LPG bottle frezzing problem (1 Viewer)

PaulJaq

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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
 

reader

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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:

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C

Chockswahay

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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?
 

Landy lover

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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.

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scotjimland

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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 ..
 

old-mo

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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 ..

: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... ?
 

scotjimland

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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... ?

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.

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old-mo

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I`m never to old to learn...

Thanks Jim... :thumb:
 

Terry

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Agree with Jim on this :thumb: the OP is simply using gas too fast ::bigsmile:
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 :winky:
Heating the gas cupboard will help a little but using less appliance s at the same time would be more beneficial :thumb:
Terry
 

scotjimland

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I`m never to old to learn...

Thanks Jim... :thumb:

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

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Terry

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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 ::bigsmile:
Terry
 
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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
 

scotjimland

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[HI]I use a single 19kg bottle for heating and cooking,[/HI] 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

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.. :winky:

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PaulJaq

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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::whatthe: 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??
 
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PaulJaq

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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::whatthe::cry:

Cheers Paul
 

Traveller_HA5_3DOM

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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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Wildman

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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 [HI]using an illegal filling adaptor[/HI].. :winky:
not illegal Jim, just not recommended:thumb::thumb:
 

cmcardle75

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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.

Actually, the car will burn at a much greater rate than the heater. After all, you'll probably use 100litres of LPG in a couple of hours in an RV, whilst 100 litres of LPG would give you many days or even weeks of heating. However, the reason it can draw off at such a large rate is that it doesn't rely on natural evaporation in the tank to get the gas. It couldn't, or they would freeze in minutes and never get enough flow rate to get out of the drive.

In an LPG fuelled vehicle, the fuel is actually transferred to the engine as liquid and a separate vaporiser component is used, connected to the engine coolant system to keep warm. Technically, a large heating installation could also use a vaporiser to increase flow rate, but I have no idea if they are available cheaply for such purposes. The system would be quite complicated, as it would still need a heat source to prevent freezing, which would presumably be obtained from the heater that it was supplying, either by preheating the liquid, or directly to the vaporiser.

Assuming extra insulation is not feasible, the cheaper solution is just to draw from two bottles at the same time, or use bigger bottles.

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scotjimland

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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::whatthe::cry:

Cheers Paul

the max draw off rate depends on the ambient .. the colder the ambient, the lower the max draw-off rate ..

not sure, but I think the max draw off rate quoted is at ambient of 20c
 

scotjimland

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PaulJaq

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frezzing bottles and draw off rate.

Hi again,

I have just spoken to calor - a nice lady whom was reading figures from her PC. She told me;
19KG - 1.37Kg/hr, 19Kw
13KG - 1.05Kg/hr, 15Kw This doesn't make sense as you would expect the 13kg to be less than 13Kw if prorata the 19Kg, also with larger bottles less affected you would expect the 13kg to be less than 13kw??:Doh:
She didn't have any info. on ambient temp. or at what temp the above figures relate to, could be 40 deg C:whatthe:

I also found the aws site you note and the chart which made more sense than the figures above. Also these figure indicate I would have a problem as the heater is about 8kw and the water heater is about 3kw, not sure what the hob would take, speaking to the genny people as an average I might use 1kw (maybe less). So 12kw total, should be within the 13KG calor figures, but not if the temp was 20C or even 15C as the temp last weekend was about 3C. With the aws figures I need 2 x 19KG to play it safe. Not sure what figures to believe. There must be a chart out there with ambient temp line along with draw figures for each bottle type!!
I will try one thing at a time. First pair both bottles together via a T piece into one side of the changeover valve, blanking off the other side. See if that gives enough draw off without problems. If still no good change the 12kg red bottle for a 19kg. If still no good change the white american bottle for a red 19kg along with the associated piping. If still no good insulate the bottle compartement and duct hot air into it whilst leaving a gas escape route at the bottom of the compartement. If still no good fit a 3kw carver heater and make do with that!:Eeek:
 

rainbow chasers

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The figures you have been given will be MAIMUM figures - use them as a guide only. They will be fairly accurate in OPTIMUM atmospherics.

