View Full Version : OT,or not,building propane cooker/fryer

03-07-2009, 01:24 PM
Hey Ya'll, I have a cast iron burner that came from an old natural gas hot water heater that had been in a flooded basement. I junked the WH but saved the burner cause it looked like it could still be usable for some home built project. I also have a propane regulator that hooked up to a 20# bottle on an old camper that was junked, it has a blue plastic cap on top that when removed reveals the regulator is adjustable. I've had these items for years now. Ya , I'm a pakrat & also poor so I never throw out something I think I might find a use for "someday". :rolleyes:
So here's the plan, I've allways kinda wanted a propane cooker for frying fish , chicken, etc. Plus I'm very interested in the black oxide treatment for my shop built tooling as recently shown in a very good and impressive thread by I think, ClintonH.
I have a pretty good selection of scrap iron & I'm a weldor, oxy/act, stick , small mig , so whipping up a burner/pot holder stand is no biggie but the specifics of the propane burner set-up are unknown to me.
So here are the questions I have with what little I know about the deal so far, oh and by the way I've searched the net for hours trying to find answers to my questions with very little sucess which is why I come to this wealth of knowledge.:D
1 What pressure should the regulator be set at? From what I have read so far I think this is a hi pressure reg. 0-20 maybe 30 psi ?
2 What size orfice should I have & is it placed at the regulator out put or in the "bell" at the burner?
3 To control the burner output can I just put a ball valve in the line or do I need an adjustable lo pressure regulator after the hi pressure reg. ?
4 And my last question for now, I know this burner had & I've seen on other similar burners, a slotted plate on the "bell" of the burner that is rotated to control the amount of air drawn into the back of the burner. The original plate on this burner was rusted away due to time spent in the flooded basement so I'll have to make a new one which is no problem but knowing exactly what it's for & how to properly adjust it is.
Lastly before everyone tells me I can buy a fryer like this cheaper than I can build it I have to say I would like to make my own for the learning experience plus thanks to the downturn in the economy I don't know if I'll still have a job from one day to the next right now & can't afford to spend money for something I just want & don't need.
Thanks in advance to anyone who tries to help me out, it is appreciated, Rick

03-07-2009, 02:00 PM
The propane regulator is a pretty primitive device. It has a fixed orifice and a known pressure range set by the manufacturer. The combination provided a known volume of gas to flow. The volume of gas translates to BTU. Chances are excellent that old BBQ didn't have anywhere near the BTU of your water heater so the total BTU you get will be what ever the BBQ was designed for.

The pressure needs to be less than the vapor pressure of the propane otherwise what you have is an open pipe. The diameter of the orifice can be enlarged to provide more BTU. Understand that the most BTU achievable is when the orifice is the same as the hose it is attached to, so you might just want to remove it entirely and see what you get. If you have more than you need you can reduce it.

The regulator does two things, BTW. It is a flow control valve so you can adjust the flame size, and it is a limiter to manage the maximum size the flame can be. Running up the pressure will increase the volume, but if the air mixer cannot handle the higher volume you will get a yellow flame.

Finally - if the flow rate is too high the cylinder and all attached components will freeze and you may not be able to shut off the gase.

03-07-2009, 02:45 PM
Adding to dp's reply

Question #4 And my last question for now, I know this burner had & I've seen on other similar burners, a slotted plate on the "bell" of the burner that is rotated to control the amount of air drawn into the back of the burner. The original plate on this burner was rusted away due to time spent in the flooded basement so I'll have to make a new one which is no problem but knowing exactly what it's for & how to properly adjust it is.

The bell you refer to, is a lead taper into a venturi throat.
The orifice you refer to is mounted so that the fuel gas jet will draw air into the venturi so that the fuel gets mixed with air in appropriate quantity within the venturi throat and has time to mix reasonably well on its way down venturi and into the burner ports.

The plate is an adjustment so that too much air is not delivered.

Too much air and the flame will have lean mixture problems and dance away from the burner and sometimes blow out.

Not enough air and the flame will have rich mixture problems and all that may imply.

Question #3 & #1
To control the burner output can I just put a ball valve in the line or do I need an adjustable lo pressure regulator after the hi pressure reg. ?

Propane burners are regularly controlled by a low cost regulator deliberately built for the task.
The pressure output of a stove regulator should be somewhere around eleven inches of water, GAGE pressure above one standard atmosphere.
Before you build a super stove here are a few numbers.

