LPG bottle frezzing problem

Discussion in 'Heating and Air-Conditioning' started by PaulJaq, Feb 25, 2013.

  1. PaulJaq

    PaulJaq Read Only Funster

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    Hi, We have a Suburban furnance on our 5th wheeler along with an atwood water heater, I have also plumbed in an LPG powered genny. The issue we have is when the heating has been running off and on for a few hours, the outside of the bottle frezzes and the gas pressure seems to drop which causes the furnace to stop or work on and off. If we run more than one as appliance this makes things worse. We swap to the other bottle and it works ok until that one frezzes. Any one any ideas how to overcome this? Some form of 12v powered jacket or band for the bottle? Or duct hot air to the bottle enclosure, a waste of heating that though! Or do I need to run a different regulator with higher pressure??? Do any of you have similar problems and how do you overcome them???

    Cheers Paul
     
  2. grasscutter

    grasscutter Funster Life Member

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    Are you definately using propane bottles. Butane freezes at a higher temperature than propane.
     
  3. reader

    reader Funster

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    As the outside temperature drops so does the available flowrate from the cylinder or tank, hence your problem. There is nothing to stop you lagging the tank to help things along.

    You can see this on static caravan sites during winter and many use this feature to determine how much propane is left in the cylinder:RollEyes:
     
  4. Chockswahay

    Chockswahay Funster

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    Although propane 'boils off' above -42c it still still gets to a rather low gas pressure around 0c and this might be your problem (?)

    When I used to fly hot air balloons we sometimes filled our flight tanks from the 47kg bottles. In winter the flow rate would sometimes become VERY slow so we used to pour boiling water on the outside of the bottles to increase the gas pressure (which we needed to push the liquid out).

    I doubt if this will always be possible for you but if your bottles are outside it might help on occasions?
     
  5. old-mo

    old-mo Funster Extra Special Life Member

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  6. Landy lover

    Landy lover Funster

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    Possibly worth having a look at the size of regulator you are using - if it is one for a small caravan/motorhome then it will not allow the volume of gas through - speak with the people at calor - you need one that would be used on a multi bottle installation for central heating to get a good flow - also bear in mind there is apparently a recommended service life for regulators - I think it is 5 years from memory others may know that better.
     
  7. scotjimland

    scotjimland Funster Life Member

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    Lagging won't help.. in fact it will exacerbate the problem by keeping the cold in..[HI] don't lag. [/HI]

    I suspect you are exceeding the bottle take-off rate What size bottles are you using ?

    The bigger the bottle the greater the take off rate is ..
     
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  8. old-mo

    old-mo Funster Extra Special Life Member

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    :Confused:........ How come Jim.... ?

    Surely if the tank is lagged it will stop it from getting cold in the first place....

    By way of stopping the cold air from reaching the Tank/Bottle...

    Or am I missing the point... ?
     
  9. scotjimland

    scotjimland Funster Life Member

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    the cold comes from the gas as it boils off .... ie .. inside the bottle.. lagging will insulate and keep it cold.

    you will have felt this when you use an aerosol can .. the nozzle freezes ..

    Each bottle size has a max take-off rate .. (i was looking for a chart, but not found it yet) .. if you exceed this or use it at max take-off for extended periods the pressure inside drops off and you see icing on the bottle...

    Heating the bottle will help.. but not lagging.
     
    Last edited: Feb 25, 2013
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  10. old-mo

    old-mo Funster Extra Special Life Member

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    I`m never to old to learn...

    Thanks Jim... :thumb:
     
  11. Terry

    Terry Funster

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    Agree with Jim on this :thumb: the OP is simply using gas too fast :BigGrin:
    It happens a lot with patio heaters as the bottles get half empty, they burn at a rate that they cannot keep gassing off at :Smile: even though they are under what is a hot heater :Wink:
    Heating the gas cupboard will help a little but using less appliance s at the same time would be more beneficial :thumb:
    Terry
     
  12. scotjimland

    scotjimland Funster Life Member

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    It's a common or popular misconception Mo.. have seen this (lagging) suggested on plenty other forums..

    still looking for a chart.. but as an example

    13 kg propane cylinder has a maximum recommended take of rate of 15kw

    a 47 KG cylinder is 34kw

    The solution is either increase bottle size or hook two same size bottles together and use simultaneously..

    Heating a locker with warm air would work.. but that has safety issues as you have created a fire and gas path back up the ducting into the hab area..

