DIY heat storage

sardo_67 Posted By sardo_67, Nov 13, 2017 at 2:16 PM

  1. nhtreehouse

    nhtreehouse
    New Member 2.
    NULL
    

    Feb 11, 2017
    50
    9
    Loc:
    New Hampshire
    Yes. My 1000 gallon tank is 5/16" thick on the cylinder and 1/4" thick on the heads. It should weigh in at around 1800 lbs. In comparison, oil tanks are measured in gauge, not inches. I'm sure someone here knows how thick they are, but a guess would be 14 gauge. That's a bit over 1/16". Pressure is no problem with propane tanks as they are originally built for something like 250 PSI. Another important fact is that with a propane tank you can run the system pressurized without a heat exchanger, as others have commented on here.

    Other members have cut propane tanks down and used multiple tanks for tight locations. It works.

    I put together a simple spreadsheet to calculate tank volume. Using that tool, I come up with about 277 gallons per tank if you start with a 500 gallon tank which is typically 37" in diameter, and cut it down to 6' length overall. That assumes the heads/ends are hemispheres which is not always the case. Your mileage may vary here. Happy to share the spreadsheet - just PM me.
     
  2. maple1

    maple1
    Minister of Fire 2.
    NULL
    

    Sep 15, 2011
    8,486
    1,601
    Loc:
    Nova Scotia
    so with the propane tanks i don't have to worry about rust since they are much thicker?

    Well, partly. Most of the rust worry goes away by having things pressurized - no fresh air in the water to make rust. And LP tanks allow for pressurized. But if you are cutting & welding them, you want to be very careful how you do it. They are designed the way they are for the pressure, so changing that by reconfiguring the tank itself can change their pressure handling capabilities. That plus making sure the new welds themsleves can stand the pressure without leaking. I had bungs welded on mine by a pro shop and even they had to touch them up in spots due to pinholes in the welds. Partly my fault for accidentally getting cast fittings.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  3. peakbagger

    peakbagger
    Minister of Fire 2.
    NULL
    

    Jul 11, 2008
    3,806
    975
    Loc:
    Northern NH
    Your question raises a red flag. There are two types of storage, pressurized and unpressurized. With pressurized you heat up a tank of water through a heat exchanger and then you need a heat exchanger (maybe the same one) to get the heat back into the radiators. Its decidedly more complicated.The reason you need the heat exchangers is that most wood, gas and oil heaters are cast iron with iron pipes. If you just circulated the water in the boiler to the tank without a heat exchanger, oxygen would get into the boiler water and rot the boiler out quickly. A pressurized system uses a closed tank that can be operated at the boiler pressure with no need to vent oxygen into the system. Its simpler to hook up but the trade off is you ned a tank capable of being pressurized with the right connections. A propane tank when built did have the pressure rating but not the right connections. This means that you need to have the right connections welded onto the tank. Unless the welder and his company has a special certification, the tank loses its official pressure rating. The typical reason the tank is available to begin with is its age or condition means that the original owner did not want to re-certify it or it was not able to be re-certified.

    Some states like Mass technically require that any pressurized tank installed have a valid certification, many do not. The risk for a tank full of water failing is very low compared to one full of propane or air. Water cant be compressed so when the tank fails it most likely leaks all over the floor. When a tank full of propane or air fails it can explode and throw shrapnel around. Therefore many folks who heat with wood and use a modified propane tank accept the risk from a leak and go pressurized.

    At this point I would suggest you do a lot of research before buying anything. Plenty of folks are willing to help you decide but ultimately if you are DIYing it you need to understand the basics or you will get into trouble.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  4. sardo_67

    sardo_67
    New Member 2.
    NULL
    

    Sep 19, 2017
    63
    1
    Loc:
    mid CT
    yes i am doing a pressurized system, much simpler, easier and cheaper than building the heat exchanger and what not.

    i have been a production welder for a few years before my current job and will be pressure testing these before i install them, it's just hot water, not working on 4,000PSI natural gas transfer lines here, ill put about 50psi into the tank then check all the welds with some soapy water for bubbles.

    my issue is i have an MB55 which is 140,000BTU for my house and garage that only add up to about 1500sq feet of living space so i really need storage or the boiler will be choked down very low and clog up pretty quick. then add in the horrible efficiency which won't help either.

    i've been reading a lot on here over the past year+ and learned a lot, just things didn't work out last year as i took on too many things at once, now i am in a much better situation both time and finance wise to finally finish this project.
     
  5. sardo_67

    sardo_67
    New Member 2.
    NULL
    

    Sep 19, 2017
    63
    1
    Loc:
    mid CT
    ok one thing i forgot to ask about is how to insulate these?

    build a box around them?

    spray foam?

    blankets of some kind?
     
  6. maple1

    maple1
    Minister of Fire 2.
    NULL
    

    Sep 15, 2011
    8,486
    1,601
    Loc:
    Nova Scotia
    I did a simple box.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  7. sardo_67

    sardo_67
    New Member 2.
    NULL
    

    Sep 19, 2017
    63
    1
    Loc:
    mid CT
    going to start cutting and welding on my tanks, however i am not 100% sure how i am going to route the water flow and plumbing.

    simply put should i go with option 1 or two?
    i know there is a lot more in the system however i just made it extra simplified for conversation sake
     

    Attached Files:

  8. salecker

    salecker
    Minister of Fire 2.
    NULL
    

    Aug 22, 2010
    717
    186
    Loc:
    Northern Canada
    Neither.
    My system was designed by the guy i bought the boiler from,he is supposed to be one of the best in the Territory of 40000 people.
    My sytem feeds into the top of tank 1 with 11/2 pipe with a reducing tee to the top of tank 2 with 11/4.
    Then the return comes out of the bottom of tank 1 with 11/4 and upsizing to 11/2 at the tee from tank 2 which is 11/2.This a reverse of the input plumbing. My tanks balance equal both charging and discharging.
     
    Stop hovering to collapse... Click to collapse... Hover to expand... Click to expand...
  9. sardo_67

    sardo_67
    New Member 2.
    NULL
    

    Sep 19, 2017
    63
    1
    Loc:
    mid CT
    ok so how are they organized though, one feeds into the other or both equal?

    i am going to use the HS tarm print here as my basic guide but i am not 100% sure about all of it. like as you mentioned what size to use for the pipes and fittings or where to place them on the tanks.

    (see wood plumbing example #4)
     

    Attached Files:

Share This Page