[chrismahon]

Because of the rainwater run-off into the fruit trees and also because it isn't as effective now due to chemical prohibition, we don't use weedkiller. Instead we have bought a large weed burner which is quite effective, although needs to be used often. Problem is it needs 2.5 bar pressure which it has initially, but after a short while the 13Kg bottle chills off (condensation on it) and the pressure drops. Then the flame isn't hot enough and it has to be left to warm up again. I've been using it with over half full bottles and putting the remainder aside for the cooker hob, which works better, but used it this cold morning and it was useless in seconds, even with a full bottle. At the moment it runs on Butane, as does the cooker hob, but the instructions say I could use Propane with the same regulator (we have different fittings to the UK).


I think Propane burns hotter? But is it less affected by the cold or chilling from evaporation- does anyone know? I don't want to stock more gas bottles unless I will get a practical benefit from that.

[macgro7]

Do you think storing bottles somewhere at home, or cellar would help? 

[Womble]

Storing butane bottles somewhere warm will help for a short time, but as you use it, it evaporates from liquid to gas, and that in itself will chill the liquid down (that's how a fridge works BTW).

But is it less affected by the cold or chilling from evaporation- does anyone know?

Yes, very much so. If you can use propane without having to change regs or fittings, that's going to be much better.

[chrismahon]

I'll be getting a Propane bottle Womble. The deposit on a bottle here is only 1€, so it's not a big risk.


Looked up the differences with Google, which annoyingly searched only in French- they are pretty significant. The boiling point of Butane is -2C and is suitable for interior use. Most cooker hobs here are Butane with a bottle kept under the sink. Propane with a boiling point of -42C must only be used outside and kept cool. Propane is more efficient in combustion, does give more heat and won't be affected by evaporation cooling. What's also annoying is there is no mention of this with the weed burner instructions! But I think in Summer I may have to switch back to Butane or only use the burner in the morning?


So another potential problem arises here. Our Butane cooker bottle is in the garage which could get below freezing and so wouldn't work. That hasn't happened yet, but perhaps it needs some insulation on occasions?

[arobwk]

Very interesting.  I've never looked into this, but will be looking to rationalise bottles for weeding and caravanning if I can and this thread will help me determine how many bottles I might need, to cover all eventualities.  Helpful - thanks.

[Womble]

So another potential problem arises here. Our Butane cooker bottle is in the garage which could get below freezing and so wouldn't work. That hasn't happened yet, but perhaps it needs some insulation on occasions?

The problem you've got there is that as the butane evaporates, it will cool down, and its vapour pressure will drop. Usually the bottle is then colder than the surroundings, so it absorbs warmth to keep the evaporation going. If you insulate it, that might actually be counterproductive, since it will stop that heat gain from the surroundings.


We do all of our cooking on propane cylinders which sit outside the kitchen window. These have never given us a problem so far, despite many cold Scottish winters.

[chrismahon]

I see your point about the insulation being counter productive Womble. Perhaps gently warming the cylinder may be necessary? Changing to Propane might need new jets for the rings, but perhaps that will never be necessary?


Anyway, I'll risk going into town next week and get a Propane cylinder. It will be a massive step forward if I can burn weeds in cold weather. When it's hot it's usually too dry as well and so a major fire risk using the burner here, so perhaps switching back to Butane will never be necessary either?

[Womble]

Chris, how about finding some sort of bucket that the butane cylinder can sit in? That way, worst case, you can heat some water to tepid on your woodburner (or whatever), and pour it around the butane. That should keep you going for long enough to cook a meal at least.

I did that for ages when camping. A friend's Dad passed away, and he found a stove and a load of camping gaz butane cylinders when he was clearing out his Dad's house. They were truly awful, even in summer, so I always sat the cylinder in some not-too-hot water, to ensure there was good pressure. I was sooooo pleased to use the last of them this summer though!

[chrismahon]

That's a good idea Womble. We haven't anything big enough at the moment but we're looking to buy something like a big pot for scalding chickens prior to plucking, so it may do both jobs?

[xillent]

turn the bottle upside down

[chrismahon]

Unfortunately turning the bottle upside down won't work for me. The heavy bottle is in a wheelbarrow with a 5 metre hose to the burner. Stop the barrow on the drive, burn 4 metres or so, leave the burner on the floor and move the barrow to it. Takes quite a while as the drive is 50 metres.


So to the supermarket and bought a cylinder of 9 kg of Propane (23€ + 1€ deposit). The difference to Butane with our gun has to be experienced to be believed. No loss of pressure at 6C, so I can burn all year. But the heat is incredible, so the job is done in half the time, perhaps less.


Downsides though. The noise, so very good ear defenders are essential. The flame is now colourless so care where it's pointing. So much heat that you can't get too near the drive edges or your feet or anything wanted undamaged.


I'm making a heat deflector so that I can burn to the edge of the driveway in a straight line, but Propane will be far too hot, so I will have to switch back to Butane sometimes.