    Other option is to have a separate bottle for the genny
     
    Last edited: Feb 25, 2013
  13. Terry

    Terry Funster

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    I don't think you would be able to heat the locker enough to make much difference, after all it would be a viscous circle, burning gas to heat locker so that you can burn more gas :BigGrin:
    Terry
     
  14. olley

    olley Funster

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    I use a single 19kg bottle for heating and cooking, and so far no problems this winter with low pressure. I agree with jim, get two bottles both with a regulator and connect the outlets together with a tee piece, or buy a bigger bottle. Mine sit outside under the awning.

    Ian
     
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  15. scotjimland

    scotjimland Funster Life Member

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    When we were living in ours I did the same Ian, and no problem with bottle icing during the UK winter ..

    I had two 19kg bottles and filled at the local Autogas station using an illegal filling adaptor.. :Wink:
     
  16. PaulJaq

    PaulJaq Read Only Funster

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    Frezzing bottles

    Hi,

    Thanks for all the replies. I had googled the problem before posting on here and did find lagging is no good, you keep the cold in; the only way the bottle will defrost is because it is at a lower temp than the surrounding air even if that air is cold. Either way it doesn't defrost quick enough. I have one american white bottle about 10 - 12KG which we draw off first as it has a 80% safety valve for refilling and I would get less hassle from the petrol station (although I have had none yet) refilling that one with my adapter. The regulator is the original american one which feeds off one bottle first and then the second, or you can switch over a lever and do it manually. The second bottle I have is a 12KG red one, which we draw off and I fill that one up only very occasionally.
    Looking at the posts, yes heating the bottle in some way would work, but to duct the hot air from the normal duct would be a little difficult but not impossible. The bottom of the bottle cabinet is open to the elements - to allow any loose gas to escape, the bottom is completely open - I could blank that off a bit and still allow a smaller gas escape aperture. If not the heating wouldn't be that effective - at that end of the ducting the flow / heat is weak to say the least.
    I like the idea of drawing from both bottles at the same time through a T piece and a single regulator of sufficient flow rate. Would the bottles equalise in pressure if connected together - not quite sure what would happen here. So the availible draw off rate without frezzing or getting a drop in pressure would be doubled. I don't want to lug a 47KG around if I can help it. I did think about running the genny off of the second bottle only - or the one that is not being used for the other appliances, but I don't think it draws alot. I could test it next time out (in two weeks) and run the genny separate.
    The suburban furnace is at least a 20,000 BTU furnance, but could be up to 35,000 BTU, I'll check what model / rating it is within the next day or two. Also the Atwood water heater will have a BTU rating - for when that runs at the same time. Then the hob for boiling a kettle, then the genny which I know what Kg/h it draws hwich is about 1/2 KG/h.
    The only other thing it could be is there is an 'excess flow safety device' in the pipes / regulator somewhere. The instruction book says to connected and open and close the pair of bottles in an odd sequence to avoid the device kicking in. It says it will limit the delivery to about 20000 BTU if activated - so that would cause a problem. I'll check it out, but I'm not conviniced as the heating worked OK for a few hours when we swapped bottles and got the gas through. I tested it last night and after an hour or running - of and on the thermosat, ice was forming on the white bottle - which showed it was still half full - and that bottle wouldn't supply the heating when it had half inch of frost on it!!!:Doh::Eek!: The wife says why can't we get a normal caravan with a smaller normal heater. I might fit a carver 3 Kw gas heater as a back up - just run that when we have problems - direct - not ducted - it would be better than nothing.
    Cheers Paul

    PS would be interested in that max draw rate chart for different bottles - how does that convert to BTU from Kg/h??
     
  17. PaulJaq

    PaulJaq Read Only Funster

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    frezzing bottles

    Hi,

    Just googled 15KW and it came out 50000BTU, so as max draw off for a 13KG bottle, mines about 12KG, this shouldn't be a problem - but was???:shout::Eek!::cry:

    Cheers Paul
     
  18. Traveller_HA5_3DOM

    Traveller_HA5_3DOM Read Only Funster

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    There are various mixtures of Propane/Butane used on the continent so when you fill with Auto gas which most of us do you get a mixture that will run the engine of a vehicle that is burning the gas at a much slower rate than we do on a winters day with the heating and cooking going. It would seem if the country does not expect extreme low temps then they mix a larger quantity of Butane with it, I guess it must be cheaper.
    Scot Jim is spot on with his advice, Reduce consumption/DO NOT Insulate/consider linking two cylinders together to reduce the take off rate on each.
    Because the liquid boils inside the cylinder it has the effect just like a fridge does by using evaporation to reduce the fridge temperature.
     
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  19. Wildman

    Wildman Read Only Funster

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    not illegal Jim, just not recommended:thumb::thumb:
     
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  20. aba

    aba

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    unless the Calor police happen to see you.
     
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