As the temperature is dropping, this would be effected in it's boil rate - so you may be boiling at it's limit or near it.

Dualling the bottles will aid the gas flow, and lowering the boiling temp and thus raising the gas flow.
 
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PaulJaq

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dualing LPG bottles

Hi,
At the moment we have an american auto change over valve where both lpg bottles run into each side of the valve. There is a manual change over lever also. The valve contains the regulator from high pressure from the white bottle to low pressure for the appliances. It also contains an excess flow valve I think - unless that is in the pig tail to the white bottle. There is a red bottle on the other side which has an in line 18PSI regulator in the pipe from the bottle to the change over valve noted above. My question is, if I want to pair up these bottles, do I run them into and open T piece before they connect to one side of the change over valve. Then blank off the other side of the change over valve - do not use it with the manual lever pointing to the side with the T piece connected to it? How will the pressure of the two bottles equal out either if they don't have the same amount of LPG in them or if they are not the same size bottles (not that that should make a difference) or is this a stupid question:Doh:? How will the 18 psi regulator in the line to the red bottle affect the dualing set up, with the white bottle running into the T at high pressure - unless that has some form of first stage pressure reducer in the bottle valve, or should I take the red bottle 18psi regulator out and run open high pressure pipes to the T piece from the red bottle?
Cheers paul:thumb:

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Jul 29, 2007
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excellent .. cheers Terry :thumb:
that gives all the data, max draw off and kw

my first post with the kw data was way wrong.. that'll teach me to double check :Doh:

You may not be wrong Jim, as I think those charts are for "Handygas" which is a 60/40 mixture, and the draw of rate is low to stop the gas dropping below 0c, which according to them would mean only the propane would boil off leaving the butane in the cylinder.

The pdf is from Afrox, who say they are the leading supplier of Liquefied Petroleum Gas
(LPG) in sub-Saharan Africa. So a bit warmer than here. ::bigsmile:

Ian
 
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PaulJaq

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Frezzing bottle update

Hi,

I've just spoken to a very nice man at Calor again - techy bod. He said the pump gas they sell at the petrol pumps is the same as the bottle gas. In this country all autogas is to a standard which means it has less than 8% butane in it. He confirmed the draw off rate for a 12 / 13kG is 15kw, but that is at 20 degree C and at 0C the draw off rate would be less. For Butune he said at 0C the draw off pressure would be zero. Also for refillable bottles - the gas low type of course if you continually drew off the gas fast and in low temps (as we are doing every other weekend through the winter) after every fill at the pumps you increase the number of times the 8% butane would be left in the bottle. This would fill the bottle more so with Butane and the problem would reoccur more so. But it only takes a single use of all the gas in the bottle at higher than frezzing conditions and preferably not at high draw off to empty the bottle of butane. And you start again. Of course if you used Calor from red bottles - you only ever have 8% to deal with. He confirmed drawing from two cylinders would reduce the problem by half and heating the bottle compartement would help although Calor would never reccomend that due to safety issues - if the compartement got too hot. He did confirm that in europe - more southern countries the autogas and bottle gas is 60% propane / 40% butane and that would cause problems in cold climates. So use your foriegn gas up before you come back to a winter in blighty!

Still not sure how two different bottles will work together through an open T piece? Would the presure in both bottles equalise? The liquid gas can't pass from one to the other bottle without pumping.

Cheers Paul
 
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PaulJaq

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frezzing bottle mod works !!!

An update. I have done as noted in the last post; blanked off one side of the change over valve, fitted a T piece in the other side, turned the changeover lever to the T piece side of the valve, so the unit is just acting as a regulator now being fed by both bottles at the same time into the T piece. I have taken the 18PSI regulator out of the red bottle side so the pressure from both bottles is equal. The gas draws from both bottles at the same time and although they still get a little cold the frost on them is minimal / not there, as the draw down rate is doubled without frezzing. I just need to keep an eye on the gas level in both bottles, but we top them up at the petrol station between trips anyway. We have just had a weekend away with very cold weather and no problems.:roflmto::thumb:::bigsmile:
So if you have a problem T the bottle together to allow a draw down rate of double before the bottles frezze.

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