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4,000 Sq/ft House Costing $800/month in Propane

backwell
backwell Member Posts: 1
Hey guys, I am buying a house that is just under 4,000 sq/ft. The previous owners built the house and they put radiant in floor pex heating everywhere in the property. The basement, garage, all rooms, etc. They said that it was costing them $800 a month to heat the place though.

They are using an on-demand boiler, particularly a Navien T creator. My assumptions here is that the on demand boiler is running non-stop and a tank system might be better in this case. I brought this up to the previous owner and they stated that the system isn't typical in floor radiant. Everything is zoned though so I don't know what could be different about it. There is an option to hook in a wood boiler too and they did that but they were burning 40 cords of wood and still blasting through propane to keep it warm. Any suggestions? House is new and fully insulated.

Comments

  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,533
    What is your location? This system should be checked over by one of the contractors listed here under the find a contractor button.
    If the system had been improperly installed, it could be losing a lot of heat to the ground, or a bad control system could be running a snowmelt system when not needed.--NBC
    GordyRich_49GreenGene
  • Gordy
    Gordy Member Posts: 9,514
    edited July 2016
    Not enough information.

    800 bucks a month for 4000 SF sounds very high. However what was the price of propane?

    Dead give away 40 cords of wood a winter. To assist the radiant. So i assume the boiler was used also.

    Where is the house located? How well is it insulated? How much glazing?

    You need to find out what type of in floor radiant with in the home. Obviously the garage, and basement the tubes are in concrete. The big question is were those slabs properly insulated?

    As for the home there are several radiant floor detail options. Some more efficient at their delivery than others. Some can deliver more btus than others. Again insulation is crucial to performance.

    Find out water temperatures used in the radiant system. Supply water temp to emitters used will say a lot about how well the system was designed. The lower the supply water temp the better. 120 degrees as a medium guide. if they are using 160 then the design is flawed. Especially if it can't keep up with the heat loss.

    Find out if plates were used for the house radiant. You have the advantage that the owners built the house. Hopefully they paid attention.

    As Nicholas said your money would be well spent if you are a serious buyer to find a Radiant heating Proffesional to analyze the total package. Envelope, and all. Go to find a contractor on this site. You need someone fluent in radiant heating. That's not just a plumber,

    To me a red flag is "not typical" in floor radiant.

    if a wood boiler, and a gas boiler is not keeping the house comfortable. Many things could be wrong. Anything from nearer boiler piping to the radiant loops themselves.

    SWEIRich_49
  • Paul Pollets
    Paul Pollets Member Posts: 3,451
    Something is very wrong here. A modulating boiler should have far lower monthly costs to operate, even if your home location has a low design temps. A well trained radiant pro should be able to find out why.
    GreenGene
  • SWEI
    SWEI Member Posts: 7,356
    Is your model listed here by chance?
  • GreenGene
    GreenGene Member Posts: 290
    edited July 2016
    ...........The basement, garage,............

    hmm.......driveway, sidewalks too?

    agree with above statements......something is seriously wrong, first guess would be the radiant is heating the planet below the foundation and not the house

    and 40 cords has to be an exaggeration, 4? 14 maybe? I can't even move or split 40 cords
    kcopp
  • GreenGene
    GreenGene Member Posts: 290
    how much wood would a woodchuck chuck if a woodchuck could chuck wood ? ........42 cords of wood
  • Rich_49
    Rich_49 Member Posts: 2,662
    1 true cord of mixed hardwood is app . 14 million BTUs .

    14,000,000 x 41 = 574,000,000 BTU

    574,000,000 / 4000 sf = 143,500

    143,500 / 2500 hours = 57 BTU sf

    Never took the gas into account . You've got a serious problem . One that can surely be addressed by someone with a clue .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • JUGHNE
    JUGHNE Member Posts: 9,231
    edited July 2016
    If the "cord" of wood is what I was always led to believe, which is tightly stacked 8' long 4' high and 4' deep.
    I would buy the propane rather than move that much wood.

    If the radiant in the concrete on grade is not insulated you may not be able to correct that design flaw.......if the basement floor is well below grade, has radiant tubing and not insulated below that might be tolerated..........if the radiant under wood floors is a bad staple up job without proper insulation that may be corrected by tearing down the ceiling under the floor.

