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Fuel use question?

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  • icesailor
    icesailor Member Posts: 7,265
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    When you buy a 20# LPG gas grill tank, it can only hold 15# of liquid. The other missing 5# is for expansion.

    Those quick connect connections that some hate so much are partly an overfill device. There's a float inside that actually shuts off the flow when you try to overfill it. Then, there's a gas flow limiter so you can't draw gas too fast.

    The old illegal tanks could be overfilled with liquid and when turned on to light your fire to cook your steaks on the grill, you and the steaks could be cooked together. That's why there is a mfgr's date stamped into the tank.
  • vibert_c
    vibert_c Member Posts: 69
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    Hey Ice: I disagree with your statement about the net weight of liquid in a 20 pounder. Do some more research or you are like 98% of folks that get ripped off at the depot.
  • BobC
    BobC Member Posts: 5,478
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    I remember a neighbor got my tank refilled when he bringing his down; he knew the guy so he filled it up a little more than normal (these were the old style tanks). I put the tank in my garage as a backup. A couple of days later on a hot day I heard a noise coming out of the garage, I looked through the window and saw the tank venting. The garage is stand alone and there is about a 1" gap at the bottom of the door, i opened the door that evening after it had cooled down and brought the tank out to the yard where I opened the tank to vent more gas.

    That tank was stored out by the back wall under a tarp from then on. That was the day I learned why you don't overfill those tanks.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Gordy
    Gordy Member Posts: 9,546
    edited January 2015
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    vibert_c said:

    Hey Ice: I disagree with your statement about the net weight of liquid in a 20 pounder. Do some more research or you are like 98% of folks that get ripped off at the depot.


    I think you better do a little more research. You might squeeze 18# into a 20# tank. But then you could end up like Bob. Most people are confused by the way propane tanks get filled.
  • JUGHNE
    JUGHNE Member Posts: 11,062
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    Same thing, old style tank filled by good ol' boy to both give max volume for me and max weight for him. The day got hot with grill sitting outside low window. Wind was blowing gas into house, lucky I was home.
    icesailor
  • wrxz24
    wrxz24 Member Posts: 301
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    There was 3% left when the guy showed up and 85 % when he left. He was able to put in 407 gallons.
    Will look into a gas meter.
  • Gordy
    Gordy Member Posts: 9,546
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    They are filling your tank with 425 gal. If at 3% when filled and it took 407 gal. You had 18 gal left.
    icesailor
  • icesailor
    icesailor Member Posts: 7,265
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    All those delivery trucks, whether gas or oil, are required by law to be inspected by a authorized measurer just like every gasoline pump you visit to fill your vehicle. No one suspects that their friendly local gasoline filling station is ripping them off on deliveries. Just look on every pump. There is a signed and certified sticker from the local Sealer of Weights & Measures. It has to be inspected annually or at any time they feel like doing it in between. Oil and Propane companies pay big bucks for all the measuring equipment required by law to be in place. When a oil or LPG truck makes a delivery, they start a new ticket. It reads ZERO, The fill it with an uncompressible product. The only thing compressible is the air/gas in the top of the tank when it gets filled. When your "20#" grill tank is empty, next time you go to fill it, shake the tank back and forth, That thing that sounds like a light chain ratttling back and forth is the float on the overfill valve operating. If you don't have a tank that is within the inspection date, and it doesn't have an overfill protection device or a flow limiting shut off, you have an illegal tank. It isn't supposed to be filled. I went to BJ's a few weeks ago. They were selling 20# cylinders right there on the table, with new gas grills. Although they were advertised as 20 pounders, they only hold 15 pounds. You could fill them right there in the back where they sell and install tires. The tank only allows 15# into it before it shuts off. Because the overfill valve shuts off the valve.

    If you want to worry about something. Nat. Gas is compressible. How well do outside gas meters measure of the mechanism isn't working smoothly? Who's getting screwed? If you build a new house, and have a 1,000 foot driveway to the house. Be sure to put the meter at the road, not at the house. So you can pay for the line loss to the power company. Who have already figured it into the electric rate. Put a meter on the house too. The difference is considerable.

    Those LPG and oil delivery trucks all have up to date measurement and safety inspection stickers on them. If they don't, they get shut down.

