm sure that old job would be long gone by now.
    @Leadfoot J. McCoalroller I'd have a stove in the fireplace too, they are a really nice supplemental heat source in the winter. I still use the old school fireplace once a month, if I'm lucky.
     
    #19 vvillovv, Apr 26, 2022
    Last edited: Apr 26, 2022
    Salamander_King likes this.
  20. Zythryn

    Zythryn Senior Member

    Joined:
    Apr 28, 2008
    5,542
    3,605
    1
    Location:
    Minnesota
    Vehicle:
    Other Electric Vehicle
    Model:
    N/A
    How about, “it takes one unit of energy to move 2-3 units of heat”?
    It is far easier to move heat than to create it via combustion.

    And 30k sq ft house?? That was a typo, right?
     
Loading...