    Is the purchase a done deal yet??
    GreenGene
  • GreenGene
    GreenGene Member Posts: 290
    JUGHNE said:

    If the "cord" of wood is what I was always led to believe, which is tightly stacked 8' long 4' high and 4' deep.
    I would buy the propane rather than move that much wood.

    If the radiant in the concrete on grade is not insulated you may not be able to correct that design flaw.......if the basement floor is well below grade, has radiant tubing and not insulated below that might be tolerated..........if the radiant under wood floors is a bad staple up job without proper insulation that may be corrected by tearing down the ceiling under the floor.

    Is the purchase a done deal yet??

    aye, if not a signed contract walk away or have them get an engineer to look over the house and their plans

    they did have plans, drawings, blueprints, etc when building eh?
    kcopp
  • GreenGene
    GreenGene Member Posts: 290
    radiant should be more efficient than the same home with hot water baseboard, a lot more, you should be doing $800annual
  • SWEI
    SWEI Member Posts: 7,356
    edited July 2016
    We have a client with a ~3,000 ft² house. It has decent passive solar features and six inch SIP walls (R-41 or so.) Her winter propane bills have hit $700 per month several times. Radiant floor heat fed by a massively oversized Vitogas 050. I spent a couple of hours with the IR camera and used a wire to probe exploratory holes drilled with a rotohammer. Turns out she has neither slab edge nor perimeter insulation. They held the tubing back 18" from the edges thinking that would fix it. Truly sad.
    GreenGene
  • GreenGene
    GreenGene Member Posts: 290
    $6000 annual???????????

    I'm doing like $800, 2800 sqft, 1972 construction, System 2000, oil


    no way $6000
    Hatterasguy
  • GreenGene
    GreenGene Member Posts: 290
    Radiant is low temp, low temp = less btu required to heat home = less money.


    You need to get a pro out there.

    kill the garage, basement loops if need be, you are heating the planet Earth below your slab
  • jumper
    jumper Member Posts: 1,755
    Least worst solution may be to abandon the heating system.When it's good,floor radiant is very good.But when it's bad....

    Make the vendor adjust purchase price. You can still use the same boiler with heating panels.
  • Jamie Hall
    Jamie Hall Member Posts: 17,725
    You have to be losing a tremendous amount of heat somewhere. That's about what it costs to heat the ark I care for with $3 per gallon oil, but that is 7,000 square feet, built 1810 to 1893, no insulation to speak of, and draughty in addition.

    Try to figure out where the heat loss is. It may or may not be fixable.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    SWEI
  • hot_rod
    hot_rod Member Posts: 15,378
    JUGHNE said:

    If the "cord" of wood is what I was always led to believe, which is tightly stacked 8' long 4' high and 4' deep.
    I would buy the propane rather than move that much wood.

    If the radiant in the concrete on grade is not insulated you may not be able to correct that design flaw.......if the basement floor is well below grade, has radiant tubing and not insulated below that might be tolerated..........if the radiant under wood floors is a bad staple up job without proper insulation that may be corrected by tearing down the ceiling under the floor.

    Is the purchase a done deal yet??

    Energy from firewood depends a lot on the species, the moisture content, and how it was combusted.
    Wet or green wood burning in a non gassing type stove or boiler may only turn 30% of the energy into useful BTUs.
    So that 40 cords, if they were full cords could equate to a lot of smoke and not much heat energy into the building.

    Garage heating can be a huge load in itself with leaky overhead doors and uninsulated slabs.

    Need to do some load calculations and blower door testing.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Rich_49
  • GreenGene
    GreenGene Member Posts: 290
    Nope, something is wrong with that calculation, the math is skewed or something.

    If the house loses 80k to heat thats all you need, my house is like 86 and my indirect is 88, my boiler is dialed in to 90 and my hot water is on priority. I don't need or want 180k
    Hatterasguy
  • Paul48
    Paul48 Member Posts: 4,470
    @GreenGene

    "Radiant is low temp, low temp = less btu required to heat home = less money"

    Really?
    GordyGreenGene
  • Gordy
    Gordy Member Posts: 9,514
    Gentlemen there is barely enough information in the original post to even begin to asertain the situation.

    We don't know the geographic location. Yellow knife Canada, or Miami Florida....

    We don't know what the owners were trying to keep for an indoor temp.

    We don't know if the boilers cycle to death off high limit, or run flat out.

    We can only begin to guess the radiant details. We all know how many tangents that can take.