  • vibert_c
    vibert_c Member Posts: 69
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    Ice:
    I never yet met a true Scotsman that would accept 15 lbs of propane when he was paying for 20 lbs. You fit into the 98% of folks getting ripped off, in my humble opinion.
    Vibert_C
  • Gordy
    Gordy Member Posts: 9,546
    edited January 2015
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    Personally I still dont know where ANYONE is getting 20 lbs of propane in a 20 lbs. tank. That download you posted says 17.5 which is 85% this would dpend on time of year (temperature).


    Keep in mind there may be a larger saftey factor where these big box stores, and gas stations have tank exchange racks where patrons are going in and out all the time. Not good to have a tank gas off with a smoking patron walking by. Should they be NO, but you know in court it would be if the tank never gased off little jounny would not have blown up.


    A Scotsman would probably be on NG. with a quick connect for the grill off the house piping. OR using wood from a dead oak limb in the yard.

    Surely not go to a tank exchange, and pay for convenience. They don't put those setups in front of stores for free. You pay for it.
    Itallians are worse yet. You have no idea how many 100 year old nails I pulled, straightened, and put into coffee cans to be reused after tearing down an old barn for my moms uncle. Not cheap, but frugal.
  • SWEI
    SWEI Member Posts: 7,356
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    We used to get 90% fills in colder months sometimes - before the OPD retrofits kicked in. Now they fill on a scale, and stop when the designated weight is reached. Paying by the gallon anyway...
    icesailor
  • Paul48
    Paul48 Member Posts: 4,469
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    Are you post pumping for 30 minutes? If so, are you pulling any excess heat beyond 10 minutes?
  • wrxz24
    wrxz24 Member Posts: 301
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    Paul48 said:

    Are you post pumping for 30 minutes? If so, are you pulling any excess heat beyond 10 minutes?

    I used to but now am doing a 10 minute post purge with a 10 minute fire delay. By the time 10 minutes is up, no heat exchange.
    I am still trying to figure out what setting works best for the boiler pump(tt 110) Currently it is on speed one and am getting a good 20 degree delta t at the boiler but the boiler ramps up more as the delta t is wider. On speed 3, the delta t is less 8-14 but the boiler runs at a lower fire as it must be pulling in more water from the boiler. Not sure what would work the best... I have it now, that all my zones are run off one tstat.

  • Gordy
    Gordy Member Posts: 9,546
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    SWEI said:

    We used to get 90% fills in colder months sometimes - before the OPD retrofits kicked in. Now they fill on a scale, and stop when the designated weight is reached. Paying by the gallon anyway...

    True, but you also pay the markup for convenience at the area big boxes, and gas stations for exchange.

    I think that's what people don't understand they think they are paying for 20 lbs, and getting 15-18 when actually your just paying more per gallon. Your paying by the gallon so figure it out where you pay how much it is verses a supplier. They don't deliver fills, pickup empties for free, everyone gets a cut.
  • Paul48
    Paul48 Member Posts: 4,469
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    You need to know how many gpm the system is taking away from the boiler. Then match the boiler gpm(as close as possible) to that. That ensures that all the heat created by the boiler is sent to the system. Don't fixate on delta t's.
    icesailor
  • wrxz24
    wrxz24 Member Posts: 301
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    Good to know, thanks, I do know the system gpm is higher than the boiler gpm at speed one, because the boiler water mixes with the return water at the T's and that water temp is slightly cooler as it goes to the zones. All zones are controlled by one tstat so maybe I will try speed 2 and see if that gets things closer.
    So if the return temp from the zones mixed together and the water entering the return T back to the boiler are close to the the same than that is better than having a high delta t? Because when it is really cold, I get some delta t's in the 30's when on speed 1 and the boiler is firing at full tilt.
  • vibert_c
    vibert_c Member Posts: 69
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    Hey Gordy:
    The 17.5 lbs in the spreadsheet is the TARE weight of an empty bottle. Please study it more carefully especially the WC [water capacity] This is the key to understanding.
    Vibert_C
  • Gordy
    Gordy Member Posts: 9,546
    edited January 2015
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    Actually if you read into the "rip off" gripe. The only reason the exchange bottles have less propane is do to the price difference of the cost of LP. Instead of changing price signs all the time they just vary the quantity to reflect the price actually pretty smart. The only rip off is more trips to exchange tanks I guess.

