Habitation Gas Regulators

[Terrytraveller]

I have a 2004 registered camper (pre bulkhead regulator 30mbar). I have checked all my gas appliances, and the data plates indicate that I can use 28/37mbar and 30mbar pressures using the either butane (28mbar) or propane (37mbar) or both (30mbar). Looking at various web sites, I find that campers/caravans up to 10 years old will most likely be fitted with appliances which will operate on the 30mbar standard. Calor gas and other various sites, probably using information from the calor gas leaflet, state that you CANNOT convert to 30mbar. What gets up my nose is that they do not give a reason for this statement, just a don't do it! If there is a knowledgeable gas engineer engineer out there, or even a well informed DIY who has converted a 'van' to 30mbar, and can give an explanation it will be well appreciated. It seems there has been a high failure rate of the 30mbar regulators. An article in the Caravan Club magazine, August 2006, page 12 'Regulator Irregularities' seems to suggest its the way the units are mounted, and suggests you take a spare with you when in of europe! Regards to all Terry

[johnsandywhite]

:-( This may not be what you want to read/hear. But I have been using gas bottles in all shapes and sizes since having been a Plumber back in the 70's to using them in Tents, Caravans, Campers, Motorhomes and RV 's. I have used large bottles, small bottles, camping gaz bottles from here and in Spain. I have plugged various bottles into a 'T' connection to our on-board ACME fitting tank. Propane, Butane or a mix of various degrees from European fill-up points. Not once did I consider what the mbar should or shouldn't be. As long as you use the CORRECT regulator for the type of bottle you are using. There should not be a problem. IMH&VHO. Happy Motorhoming. ;-)

[Terrytraveller]

Hi Johnsandywhite, Thanks for you reply, I agree about the CORRECT regulator, I use a mixture of bottles at the moment when on the continent, each with its own regulator. I didn'texplain fully why the questions have arisen. I am changing to twin gaslow LPG 6kg refillables, and I am at the stage of trying to select a regulator either 37mb or 30mb, bearing in mind that european LPG is a mixture of both gasses, I don't want to overflame (if thats the word), the appliances I have installed in the camper due to the possibilty of 30/70 propane/butane mix of Autogas on the continient, if the LPG remained at 100% propane, as its suppose to be in UK, then I would have no query, it will be good at 37mb. It seems to me that the 30mb regulator would be a good compromise, but whats the reason for the calor gas "DON'T DO IT" statement. Regards Terry

[Brian Kirby]

Terry

Since it will be the appliances that are affected and not the gas bottle, why not ask the appliance manufacturers whether the appliances are safe to use, or can be modified for use, on propane or butane at 30mb? 

Most appliances should have a type/model reference and probably a serial number so the manufacturers ought to be able to say. 

E-mail them, so you heve a record of their answers and who gave them, it's surprising how much more careful people become before they write!

[johnsandywhite]

:-D Hi Terry. As I mentioned. I have used ALL the variations you can think of in the way of Gas mixes and bottles etc. ALL the appliances worked in a similar way. Yes there are differences in Butane (freezes easier but burns hotter) and Propane (burns cooler but works in a cooler climate). But to all intents and purposes the Cooker, Heater/Furnace etc will all perform as they were designed. Our in-built tank works the appliances equally well on 100% Propane and a mixture as can be bought in Europe where more Butane is added to the Propane in their LPG mixes. I also had an LPG conversion on our old 1988 Coachmen so you could tell when we were in Europe. :-( Calor Gas is covering itself by 'DON'T Do IT' statement. Tank pressure can be anything from 20psi to 250psi depending on the amount of gas and the temperature. The regulator regulates this down to 11" to 12" water column. All the appliances have their own regulators besides the tank regulator. ;-)

[Terrytraveller]