11 inches water gage pressure is something like 0.3974 psiG

14.696 psia is the level one standard atmosphere.
29.92 of Hg is the level of one standard atmosphere.
33.899 FEET of standard water is the level of one standard atmosphere.

14.696 psiG will be 33.899 feet of standard water above a standard atmosphere.
1 psiG is the level of 27.6804 inches of standard water

Question #2
What size orfice should I have & is it placed at the regulator out put or in the "bell" at the burner?

You want a high burn rate of about 40,000 Btu per hour in the usual home fryer stove.
Many old water heaters and barbecues were at this level on natural gas.
Propane orifice will be smaller than NG orifice for the same heat rate.

That means your "stock" orifice was/ is too big for propane.

I will look it up and add a suggested starting size later than now.

Mike Burdick
03-07-2009, 03:38 PM

I don't know how a water heater burner will work - looks like others will have specific answers for that. However, you can buy specific BBQ burners inexpensively - here's an example...


Regardless, I think building your own stove would be a great project! For design ideas, wander around the stores and check out the models and features you like and take detailed notes? Maybe you could even add a smoker on the side! I have s stove right outside my kitchen on the deck and we use it a couple of times a week throughout the year - come rain, snow, or sleet!:) Clean-up is so much easier!

If you make one, be sure and post back with pictures!

03-07-2009, 03:45 PM
A couple of years ago I designed a new house for a guy who tried to cook a turkey in a hot oil cooker in his garage. Garage and house bot burned to the ground. Gary P. Hansen

Your Old Dog
03-07-2009, 03:46 PM
Look for an old propane grill at the side of the road and scavenge the regulator. It will be good for a 20 lb tank. That setup on most grills is 33,000btu which should be good for your needs. Don't know the specifics on the little natgas/propane brass orifice thingy. You will have to braze the pin hole shut and and redrill it to propane specs because no one will sell you a new orifice due to regulations. I wanted to re jet a wall furnace unit and no one would sell me one.

03-07-2009, 04:28 PM
Thanks men for the info so far & to others, keep it coming. I'm going to take the burner in to work monday & hit it in the blast cabinet to knock off the rust. Then when it looks a little more presentable I plan to post pics of the burner & regulator I have so maybe it will be a little clearer what I have already & plan to do with it.

DP, the regulator isn't from an old BBQ. It came from a camping trailer with a 20 # LP bottle on the tongue, then the regulator I saved & inside the camper was a 3 burner cooktop, a propane furnace & a couple of gas lights (you know , like a camp lantern with those tie-on mantle thingies). I think it should have more output than the average BBQ but I'm no expert so can't be sure on that. Now if I still had that cooktop I could just use the burners from it but at the time I was junking the camper (7+years ago) a friend showed more interest in it than I had at the time so I sold it for $25.00.

BTW I was reading an old thread on the Shop Floor Talk bbs & a guy said he made a fryer & recomended an old waterheater burner as an excellent choice ? Unfortunately there were no details of his build :( Oh , & the friend who got the cooktop moved to Colodaro & we have lost touch so no chance of me seeing it again. Rick

Roy Andrews
03-07-2009, 04:45 PM
i know you don't want to buy anything but these can be found cheap at garage sales or you may already have one. i have made a number of fryers and my current bluing pot all use a propane weed burner. unscrew the head and put on a 90 and a short length of pipe and screw the head back on. make a mount to hold it so that it points up and is steady.

as far as what you got. put a valve after the regulator and just hook the gas up to it, cover about 50% of the air inlet and light it up. adjust the amount of air until you get a stable mostly blue flame. throttle it with the valve. you said the burner was for nat gas but there should be enough air adjustment for propane. when you light it have your shirt pulled up over your head and chant "i am cornholio" it always seems to work better that way and you wont burn off all your hair.:D

J. Randall
03-07-2009, 04:45 PM
Rick, I have fried a lot of fish on a rig like that. You very well may have enough regulator. I can tell you I have tried a grill regulator in a pinch a couple of different times and most just don't have enough flow. A small ball valve works great to regulate your flame. For fish you need the oil to run between 365 and 385 degrees, get over that and you will burn the batter and contaminate the oil.

03-11-2009, 10:10 PM
Well I took the cast iron burner to work & sandblasted it, when I got it home I slobbered it up with some flat black spray paint I had just to keep the rust at bay for a while. I hooked the regulator to my 20# lp tank ( the reg mounts directly to the tank valve outlet, I think they call it a "pol" fitting ? then fastened directly to the regulator is a ball valve followed by an 18" hose, ( ya it's a proper propane hose, says LP right on the hose ends, it came with the regulator. It just so happens the burner was already tapped with a 3/8 npt female thread which allowed me to fasten the 18" hose with 3/8 npt male ends. Just for a test burn I had no jet/orfice of any kind & I still haven't made that rotating air control thingie for the back of the burner yet so it was wide open.