    You can post all you like, but never have I gotten 20# of propane in a 20# tank. Exchange , or through the local LP supplier. Like SWEI said you pay by the gallon anyway. That's like saying you got ripped off because you only got 4 gallons of gas in a 5 gallon can, and paid for 4.

    If the statement is true then a 500 gal tank should hold 500 gal with proper room left for expansion. If all LP tanks buy design hold the listed quantity with proper room left for expansion. As seen above that's not the case.

    As for me I got off the bottle a long time ago. Most people with NG fail to realize how easy it is to convert their grill, and have some piping done. Same goes for LP.
  • icesailor
    icesailor Member Posts: 7,265
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    "" Ice:
    I never yet met a true Scotsman that would accept 15 lbs of propane when he was paying for 20 lbs. You fit into the 98% of folks getting ripped off, in my humble opinion.
    Vibert_C ""

    I don't know where you buy it, but whenever I bought mine from a LP dealer that filled on the spot, they used a scale. Set the empty tank on the scale, when it hit 15", they shut it off, and you paid for how many gallons went through the meter. Convert liquid weight/Gallon, or liquid gallons to weight. When they drop 150 gallons of LPG into your 250 gallon torpedo tank, it is by gallons. 150 gallons of LPG has a weight. Just like a gallon of water weighs 7.44#.

    When I got the last fill up from B-J's, they did the same thing by weighing it. They charged me by how many gallons they used to fill to that weight.

    If you can go back to grill tanks to 1990, they could stuff 20# into a 20# cylinder if it was dead empty. People were overfilling them on a cold day and leaving them in the sun. They expanded and the relief valve relieved itself. Then, there was the issue of trying to run 200,000 BTU appliances wide open on a 20# grill tank. All those LPG tanks have ICC/DOE stampings and have to be u=inspected. If they go out of date, they can't be filled. Then, sometime in the 1990's, 2000's, they changed the rules and ALL tanks had to have safety overfill devices inside and a quick disconnect fitting that limits the flow of gas out of the tank and will shut it off. If you see a 20# grill tank without the new valve head, it is illegal and can't legally be filled. If the tank isn't out of date, you can change the valve, but there shouldn't be any tanks around now. You can fill them on your own from an inverted 100# cylinder.

    I'm Scotts. The supposed largest Clan in Scotland. Even I draw the line there,
  • icesailor
    icesailor Member Posts: 7,265
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    @Gordy:

    "" Itallians are worse yet. You have no idea how many 100 year old nails I pulled, straightened, and put into coffee cans to be reused after tearing down an old barn for my moms uncle. Not cheap, but frugal. ""

    And when it comes time to need those salvaged nails, you:

    #1: Forget where you put them
    #2: Buy new ones in case you run out.
    #3: Use the new ones first and plan on using the old ones when you run out.
    #4: You never run out of new nails and you save the left overs for the next project.
    #5: You have bags and boxes of nails stored but you can't find the 10d nails and you don't want to waste 16d because you might need them on another project.

    So, that's why you bought new nails for the project.

    Same applies to drive screws.
  • Paul48
    Paul48 Member Posts: 4,469
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    What was this post about?
    RobG
  • icesailor
    icesailor Member Posts: 7,265
    edited January 2015
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    Gordy wrote about being Italian and saving nails. I wrote about how futile it can be.

    I also saved every scrap of cut off new copper, steel pipe and PVC to use for short pieces. Never wasted though. I bought it, so, I might as well use it and sell it for new. Rather than put it in the scrap barrel and get scrap prices for it.

    When I was in the Carpenter's Union, I worked on this big balloon framed, brick veneer building. The Super. had a rule. No framing stock to the dump that was over 10" long. It had a use somewhere.

    I built a house. I had it rough framed. I finished the rough frame and the rest. When the framer left, there was a pile of lumber big enough to fill almost two 20 Yard dumpsters. When I was done picking though and cutting up scrap lumber, I blocked the entire house and there wasn't enough to fill my pick-up truck.

