Rath

Burner questions from a newbie

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Hello everyone!

I like many people, am just dipping my toes into the waters of blacksmithing. I have spent the last few weeks on forums and youtube trying to figure out what kind of forge I wanted to build. I decided on propane, which lead me further down the rabbit hole. That rabbit hole lead me to burners and trying to figure out if Venturi or Forced Air was the right choice for me. I know that they both have their pros and cons but there are a few things that I haven't been able to find too much information on. So I am hoping that some more experienced smiths may be able to help me out here.

My first question is on fuel efficiency. Basically I am running on a fairly tight budget and I want to make an informed decision. I have seen people claiming that forced air burners are many times more efficient than Venturi burners. I have seen people that claim they are about the same. At the same time there are people that say it depends more on how well your forge is insulated. I have zero clue where the truth falls in this spectrum. I also realize that it is possible that the answer is that there is no right or wrong answer.

My second question is how weather affects the burners, and which one would perform better for my circumstances. I live in Missouri and our weather is very bipolar. It can either be really hot or more mild and damp. One thing that is almost always a constant is the humidity. I walked outside this morning and we were at 100% humidity. My forge setup will be outside in our backyard area so the humidity and moisture are just always going to be a factor.

Any help that you can give me would be much appreciated.

Rath

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Funny thing; no matter which type of burner you build---the same number of BTUs per pound of propane burned is produced. (Assuming you do a decent job of building and tuning the burner.)

So the how much heat you can trap in the forge has a major factor in fuel efficiency. Another is size; folks generally want to build way too large a forge not realizing that anything you heat up that is more than you can work before it cools is just a waste of fuel and steel. (For example a sword forge for a beginner should heat 6-8" at a time!) You will want at least 2 1" layers of kaowool plus all the other stuff mentioned in the gas forges 101 thread.

I've run aspirated burners from temps over 100 and temps below freezing, dry, wet and 700' to over 7000' altitude. Tuned them as seemed best. My forced air burner hasn't had such a wide usage---hard to run an extension cord on a campout. I usually budget US$2 an hour for propane; a bit less for some things and a bit more for others.

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5 hours ago, ThomasPowers said:

I usually budget US$2 an hour for propane; a bit less for some things and a bit more for others.

That's a respectable goal.

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7 hours ago, ThomasPowers said:

 I usually budget US$2 an hour for propane; a bit less for some things and a bit more for others.

Number of burners, burner size? Forge size? (I'm assuming these factors should affect how much propane you burn.)
What does the propane cost in your area? I did a bit of research recently and found out it makes a big difference what size tank you have. if I rememeber correctly, it cost ~$25 to fill a 2kg tank (not really an option for a forge), and ~$35 to fill a 11kg tank.

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3 hours ago, G-son said:

Number of burners, burner size? Forge size? (I'm assuming these factors should affect how much propane you burn.)
What does the propane cost in your area? I did a bit of research recently and found out it makes a big difference what size tank you have. if I rememeber correctly, it cost ~$25 to fill a 2kg tank (not really an option for a forge), and ~$35 to fill a 11kg tank.

It's going to be one burner. Burner size will be your typical 3/4" setup. As for forge size I am still trying to figure out what I am using for the body. I have never welded before, though I might know someone with a welder. However doing the project with as little welding as possible for now would be a bonus. That being said the plan is to keep the working space to 350 cubic inches or just slightly under that. I am looking to find something that is 10-12" long and work from there.

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4 hours ago, G-son said:

~$35 to fill a 11kg tank.

Last small 20 lb. 9kg tank I had filled ran just about $20 and prices have fallen quite a bit. We use a lot of propane here though and that effects prices. A 2 or 3 kg. tank would be impractical as it'll freeze up, a 20 lb. tank is only good for an hour or two before freezing, I don't run less than a 40 lb. tank with the expectation it'll last more than a few hours.

1 hour ago, Rath said:

However doing the project with as little welding as possible for now would be a bonus.

You don't need a welder at all, everything can be: bolted, screwed and pop riveted together. 

Frosty The Lucky.

 

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There is another important reason for many people to avoid five gallon "barbecue" size propane cylinders. Twenty years ago, when small refillable cylinders were being updated by law, some states decided to include an additional safety feature in their new valves, which quite effectively limit how much propane flow they allow, totally ruining them fore use in heating equipment--beyond heating steaks on the barbecue. As with so many sneaky political decisions, the states that went for this "safety improvement" have no desire to trumpet what they did, making small propane cylinders a nasty surprise, without remedy in some areas of the USA :)

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