# DIY heated gas locker ?



## peejay (May 10, 2005)

I have refillable gas bottles fitted to my Nuevo and we're off to Apline regions for 3 weeks in February. I think most of you are aware of the possible problems of using refilleables abroad in sub zero/Alpine temperatures because of the unfavourable butane/propane mix that euro lpg stations supply.

The blown air outlet pipe from the Truma runs under the settee and past the gas locker (steel lined) and I'm looking into the possibility of fitting a narrow branch from the pipe, drilling a hole through the sidewall and feeding a small amout of warm air to the locker. 

Can anyone see any safety problems with this and do you think it would work?
If not, any other ideas?

pete.


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## Paulway (May 9, 2005)

peejay

I would only consider doing that if I could feed the heated air in from the TOP of the conpartment. The danger of doing that at the bottom would be that in the event of an escape of gas, being heavier than air it would permeate to the base of the locker, where there should be outlet vents to outside air. But if there is a warm air duct entering it is possible that this could have gas enter it and then when the warm air blower turns on force it down the duct to exit into the van. The smell alone would be sufficient for me to not want to do it, let alone any possibility of danger.

PS
Perhaps if you could put a metal tube through the locker, sealed at each end from the locker, then blow the heated air through that the tube would become warm and act as a closed heat exchanger.


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## 92180 (May 1, 2005)

Instead of drilling a hole and drawing in warm air. Why not look at heat trace cable.

link http://www.elementshop.co.uk/products.php?cat=104.

It takes avery low current and transfers it along the cable. If you wrap it around the cylinders that might work. I don't think there is any chance of sparks . It is mostly used for water pipes so the insulation must be IP56

Hope this helps.

Failing that the cheap option hot water insulation bag.


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## Scotjimland (May 23, 2005)

Hi Pete 

I think Asgard's idea is excellent, trace heating cable and a nice thick piece of thermal insulation round the bottles should do the trick, provided you are on a hook up of course .. this is common practice throughout industry on oil and gas lines. 
It's easy to instal, requiring only a 230v supply, it self regulates along it's entire length no matter how long or short ..


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## spykal (May 9, 2005)

Hi Pete

Having thought about your idea, which I think is a great idea and should be OK , especially if you feed the warm air into the compartment at the top. The only suggestion I can come up with is to feed the hot air into the compatrment and back out again through a length of copper pipe maybe with some extra fins attached. In other words a sealed system...but I am not sure if this would be able to transfer enough heat. Maybe when making it up you could make it so that you could revert to an open system so that if it cannot cope with -20c as a closed system you would be able to open it directly into the cabinet.

Mike


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## gaspode (May 9, 2005)

I'm not too keen on the idea of feeding warm air into the gas locker, there's always the possibility of leaking gas finding its way back along the ducting and it would break the seal that the manuafcturer has carefully planned between gas locker and inhabited space.
Trace heaters would be good but will only work on hook-up.
I do however like the idea of a heat exchanger. If you could arrange a metal tube of about the same dia. as your ducting (sheet metal aircon ducting?) to run through the top of the locker you could seal it into the existing metal liner. Then divert one of your ducting runs to pass through the new duct and that should do exactly what you want. Insulating the locker door will also help keep the heat in.


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## RobinHood (May 19, 2005)

I don't think I would attempt to do anything in this space - safety and practicality issues.

If your trunking goes against the back of the gas locker, why not direct some heat on the reverse side of the locker with the appropriate slotted piece of trunking (they were fitted in my previous van to trickle feed heating to lockers - called a 'wall ventilator' in CAK catalogue). With any luck, and approapriately directed, this would heat a large proportion of the locker wall (steel or plastic?) from the outside. I used to duck-tape mine over when I didn't want the heating.

It shouldn't take much heat transfer to keep the locker above 4 degrees, and I can't see that you could fit much inside a gas locker that would have that level of surface transfer (unless you take the cylinders out :wink: ) .

If you take two cylinders from the UK and refill abroad, use the second UK one (with potentially higher propane content) as a reserve for the coldest times and only use until you can refill the other. Immediately substitute the refilled one back and see if it works, then you'll have the possibility of switching to the UK content if/when it is too cold for continental fill (e.g. overnight). This is, of course, much easier with a dual or auto-changeover valve.