    Waste not, want not. If I had had him block and strap the house, he would have gone out and bought all new lumber. At my cost.
  • wrxz24
    wrxz24 Member Posts: 301
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    Update,
    1554 heating degree days/28 days....cold month
    Fuel used 360 gallons which is almost 13 gallons a day....yikes
    Boiler ran 476 hrs or about 17hrs a day for heat
    30 hrs for hot water/ hr a day avg
    4100 sqft which includes 28x32 garage floor that gets 90 degree water.
    15 hrs of dryer.




    This is by far the most fuel I used in a 28 day span but I never really factored in hdd's.
    So anyway, that is about 5.2 btu's per sqft per heating day
    360x 91,500 / 4100/1554

    For 74 days/ 3412 hdd's I burned 716 gallons or about 9.6 gallons a day.


  • Gordy
    Gordy Member Posts: 9,546
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    Thats not terrible. You have to factor out the dryer, hot water, and anything else lp powered. To get a real envelope performance for HDD per SF.

    I like to check it daily, and use the boilers DOE. That way I can correlate to envelope performance with actual btus delivered to the system.
  • wrxz24
    wrxz24 Member Posts: 301
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    So if the boiler used 12.8 gallons a day as the boiler ran for about 17hrs a day, the boiler modulated on avg to 69k/ hr for 17 hrs.
  • icesailor
    icesailor Member Posts: 7,265
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    Why would you heat a garage floor if you keep the doors and windows closed? Is someone living in the garage?

    I had a 20' X 24' two car garage, unheated. With a heated space above turned to 40, and one wall that was facing a conditioned space. No insulation in the walls. I never ever had anything freeze and when it was 20 degrees out, and I came home at 6:00PM with the roof covered with snow, and ice and snow falling on the floor from under the truck, it was all melted by 5:00 AM and had run out the door.
  • Gordy
    Gordy Member Posts: 9,546
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    You go through some serious dhw. Are you sure that's right?
  • wrxz24
    wrxz24 Member Posts: 301
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    icesailor said:

    Why would you heat a garage floor if you keep the doors and windows closed? Is someone living in the garage?

    I had a 20' X 24' two car garage, unheated. With a heated space above turned to 40, and one wall that was facing a conditioned space. No insulation in the walls. I never ever had anything freeze and when it was 20 degrees out, and I came home at 6:00PM with the roof covered with snow, and ice and snow falling on the floor from under the truck, it was all melted by 5:00 AM and had run out the door.

    I have pex in the garage that takes in up to 90 degrees of water. I added all my 3 radiant zones into one to limit the short cycling.
    So when the radiant runs, the garage gets a constant 90 degree water regardless of what the outdoor reset calls for that is above 90 degrees on the curve.
    When my upstairs bb zone calls, the other 2 radiant zones get 120 and 100 degree water. The upstairs rarely calls. However, since the upstairs circulator is wired directly to the boiler, whenever the radiant calls, the upstairs circ runs. No way around this on the tt 110. Have to get another relay for that one at some point. So basically when the radiant zones are on, so is the upstairs bb. Great for no short cycling, no more than 10-12 a day.... But fuel use is seeming to go up.
    Another problem is that I never insulated the wall between the house and garage, so if I leave the garage unheated, my mud room gets colder and that is where the tstat and floor sensor is.

  • wrxz24
    wrxz24 Member Posts: 301
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    Gordy said:

    You go through some serious dhw. Are you sure that's right?

    You mean 30hrs run time in 28 days? Much better than the 4 hrs that it was running a day before I fixed the piping and de scaled the hx coil.
  • Gordy
    Gordy Member Posts: 9,546
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    I don't think it's such a bad thing to warm the barrage......I mean the garage. Especially if you work out there.
  • wrxz24
    wrxz24 Member Posts: 301
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    Gordy said:

    I don't think it's such a bad thing to warm the barrage......I mean the garage. Especially if you work out there.

    It is nice most times and it stays about 60 out there most days. I figure when it gets up to temp, it doesn't need much heat from the boiler on most days...of course when it gets well below zero every night in what it seems like forever, then it does... As does the rest of the house.....
  • Gordy
    Gordy Member Posts: 9,546
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    Your calculations appear to be correct on avg. your averaging 56 HDD per day.