Hi Johnsandywhite, Brian, Had a look around the web (yet again), and there dosen't seem to be a big mystery about gas pressures, have a look at http://www.calor.co.uk/about-calor/press-room/step-by-step-lpg-conversion.htm although this is nat gas to lpg, calor mention only propane lpg. I was a bit taken aback by the suggestion that each appliance has its own regulator (Hi Johnsandywhite), it dosen't appear so, it seems only the injectors need to be examined, which appear to have a wide tolerance, encompassing 28 to 37 mb pressures. I can see that there may be an aeration adjustment to make sure the CO2 settings correct, a job for for an experienced gasman with a gas analyser, I think. I would still like to hear from anyone who has converted from 37mb to 30mb, if I don't hear - then perhaps we should assume they can't respond... 8-) I will write to Autocruise Brian, as they should have all the info regarding the regulator changeover, they must have changed their production over a few months after manufacturing my camper. Regards Terry

[Basil]

Hi Terry The reason that Butane and propane have different pressure settings is because the two gases have differing CV's (Calorific Values). The gas used by an appiance gives a pre determined heat output that is decided by the heat input and the efficiency of the appliance. For example a heater that is 75% efficient that is required to give a 3kW per hour output that would need a 4kW input, this is purely an example and many gas appliances will be more efficient than this. The CV of a gas is measured in a given amount of heat (in MJoules) per cubic metre. Now the amount of gas passing through a fixed oriface (injector) at a given pressure will give a set flow rate in cubic metres per hour and that will therefore determine the amount of heat flowing through the injector per hour (MJ/cubicM). Using the same gas, if you increase the size of the injector the flow rate will increase, thus giving a higher input and hence output. Likewise if you leave the injector the same size but increase the pressure there will be a greater flow rate through the injector and again an increase in input. Now if you use the same size injector but pass a gas with a higher CV at the same pressure as a lower CV gas, the flow rate will remain the same (not exactly but for this discusion assume it is) but the heat content of the gas (CV) will cause an increase in heat input. Therefore from this we can conclude that Butane (having a higher CV than Propane) at 28mb will give the same heat input, also output from previous discussion, as Propane (having a lower CV than Butane) at 37mbar. For appliances that are designed for the 30mbar regulator, the appliance designers have determined an injector size at 30mbar that will give the correct input, within a given tolerance, for either gas. The effect of increasing the input above the design tolerance could be to overload the outlet flue, create poor combustion through lack of air, cause overheating of the appliance and other possible problems associated such as flame lift giving nusiance outage due to flame failure devices. Hope that helps you to understand that it is not just Calor trying to cover themselves!!

[johnsandywhite]

:-S Or to put it simply. It will burn hotter with Butane and cooler on Propane using the same regulator for both. When the temp drops down. The Butane may stop gassing and therefore not burn but the Propane will continue to gasify and burn.

[Derek Uzzell]