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## Drew (May 30, 2005)

Hi Folks,

What about an insulated jacket for each cylinder? after all we use them in the loft to insulate cold water tanks. I am sure that one made of a suitable material would suffice without any risk whatsoever.

Regards

Drew


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## RobinHood (May 19, 2005)

The problem is that the act of drawing gas from cylinders cools them down. Insulating them can have the effect of keeping the temperature down rather than up!


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## peejay (May 10, 2005)

Thanks all, some very useful ideas and comments here.

The excellent heat trace cable idea is out i'm afraid as we won't always be able to hook up to mains. On a different track, last year Gaslow were looking into disposable wraps that work on a chemical reaction to heat the bottles but they seem to have come up with a blank on this.

I like the idea of a pipe running through the locker but, like spykal, have reservations whether it would transfer enough heat into the locker. It would probably be the best solution as the locker would remain sealed. Adding fins like a radiator to increase the dissapation of heat sounds good but where would I get such a set up ? I suppose it would have to be specially made.

Lagging the cylinder would maybe work for a while but with no heat at all in the locker i'm thinking this would only slow down the process and it would still eventually drop below freezing. edit, just seen Robinhoods reply about keeping the temp down rather than up so i think that ones out.

Using one 100% UK/propane filled cylinder as a back up is ok, but afaik when you refill a 2 cylinder set up there is no way to stop gas going into both cylinders but I suppose it would prolong the inevitable for a while.

I've looked through the truma parts catalogue and you can buy a cord operated shut off valve that fits inline with the ducting, this could be shut when the blown air isn't running stopping any gas running back down the pipe, but i'm still not conviced this is a satisfactory set up safety wise.

I'm taking the van down to ASSC at Willersey tommorrow for some warranty work so i'll let them have a look and see what they come up with, pretty sure they won't advocate any cutting holes in the locker walls but they may come up with something.

pete.


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## Drew (May 30, 2005)

Hi peejay,

For the past 25 years I have lived in the Chilterns, and during that time the tap in my unheated greenhouse has never frozen. The pipework to the tap is lagged as well as the tap itself.

In the building industry, pipes tanks and anything else that is prone to freezing are always lagged. Have a look in some car parks that have pipes running along the roof. This keeps out the cold air that causes things to freeze. 

By insulating your gas locker and lagging your cylinders you will for certain stop them from freezing. 

Lag one of your cylinders and put it outside on a cold night and see if it freezes. You have until February to experiment.

Regards

Drew


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## BrianR (May 1, 2005)

For the sake of other readers I will repeat hear the reply I posted to this query on the MMM Forum. With a well insulated gas locker you don't need much heat to keep butane "gassing". So why not put as many hot water bottles as you conveniently can in the gas locker. They should not need to be replenished too often. You could do this as and when necessary -after all, you might well never have a problem. 

Brian


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## spykal (May 9, 2005)

Hi

Brian ....I have used a hot water bottle :wink: in the Forest of Dean in the winter .... but not in the Alps. I got up one morning to find the gas not working...my mate said "why don't you boil a kettle and put a hot water bottle in there" Good idea I said and set off to do it..........After he had had a good laugh he boiled one for me (on propane) :lol: :lol:

Drew ....Whilst everything you say relating to lagging does work here in the UK, except in the very coldest winters which seem to be a thing of the past. But lagging gas cylinders that are in heavy use is of no use ...latent heat of vaporisation takes over and they get colder as the gas vaporises eventually freezing the gas (especially Butane).

But Peejay is off to colder climes where -20-25C is not uncommon, even in the daytime. ( I hope you don't get it that cold Peejay :lol: ) so he needs a method of warming the cylinders to above the temperature that the gas vaporises . He will also have the added problem that a lot of the european gas supplied is a mixture of Propane and Butane....so what happens below about 4C is that the propane gasses off leaving the Butane behind......you then go down to the refill station but find that you can only get a few litres in because it is 1/2 full of butane......eventually there is no room left for fresh Propane. Apparantly many folk using vans in the Alps find that they end up with a gas cylinder that is full of useless Butane Gas when all along they thought that they were buying Propane.