    Did you ever find out if the boiler modulation logging is input or output. I'm thinking the later.
  • wrxz24
    wrxz24 Member Posts: 301
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    I believe it is the output.
  • icesailor
    icesailor Member Posts: 7,265
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    If you don't mind heating unused spaces, you shouldn't mind paying for it.
  • wrxz24
    wrxz24 Member Posts: 301
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    icesailor said:

    If you don't mind heating unused spaces, you shouldn't mind paying for it.

    That's the problem, does having a little heat going to the garage floor when the other house zone calls help my overall situation keeping in mind that there is no insulation between the wall of the garage and house?

    Or do I just forget the garage, and master bedroom and bath for that matter, put them on its own zone, and keep it garage at 50 and bedroom at 65? Of course, from my experience before, the boiler has way more ignitions due to all the zones calling at different times and that makes the system less efficient.
  • icesailor
    icesailor Member Posts: 7,265
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    Why pay money to heat a garage space that you aren't using? The air in the uninsulated wall between the house and garage has a heat loss value. What makes insulation work is the trapped air in the insulation material. If the garage is a separate zone, turn it off. That's what zones are for.

    This obsession with burners running and cycling. My new car has Auto Stop/Start. Every time I stop, the engine stops. As soon as I take my foot off the brake, the engine immediately starts. As a fuel saving scheme. If I turn it off, I can watch the computerized MPG reading drop while the engine is idling. Because the engine has DCFI (Direct Cylinder Fuel Injection), rather than the older DPFI (Direct Port Fuel Injection) there is an issue of carbon blow back on to the intake valves. VW developed it in 1997 when the problems first started showing up.

    Where have we heard about exhaust gas regurgitation before?
  • wrxz24
    wrxz24 Member Posts: 301
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    You talking about my other thread on the combustion smell on windy days?
    Yes, I got sucked into the thought of longer run cycles vs the bang bang of my old smith ci boiler. That is why I went with a mod con thinking I could save some fuel particularly with a high mass radiant system. While I do save during the shoulder seasons, during this cold snap, maybe not so much and am a touch undersized as the floor gobbles up the btu's and boiler can not reach setpoint on my upstairs higher temp baseboard.
    Too bad I did not keep track of my old system, I could do some real number comparisons.....the only thing I can go by now is how much fuel vs hdd's and I am at 5.2 btu a sqft per hdd.
  • Gordy
    Gordy Member Posts: 9,546
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    Understand a btu used is a btu needed. None of that changes CI to mod/con. What changes is modulation ability, and a few more efficiency points. Your house still needs the same BTUs to off set losses.
  • icesailor
    icesailor Member Posts: 7,265
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    Then, there's all those additional BTU's available in the unintended, oversized systems. You never knew when you were using those extra BTU's. Until you went to the wall and put the perfectly sized (undersized) boiler in. Now that you need more NUTS, you don't have any way of getting them.

    Oil systems may be oversized for a heat load, not for a DHW load.

    But you could downsize the crap out of them, and upsize back up if you needed to.

    Undersized systems really do bite in really cold weather when they can't keep up. There is something to say about what all those old dead guys did on a regular basis. Piped nice warm houses. I never piped a cold house. It was embarrassing to have to tell someone that the system in their new house wasn't capable of handling the load when it was really windy and cold.
  • wrxz24
    wrxz24 Member Posts: 301
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    icesailor said:

    Then, there's all those additional BTU's available in the unintended, oversized systems. You never knew when you were using those extra BTU's. Until you went to the wall and put the perfectly sized (undersized) boiler in. Now that you need more NUTS, you don't have any way of getting them.

    Oil systems may be oversized for a heat load, not for a DHW load.

    But you could downsize the crap out of them, and upsize back up if you needed to.

    Undersized systems really do bite in really cold weather when they can't keep up. There is something to say about what all those old dead guys did on a regular basis. Piped nice warm houses. I never piped a cold house. It was embarrassing to have to tell someone that the system in their new house wasn't capable of handling the load when it was really windy and cold.

    I hear you loud and clear. I envy all of you guys who are constantly on the wall sharing your expertise and experience.

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