Terry: As I understand it, received wisdom is not that you CANNOT fit a 30mbar gas regulator to a leisure-vehicle that was originally constructed with a 28mbar(butane)/37mbar(propane) system, but that you SHOULD NOT. The reason for such advice is plain - it's simply because altering the regulator pressure introduces an unquantifiable unknown into the safety equation. If gas specialists like Calor said "It's OK to swap from 28/37mbar to 30mbar regulator in the following cases, then people would just do it and ignore the 'in the following cases'". So it's a whole lot safer (for everybody) for the idea to be vetoed. Of course that doesn't mean it can't be done... When I owned a 1997-built Herald I looked into changing to a 30bar regulator. The Herald had 4 gas appliances - Truma Combi heater, gas oven, gas hob/grill, fridge. The literature for the heater and oven showed they were both '30mbar compliant', while the hob/grill was notionally 28/37mbar but, when I investigated further the butane/propane operational pressure ranges were quite wide and encompassed 30mbar. The Electrolux data for the fridge indicated there was a 28/37mbar model (mine) and a 30mbar variant. I contacted the company to ask what the technical differences were and whether there might be insoluble problems using a 28/37mbar fridge at 30mbar gas pressure but they referred me to my local UK caravan dealership (Hah!) At the end of the day I chose to keep the standard on-bottle 37mbar propane regulator, not because I thought swapping to a 30mbar regulator would be unsafe, but because I didn't think it would be worthwhile. (You might want to note that I've got a refillable LPG bottle and I had no apparent problems burning Continental butane/propane Autogas mix via a 37mbar regulator.) In fact, across the years, lots of motorhomes will have been 'accidentally' converted from 28/37mbar to 30mbar. This will have occurred when owners decided to fit Truma's Triomatic automatic twin-bottle switch-over system that is based round a 30mbar regulator. The Triomatic Installation Instructions begin "Attention: The system regulator of the Triomatic (30mbar) must correspond to all the installed appliances!", but it's doubtful if people took this to heart. The UK got on the 30mbar regulator band-wagon only recently and, before that, Calor (et al) weren't making dire pronouncements about potential risks in switching 28/37mbar systems to 30mbar. In April 1999 MMM published a "Long-Term Project DIY" article describing installation of Triomatic on an elderly Autoquest and absolutely no mention was made of matching appliances to regulator pressure. Presumably, after installation, the system worked satisfactorily and (as I don't recall any follow-up obituaries) I assume it continued to do so. As your Autocruise will have been built to modern standards I don't believe swapping from a 28/37mbar regulator to a 30mbar will make a scrap of difference safety-wise. Conversely, if you use Continental Autogas at 37mbar I don't envisage any problems either. Logically, it might be sensible to opt for a 37mbar regulator (which is the uncontroversial choice) and move to a 30mbar version if the 37mbar one shows any evidence of unsuitability. What do Gaslow advise? The August 2006 CC Magazine piece about regulator failures is the best-balanced article on the subject I've read so far. The Truma bulkhead-mounted 30mbar regulator in my Hobby suddenly stopped working soon after its installation. Although regulator positioning, gas-hose length, etc. may be factors in the on-going spate of regulator failures, in my case the regulator was located high up in the gas-locker with its inlet facing downwards and with a (deliberately) long gas-hose to try to catch any 'oily residues'. When the regulator ceased working its inlet and the gas-hose were perfectly clean. I now carry TWO back-up regulators, but the only effective preventive measure I can envisage is to filter the gas pre-regulator. (Such filters are now available in France but not, I think, in the UK.) Some models of regulator appear to be less prone to contamination, but (to me) the implication of this is that the 'muck' is passing through the regulator where it will eventually reach the gas appliances. In many ways it's preferable to have a dead regulator (probably replaceable under warranty) than a dead heater (that definitely won't be).

[Basil]

Hi JSW Absolutely correct! The question is whether or not the increase or decrease in input will have any detrimental effect on the appliance. In the case of using Propane at a lower pressure than design it would probably not harm the appliance but will not give the required output and therefore may make the appliance less efficient e.g. not giving sufficient heat output th the habitation area or a fridge not cooling sufficiently in hotter weather. With Butane, in total, there is the risk of burning out heat exchangers or surrounding equipment from overheating or damage to decorative parts that are now to close to a much hotter surface. With the Propane/Butane mix such as is available for Autogas on the continent I do not believe that there would be much of a safety risk in fact I believe that under performance would be the bigger concern. The forgoing reasons is why I have chosen to use a standard Gaslow manual changeover regulator for Propane with my Gaslow installation which has, IMO, the same advantages as the 30mbar regulator but with the correct 37mbar pressure requirement for Propane, this has been in use for some while now with no detrimental effects, I am unclear as to why anyone would wish to use the 30mbar offering on an older system as I see no advantage.

[Basil]

Terry If your appliance data badges state that they may use the 30mbar standard, as you say in your first post, then they can and there is no reason why you should not change to that system if that is what you desire.