WELL, I opened the tank valve fully & opened the ball valve a hair while holding a lighter to the burner & viola , it lit right up & I'm still here to tell ya'll 'bout it ! ;) With the ball valve barely open I had a small blue flame all the way around the burner , this was good , but if I open the ball valve some more I get a big , lazy , mostly yellow flame ( little blue at the base but mostly Yellow. With the ball valve all the way open it was WAY BIGGER & PRETTY MUCH ALL LAZY YELLOW.

I adjusted the regulator through it's whole range to pretty much no effect & used a piece of cardboard as an air limiting device on the back of the burner once again to pretty much no effect. So I'm thinking too much gas, I need a jet/orfice on the end of the hose at the back of the burner. Anyone think I'm on the right track & if so what size jet as a starting point ? Rick

03-12-2009, 12:00 AM
To know what size jet you need, first you need to know the output pressure. You mentioned it came from an RV? Then it's almost certainly 11"W.C., same as a BBQ, btw.:D The orifice size depends on the tube diameter, as well as the pressure level. It sounds like what you need to make is a "gas accellerator"

You might want to read this (http://books.google.com/books?id=nHkpb4cCKvQC&pg=PA23&lpg=PA23&dq=gas+accelerator&source=bl&ots=vZ6QG2Da).

Oh, for those wanting to build burners - check out Tejas Smokers. They sell burners, venturis, regulators, and everything else under the sun.

03-13-2009, 11:13 PM
The Burner you have will probably work. You need an orfice (0.032) will work I would recommend an adjustable regulator set at about 20 psi. Then a needle valve in the vicinity of the burner connection for the flame adjustment. The air shutter on your burner can be cut from sheet metal with aircraft hand cutters or a cold chisel and dressed with a file.

03-15-2009, 12:03 AM
There is some debate on fish cooking temperatures. Some of this is due to the measurment methods. A lot of the cooks use the old long stem thermometers. Some of the commercial cookers have a thermocouple type probe. I use a Raytek Mini Temp laser and cook at 325F. The old kitchen match floating in the cooker until it lit worked for years. (Strike anywhere kitchen matches are hard to find today) The important thing is not the reading but correlating the reading to the results. The most common fish cooking mistake is overcooking it. I don't like raw fish and dislike over cooked fish even more. There are fundamentally two types of homemade fish cooker burners. The first is the old cast iron burner type like you have. The second is the jet type resembling a weed burner or in Texas Talk a Pear burner meaning (Prickley Pear Cactus). Some have recommended Ball valves and these will work in some instances but a needle valve will work better. As mentioned in my previous post an adjustable LPG regulator set at 20 psi working through a 0.032 orfice works good. LPG adjustable regulators are avaliable from the dealers for about $35. You can also skip the regulator and use a high pressure LPG hose with the needle valve. Another fly in the ointment came along with the new style Bottle valve. There are two types of the plastic screw on external connector. One is low flow and one is high flow. The best solution is to go to the large 100 lb bottle which has the old style valve and will accedt the old POL type fitting. The next problem that will come up when you start cooking is the wind. You need to provide a shield of some sort. I have a 55 gal drum with end removed and cut to the appropiate height at home. A piece of sheet metal flashing rolled and pop riveted together is used for the fryer at fish camp. Building fish fryers is kind of like reloading bullets you seldom save money but you have a lot more fun in the process. Good luck with your project!

Rob Peterson
03-15-2009, 02:11 AM
So I'm thinking too much gas, I need a jet/orfice on the end of the hose at the back of the burner. Anyone think I'm on the right track & if so what size jet as a starting point ? Rick
I think you are on the right track. But I suspect the yellow flame is actually from too little air, rather than too much gas.

There should be a jet/ orifice in the burner aimed into the center of the bell/ venturi (where the hose connects). The jet pulls primary air into the burner. If there is no orifice in the burner, or if it is badly damaged, it will dump fuel into the burner but not draw any air into the venturi and the flame will be lazy and yellow.