Mike


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## peejay (May 10, 2005)

Thanks Drew, I see what you're saying about lagging but the problem with butane is it stops working properly somewhere around +4c and i don't think lagging would raise the temperature that much without some form of backgtound heat. I'm talking of overnight temps between -5c to possibly -20c (we regularly had -15c last year)

Brian, similarly hot water bottles might work for a while but wouldn't they soon cool down with such extreme temps outside? I wouldn't fancy messing around refilling water bottles every few hours each night.

I do appreciate all of your ideas though and many thanks.

pete.


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## 89236 (May 17, 2005)

*Freezing Gas!*

Hi, I read with interest and not a little concern about spykal's "lot of the European gas supplied is a mixture of Propane and Butane". In this case, wouldn't we notice a lot of EU gas cars running out of usable fuel while crossing the Alps?

Stephen


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## DABurleigh (May 9, 2005)

No. LPG fuelled vehicles have a liquid gas take-off, where the boiling point of the liquid is irrelevant. For leisure applications you have a gas take-off, where butane fails to generate an adequate vapour pressure in low terperatures.

Dave


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## RobinHood (May 19, 2005)

*Re: Freezing Gas!*



stjaki said:


> Hi, I read with interest and not a little concern about spykal's "lot of the European gas supplied is a mixture of Propane and Butane". In this case, wouldn't we notice a lot of EU gas cars running out of usable fuel while crossing the Alps?
> 
> Stephen


LPG for engine use is taken off as liquid from the bottom of the tank. No temperature problem.

Gas for domestic use must be taken as vapour from the top of the tank (and butane doesn't vapourise below 4 degrees).

The two are not to be mixed.


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## spykal (May 9, 2005)

Hi Stephen

If the LPG cars used LPG in the same way as we do in our vans that would be true but the take off from an LPG powered vehicle tank is not gas, it is taken from the tank as a liquid. :roll:










Link to "How stuff Works" <<<<<<<<<<click here

Mike


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## 88782 (May 9, 2005)

Peejay


Here’s a suggestion, it would not be cheap and would involve a bit of work but I can see no reason why it would not work and not be safe, at least it’s something to kick around.

Have a jacket made in pvc coated polyester ( as used for boat covers) with inlet and outlet sleeves, the jacket to have a sealed bottom and an open top that’s a snug fit around the cylinder about 2/3rds up, sit the cylinder inside the jacket and clamp it around the cylinder with a metal band making it air tight, the inlet and outlet sleeves to be connected to a diverted hot air duct that again is sealed where it comes into the metal box.

The hot air would then be in direct contact with the cylinder and any leaking gas would still be able to drain through the drain vent.

KenS


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## Boff (May 10, 2005)

*Re: Freezing Gas!*



stjaki said:


> Hi, I read with interest and not a little concern about spykal's "lot of the European gas supplied is a mixture of Propane and Butane". In this case, wouldn't we notice a lot of EU gas cars running out of usable fuel while crossing the Alps?


Nope!

For domestic applications in a motorhome the gas is tapped from the gas phase in the gas tank (or bottle), so from the top. _Engines_ running on gas tap their gas out of the liquid phase in the gas tank, so from the bottom, and then evaporate it in a device called (what else :wink: ) "Evaporator", which can be compared to the carburettor in older car engines. So engines have no problem with butane even at temperatures far below freezing. And, as the LPG *fuel stations* are designed with the automotive application in mind, they do not take too much care about having butane contaminations in it.

*Lagging* the gas bottles, especially at temperatures far below freezing, is a very bad idea as due to evaporation in the bottles the temperature drops even further down than without lagging. When my bottles are in use at temperatures well above freezing, they get so cold that ice forms on them!

I would also strictly avoid any blow holes in the gas compartment. Should gas really leak out then the *heater* is really the last place you would want it to find it's way to. 8O

@ peejay: 
I only see one solution for your problem: Take only one of your refillable bottles with you. As soon as you are in France get a French bottle from one of the major suppliers together with an adaptor. Use the UK bottle only as reserve and swap the French bottle always as soon as it is empty. Just before you go home, return the French bottle again at the nearest branch of your supplier.

Best Regards,
Gerhard


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