Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

How low can UG propane tank reach before pressure dropping out?

sunlight33
sunlight33 Member Posts: 378
I have a 500-gal underground propane tank (on a lease) supplying fuel for my boiler. When it was at 21% I called my propane company and they told me I will be getting delivery soon because I am on their automatic delivery system with the remote motoring. Now it's 13% and the company reassured me again that I will not be running out of propane, but they wouldn't tell me the delivery date. I use about 1% (5 lb) of propane daily. I have been using this company for eight years and they had always been reliable, but they never wait the tank to be this empty before refueling. Perhaps the drivers are calling sick due to Covid but at what point should I start to worry? 5%?

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 22,916
    Propane delivery is much much more a matter of temperature than fill. What drives the propane out of the tank is the vapourization of the liquid -- and the pressure that exerts is entirely dependent on its temperature.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    sunlight33
  • jumper
    jumper Member Posts: 2,208

    Propane delivery is much much more a matter of temperature than fill. What drives the propane out of the tank is the vapourization of the liquid -- and the pressure that exerts is entirely dependent on its temperature.

    A good reason to bury propane tank? Also will ground reduce venting in summer?
  • Jamie Hall
    Jamie Hall Member Posts: 22,916
    Yup
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Zman
    Zman Member Posts: 7,542
    I would be more concerned about the accuracy of the gauge. With an underground tank, the temp will be stable and you should be able to go to 1% (unless the gauge is sticking).
    Both of my local propane companies have closed their local offices in the last few years. Dealing with their websites and call services has been a major PITA.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    sunlight33
  • Solid_Fuel_Man
    Solid_Fuel_Man Member Posts: 2,646
    I would say 5% is the real minimum I'd ever go. If you are using 1% daily, then I surmise you don't need to worry much about wetted surface for vaporization. That usage is low for a 500, which is helpful in that you can get away with going lower. 

    This is all assuming your gauge is accurate, which most generally are. 
    Serving Northern Maine HVAC & Controls. I burn wood, it smells good!
  • sunlight33
    sunlight33 Member Posts: 378
    Finally got the refill today. Even the driver himself was surprised at how low the tank has gotten to, well he said the reason for this lag was due to shortage of truck drivers.
  • hot_rod
    hot_rod Member Posts: 21,853
    Dave Yates just wrote a great article on this in PM Mag.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    sunlight33