Winter gas setup

[ROBERT_374321706]

Hello, I want to extend my usage into colder weather by fitting a propane cylinder to my 1991 ABI. At present I have a big butane which I couldn't use up if I tried in one season. I normally tour solo, sad but true!

Sooo, what I want to do is fit two smaller gas cylinders, one of each obviously. I know that I need a different regulator for propane, but can I get a simple "y" **** to switch between them? Anything else I should do? I am told that the cooker, heater or water heater burners don't need anything done.

Or maybe I should ask, do I need to bother with propane? At what temp does it become neccessary. I am in Scotland by the way!

BTW, -after not been in a caravan for over 35 years, (when I was a nipper at North Berwick) I bought a van this year. Wonderful! Real holidays, and nice people.

Shame about the strange breed in some sites tho', the Costas have a lot to answer for! No consideration, and kids run riot 'til 2am, while LCD tv blares from tinted windows. Ostriches. Oh no, I've just turned into my Dad!

 

[rob_jax]

Robert,

As you run a 1991 caravan, two smaller bottles - with their correct (bottle top) regulators and a change over valve - is a good idea.

The change over valve needs to be the correct type, any old valve won't do. So check out the Gaslow web-site for their low-pressure manual changeover valve - these won't allow you to direct the gas incorrectly and are intrinsically safe in use.

Likewise, if the flexible rubber tubing is of the drinking straw type (thin-wall) - then change that to the thick-wall type - this has a life of 3 to 5 years (visual inspection necessary) from date of manufacture (stamped on the tubing)

Many people have the misguided impression that Butane freezes in cold weather - it doesn't freeze until a temperature of -138

 

[ProfJohnL]

Hello Robert,

I agree with Rob-jax, but as I no longer have access to the latest gas regulations documents, I am not sure if there is any stipulation about having two different types of gas connected to the same system.

However from a technical point of view. It is vitally important that the change over valve used must not allow both bottles to feed at the same time. So you must find a change over valve that definitely breaks before makes flow paths.

 

[Lutz]

John, you emphasise that one must not allow the content of the butane and propane bottles to mix. Out of interest, is this only to prevent contamination or is there another technical reason behind this advice? I ask because the gas that you buy here on the Continent is a mix of the two (that's why we don't have to swap over between summer and winter).

 

[Robert_374242026]

From another Robert, this has been one of the most intresting topics to me regarding the answers to the other Robert ,i had started to lose interest on Forum with the same old discussions and the way it goes off course ,well done.

 

[ProfJohnL]

Hello Lutz,

There is no problem with mixing Butane and Propane gas in the same bottle as supplied in many parts of the continent. They would emerge from the cylinder at a common pressure and be dealt with as a single gas supply.

The problem arises with having two fuel systems at different pressures using a common line. The design must prevent the accidental connection of both fuels at the same time such that one system might interfere with the other. In Robert's case his 1991 caravan will be set up for the UK's two-pressure system where Butane is supplied at 28mBar and Propane at 37mBar.

With the majority of modern regulators, the 28mBar model would probably withstand the excess pressure created by the 37mBar propane unit.

I recall that Truma used to sell a dual regulator set that exploited a small pressure differential between two similar regulators to automatically change over between a main cylinder and a reserve. The difference here is that they were both supplying the same type of fuel. Once the main cylinder was empty, (denoted by a bottle pressure gauge,) the bottle could be removed and changed whilst the reserve continued to supply. The regulators did not rely on the diaphragm locking off, but they had a separate and spring-loaded shut-off valve built into the bottle connector.

BUT, not all regulators are suitable for this type of duty. Some diaphragms in regulators were moulded to a specific shape and are not designed to withstand excess pressures on low-pressure side. The problem here is you don't know which type you have.

From my increasing dim and distant past, I do recall there was some part of the regulations that covered the legality of connecting two fuels at different pressures on a common line. I am pretty certain that it is illegal, so it is sensible to if not a legal requirement to ensure cross over cannot occur.

Options:

Separation by changing pig-tales/regulators,

Break before make change over valves,

and possibly non-return valves may satisfy the regs.

 

[Bob_374302597]

Hello Lutz,

There is no problem with mixing Butane and Propane gas in the same bottle as supplied in many parts of the continent. They would emerge from the cylinder at a common pressure and be dealt with as a single gas supply.

The problem arises with having two fuel systems at different pressures using a common line. The design must prevent the accidental connection of both fuels at the same time such that one system might interfere with the other. In Robert's case his 1991 caravan will be set up for the UK's two-pressure system where Butane is supplied at 28mBar and Propane at 37mBar.

With the majority of modern regulators, the 28mBar model would probably withstand the excess pressure created by the 37mBar propane unit.

I recall that Truma used to sell a dual regulator set that exploited a small pressure differential between two similar regulators to automatically change over between a main cylinder and a reserve. The difference here is that they were both supplying the same type of fuel. Once the main cylinder was empty, (denoted by a bottle pressure gauge,) the bottle could be removed and changed whilst the reserve continued to supply. The regulators did not rely on the diaphragm locking off, but they had a separate and spring-loaded shut-off valve built into the bottle connector.

BUT, not all regulators are suitable for this type of duty. Some diaphragms in regulators were moulded to a specific shape and are not designed to withstand excess pressures on low-pressure side. The problem here is you don't know which type you have.

From my increasing dim and distant past, I do recall there was some part of the regulations that covered the legality of connecting two fuels at different pressures on a common line. I am pretty certain that it is illegal, so it is sensible to if not a legal requirement to ensure cross over cannot occur.

Options:

Separation by changing pig-tales/regulators,

Break before make change over valves,

and possibly non-return valves may satisfy the regs.

Well, thanks for the excellent replies! Nice to know there are so many knowledgeable and helpful people on this forum.