    To,answer the OP's direct question on whether a tank style boiler which could mean a buffer tank, water heater (which is NOT a boiler) or something like a Phoenix HTP product would to elevate the pain.


    My answer is no until some details can be ironed out.

    Pictures would help us a lot. Everything pertinent to the heating system.


    Is 800 dollars a month heating bill possible, and or exceptible with propane at 3-4 bucks a gallon for 4000 SF. Sure it can be it depends.

    Burning 40 cords of wood, and propane together. 10 cords is a pretty good jag of wood for 4000 SF with a gasification boiler set up right.

    I suspect things are not right what is the question.
    SWEI
  • Gordy
    Gordy Member Posts: 9,514
    SWEI said:

    We have a client with a ~3,000 ft² house. It has decent passive solar features and six inch SIP walls (R-41 or so.) Her winter propane bills have hit $700 per month several times. Radiant floor heat fed by a massively oversized Vitogas 050. I spent a couple of hours with the IR camera and used a wire to probe exploratory holes drilled with a rotohammer. Turns out she has neither slab edge nor perimeter insulation. They held the tubing back 18" from the edges thinking that would fix it. Truly sad.


    Was this a slab on grade Kurt?
  • SWEI
    SWEI Member Posts: 7,356
    Yes, and allegedly some blue board under the middle portion of the slab. No info on the thickness used. The GC ran off before the job was finished and was eventually convicted of defrauding multiple homeowners.
    Rich_49
  • Gordy
    Gordy Member Posts: 9,514
    Figures.
  • Rich_49
    Rich_49 Member Posts: 2,662
    A BTU is a BTU regardless of temp Gene .

    Maybe you could tell us what is wrong with Hatteras Guy's math . If you see something you should certainly be able to point said thing out for the rest of us .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    GordyHatterasguy
  • rick in Alaska
    rick in Alaska Member Posts: 1,269
    I am heating 2400 square feet with all radiant. Top floor hardwood over sleepers and gypcrete, and bottom floor slab on grade, with r10 under. Also heating a 60 gallon indirect.
    House is r34 in walls and r50 in attic. I take hot showers every night and keep the heat at 68. No sweaters for me in my house! Last I checked I am running about 45 gallons of fuel oil a month.
    At about $3.80 per gallon, last I remember, it works out to $2052 per year. I think we are at something like 9000 degree days, but not sure.
    Just an fyi.
    Rick
    GordySWEInjtommy
  • GreenGene
    GreenGene Member Posts: 290
    edited July 2016
    Paul48 said:

    @GreenGene

    "Radiant is low temp, low temp = less btu required to heat home = less money"

    Really?

    think about it

    radiant in the floor uses lower temperature than baseboard, the home may have load calc of X but you are going to use less energy (ie btu's) because you don't have to heat the water to 180F, you only need 90 or so in the floor, it's cheaper to run, more expensive to install

    most studies show radiant to be 30% more efficient, add to that you won't have issues with stratification, humidity, and you'll feel warmer at a lower temperature

    of course this is all based on the system being designed and installed correctly and you must use the manufacturer's design program for their product and follow their instructions to the letter regarding tubing size, spacing lay out and insulation

    all of which may be at the core here
  • hot_rod
    hot_rod Member Posts: 15,378
    GreenGene said:

    Paul48 said:

    @GreenGene

    "Radiant is low temp, low temp = less btu required to heat home = less money"

    Really?

    think about it

    radiant in the floor uses lower temperature than baseboard, the home may have load calc of X but you are going to use less energy (ie btu's) because you don't have to heat the water to 180F, you only need 90 or so in the floor, it's cheaper to run, more expensive to install

    most studies show radiant to be 30% more efficient, add to that you won't have issues with stratification, humidity, and you'll feel warmer at a lower temperature

    of course this is all based on the system being designed and installed correctly and you must use the manufacturer's design program for their product and follow their instructions to the letter regarding tubing size, spacing lay out and insulation

    all of which may be at the core here
    But Gene, it takes X amount of heat to overcome the building loss, no matter how, or how efficiently you add it.

    Now you can have less fuel useage associated with higher efficient equipment, or more efficient distribution methods, but the load is the load.

    Reducing the heat load # would require upgrading the building envelop.

    Or change the weather.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Rich_49
  • GreenGene
    GreenGene Member Posts: 290
    edited July 2016
    Input of our equipment is measured in btu's, radiant takes less input

    I didn't mean the building's heat load was different, you will use less energy with a properly engineered and installed radiant system than most other systems by 30% or so.