Don't worry too much about the orifice size. As previously mentioned, 0.032" (#67 drill I think) would be a good size. For furnaces and water heaters, where there is a defined manifold pressure, and a designed heat input, you would set the gas rate by choosing orifice size. But, for an open burner with a throttling valve in your control, the orifice size is less important as long as it creates a reasonable jet that will draw air.


03-15-2009, 03:00 AM
Hi Rick: I've built a few of these for various reasons: pancake breakfast for 300,(2 burners, 1/2 inch steel 24" by 48" with one inch strap steel welded around the circumference) the burners were in the middle, I had the butter and sausages on the left, fed them to the middle,put the batter on center left, flipped towards the right, and handed off. Boy, did we ever have grease!! I put a drain at the back of the "frying pan" after the first time. The turkey deepfry pot was alum. (I cooked five on Xmas day, too many friends, not enough beer), and I use the actylene reg to fine adjust your flame to a nice blue colour as this shows it is burning clean. I do like the circle burner for this task. Also adjust your bell air adjustment as you adjust the reg. Keep the flame blue! Also I have used peanut oil as the cooker but canola (Can. eh!!) oil is just about the second best oil for what you want. Regarding the freezing of the tank: I know of this but I do not feel you will have to worry about this as the only tine I had this was when I ran 2 (we call them) Tiger Torches at the same time off the same tank. Re the temp. for cooking: for the turkey, the oil had to "spit" when a drop of water was introduced. You have a good start. Wayne.

03-15-2009, 10:18 AM
Garage and house bot burned to the ground. Gary P. Hansen
Did they save the turkey?

03-18-2009, 08:18 AM
Hey Ya'll, I read the info at the link HTRN posted (Thanks HTRN) & dug up a spare tip for my littlest mig gun, .023 orfice. The O.D. of the tip is .250 so I dug up a 1/4" ferrell fitting, turned it down for a press fit in the end of the hose ( see there IS machining involved in this project) then inserted the mig tip & tightened the ferrell nut to secure it in the end of hose.

When I lit the burner there was a big difference in it's performance, nice blue flame, looked like I think a gas burner should look although a little smaller than I thought a burner this size should be capable of. It looked to have the BTU output of the average kitchen stove burner & I thought a burner of this size should do more so I increased the jet size in several small steps untill I finally stopped at .055. With the jet at .055 I have a much higher BTU output & with no air "choke" whatsoever I have a much larger & more powerful looking blue flame that every so often will show the tinest flash of yellow at the flame tips. I think this shows that I may have went a tad oversize on the jet a .055 but had no way of knowing that till I went over the edge so to speak.:rolleyes:

For now I'm calling it good to go & am beginning the burner stand/tank cart build. I want this rig on wheels so I can easily move it from storage in the shed to outdoors for use. Once I get it all built & operational I can always tweak the jet size now that I have a ballpark idea as to what the burner seems to need.

I want to thank everyone who has chimed in with help on this project so far & I'd really like to show pics of the progress but I got the camera out last weekend to take shots of the burner in action & found the little plastic latch on the battery cover broken :mad: The cover also contains the battery contacts so I have to try & find a way to repair it. Doesn't look like it's gonna be a easy fix & I really don't want to resort to a big rubber band , duct tape or something else even less high tech:eek: Rick

Lloyd H
03-19-2009, 11:54 PM
An orfice of 0.055 inches will give you 21131 BTU at 11 inch water column. I would think the water heater burner was about 30,000 BTU, for 30,000 BTU you need an orfice size between a # 52 (0.0635 in.) 28167 BTU and #51 (0.067 in.) 31357 BTU (all at 11 inch water column pressure) see:

Your Old Dog
03-20-2009, 07:31 AM
Lloyd, those are nat gas figures and he's doing propane. I searched for a propane chart but couldn't find it. Do you know if they have one?

03-20-2009, 08:00 AM
Lloyd, those are nat gas figures and he's doing propane. I searched for a propane chart but couldn't find it. Do you know if they have one?


scroll down the above page and download the "service man's manual". The manual will have a chart that lists orifice size and BTU output. I use this handy little book all the time at work.


Lloyd H
03-20-2009, 10:35 AM
Your Old Dog, the far right column is propane at 11 inches, look again.

03-21-2009, 10:14 PM
Forget the tables and the 11 inches of water. Buy a good adjustable regulator. Set it on 20 psi and use a small orfice to get the injection velocity up. This will pull inthe air. Use a needle valve near the air shutter to fine adjust the flame. This works! Another method is to buy a high pressure LPG hose skip the regulator and use full bottle pressure to the needle valve. This also works but is harder to adjust.