[Terrytraveller]

A big thanks to Derek and Basil, not forgetting all others who have put a great deal of time and thought, in giving a detailed explanation regarding my query. I must admit I was concerned about the autogas mix ratio situation found in the continental supplies, and the effect it would have on the appliances. Reading your explanations has certainly put my mind at rest, again very many thanks. Incidently - Gaslow have run out of 6Kg cylinders yet again, they inform me that they are expecting a shipment from Portugal next week. I went to Brownhills Swindon to get advice about installing the filler kit, asking if they thought it was safe to cut a 70mm hole in the side of the van which would protrude into the inside locker, and run the filler pipe on the floor of the van inside the locker under the sofa, to the gas locker. Although they said yes, I noticed that the gas locker is completely sealed from the inside of the van, even to the extent of spot welding the bracket inside the gas locker which secures the 8mm copper feed pipe passing underneath the van, as fitting screws to retain the bracket would have compromised the gas tight locker seal inside the van. There other suggestion was to drill a 70mm hole in the locker door to mount the filler. I was not keen on that idea, as every time you open the locker door the pipe would flex and rub on something or other. In the end I made a removable bracket to retain the LPG filler and cap, mounted to the roof of the locker inside the locker door, attaching the bracket to a plate with four studs. The filler bracket is secured to the top of the locker with four butterfly nuts screwed onto the four studs, so the bracket complete with filler assembly and steel flexible pipe can be removed for cylinder installation and servicing. Best regards to all - Terry

[Basil]

Hi Terry If you are interested East Coast Leisure have both sizes of cylinder in stock, or they did as of Friday, they can be found at WWW.east-coast-leisure.co.uk They keep most of the Gaslow equipment at a price cheaper than most plus they give you 5% discount if you are a Caravan Club member. I managed to squeeze an 11kg Gaslow refillable plus a 6kg into our gas compartment, gives nearly a third more capacity than the standard setup, the weight penalty of the setup on the weighbridge is not a problem

[Terrytraveller]

Hi Basil, Thanks for the info, I had a look at WWW.east-coast-leisure.co.uk , their prices seem to be Gaslow RRP, but as I only live 2 miles from Brownhills Swindon, it's more convenient to pick them up from there, and no delivery charge too. I was suprised that there is a possibilty on the first fill that the 80% cut off won't work, have to watch that I don't exceed the 24 ltr mark for both cylinders. There should be negative pressure in the new cylinders, but the ones at Brownhills, had their taps on so they will need venting off before fitting the regulator, according to the instructions. I wish I had room for the 11 kg cylinder, but is going to be a tight squeeze to get in two 6 kg's. - Did your cut off work okay on first time fill? Thanks again Regards Terry

[Basil]

Hi Terry, Did not know your location so put up the info anyway, the in store prices are cheaper than the on line ones by the way, and there is the 5% as well. My 11kg cost £79.50, manual changeover, reg and tails £39.45 and filler £46.25. I thought that for £165 that wasnt a bad deal seeing as I was quoted nearly £400 fitted at the Peterboro show! I thought I was'nt able to get the larger bottle in, in fact I was told I couldnt by one of the suppliers at Peterboro show last year, it also looked like the 11kg would take up too much space to fit more than just the 11kg but ECL said I could try it and have a refund or exchange if it did not fit so I had nothing to lose trying it. When I looked I found that the door opening was smaller than the actual locker height by about 4inches and by removing the rubber seal from the inside of the frame, that gave another 1inch, it was about one eighth of an inch short of the cylinder height so carefully bending of the lip of the alloy frame where the rubber attaches to allowed the cylinder to just about slip in. After straightning the frame alloy and refitting the rubber to it there is no imperfection at all. I then had room in front of the 11kg for a 6kg which currently I am using a standard Calor Propane as I have several full ones that I will use before deciding whether to keep like that or add a second 6kg Gaslow. Regarding the first fill, yes a bit heart stopping! Mine operated perfectly first time but it was a bit, gulp, as it came up to 21litres wondering if it would or not shut at the intended 22.5, mine actually stopped just around 22litres, not sure why.