    If everything is the same no matter what it wouldn't be possible to save energy.

    except apparently this house, questions are

    Did the homeowner build the home themselves and did they design install the radiant system themselves and what methods did they use?

    Something is seriously wrong here, the only homes I have seen in the sq ft range that had 6-8,000 in heating bills had electric heat in Ct.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,217
    Well, you really need to give us more information before we can really give you any meaningful assistance.

    One thing is definite. You are burning a lot of fuel and the heat is going somewhere. The ratio of heat going into you living space versus the heat being lost cannot be determined at this point.

    Being that this is the middle of the summer and you likely aren't using much heating, it is not the best time to do much homeowner sleuthing.

    Here is where you should start though. Hire a professional to come into your home and perform an acruate heat load calculation. Your system in it's entirety is based or should be based off of this number. Once you have that you can determine just how much heat is being wasted and start looking for it.

    One thing I would scrutinize in great detail is how your wood boiler is tied into the system. Assuming it's an outdoor boiler, how many feet of underground piping to the house? What type of piping is it and how are the ends terminated? Is it possible for water to enter the outdoor end? Might the piping have a compromised shell, allowing water to saturate the insulation? How are the controls setup to bring water in from the house? Is the circulator setup to run constantly? Do you have a temperature drop in the water between the wood boiler and the indoor boiler? If so, how much and what model pump is on it?
    Unfortunately, there are a great many subpar wood boiler installations which is what would make me want to look at that first.

    Whatever the problem may be, we can definitely help you with it if you are willing to answer questions and follow advice.
    SWEI
  • GreenGene
    GreenGene Member Posts: 290
    edited July 2016
    I think you're getting ahead of the game.

    1 question Was the radiant installed correctly and insulated underneath???

    if NO the garage and basement are useless and should be abandoned, the rest may be ok.

    The plans and heat loads need review and the people that installed it need to be interviewed as to what they did under the floor.

    If all they did was wing it.........game over

    we don't even know this is a true story, someone posts they are buying a home with radiant and wood and use $6000 in fuel and 40 cords????

    slightly unbelieveable
  • GreenGene
    GreenGene Member Posts: 290
    edited July 2016
    40 cords of wood is over 5000 sq ft, who the hell is going to split all of that, or buy it?

    and that would be tightly stacked wood, a loose stack would be 7200 sq ft........maybe in 1783 then it could be 30-40 cords.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,217
    ""I think you're getting ahead of the game.

    1 question Was the radiant installed correctly and insulated underneath???""

    Perhaps?
    Personally I would rule out the easy things first before I started probing Concrete and such.
    But that's just me.
  • GreenGene
    GreenGene Member Posts: 290
    edited July 2016
    That is the easy thing,

    First thing find out if it can even work before doing anything.

    I'm not buying the $$ and cords.

    no simple adjustments are going to correct those numbers
  • hot_rod
    hot_rod Member Posts: 15,378

    Well, you really need to give us more information before we can really give you any meaningful assistance.



    One thing is definite. You are burning a lot of fuel and the heat is going somewhere. The ratio of heat going into you living space versus the heat being lost cannot be determined at this point.



    Being that this is the middle of the summer and you likely aren't using much heating, it is not the best time to do much homeowner sleuthing.



    Here is where you should start though. Hire a professional to come into your home and perform an acruate heat load calculation. Your system in it's entirety is based or should be based off of this number. Once you have that you can determine just how much heat is being wasted and start looking for it.



    One thing I would scrutinize in great detail is how your wood boiler is tied into the system. Assuming it's an outdoor boiler, how many feet of underground piping to the house? What type of piping is it and how are the ends terminated? Is it possible for water to enter the outdoor end? Might the piping have a compromised shell, allowing water to saturate the insulation? How are the controls setup to bring water in from the house? Is the circulator setup to run constantly? Do you have a temperature drop in the water between the wood boiler and the indoor boiler? If so, how much and what model pump is on it?

    Unfortunately, there are a great many subpar wood boiler installations which is what would make me want to look at that first.



    Whatever the problem may be, we can definitely help you with it if you are willing to answer questions and follow advice.


    Good point on the wood boiler tie in. I've seen where the fossil fueled boiler is sending heat out to the unfired wood units, basically a cooling tower :) That will run up a fuel bill quickly.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Rich_49