Heisler Burner Construction
Nelson Riedel, Nelson@NelsonsLocomotive.com
3/4/2010, last updated 08/29/2010

This page describes the construction and plumbing of the burner including:

  • Fire Pan

  • Burner Nozzles

  • Fuel supply plumbing

  • Atomizer and Blower plumbing.

The oil fire involves the oil supply, steam or air supply for the atomizer function and steam or air supply for the blower.  On the shay, once a good setting is found for the oil valve and atomizer pressure little adjustment is required (the atomizer feed is equipped with a regulator).  However, the blower valve requires frequent adjustment to compensate for changes in boiler pressure.  A blower pressure regulator has been included on the Heisler to (hopefully) reduce the need to monitor the blower pressure closely. 

 The diagram above shows the layout of the burner and associated plumbing.  The oil feed is in the lower part of the drawing with the pipes in black.  The steam- air system is in the upper part of the diagram with the pipes in red.  During startup the valve to the steam manifold is closed and an air line is connected to the air input quick-connect fitting and the associated valve opened.  Once boiler pressure has built to about 40 psi the valve to the steam manifold is opened and the external air valve is closed.  The check valve in the external air feed is to prevent steam from entering the air line and air compressor should I forget to shut off the valve.   

Update 8/6/2010:  The first few tests of the burner revealed that the atomizer steam didn't seem to be equally divided between the two burners.  This may be because the burner nozzles weren't identical.   The burner system was redesigned to use two regulators and two heaters.  Rather than completely redoing this page photos showing the new design were added to the end of the page. 

Fire Pan: The fire pan fabrication pretty much followed the design drawings in the Burner & Fire Pan Design page.  The baffle support is a little different to match the material I had on hand.  The coil of 3/16" stainless tube is the atomizer steam heater.   The fittings through the side for the stainless tube are 3/16" tube compression to 1/8" NPT brass fitting, males on the outside and females on the inside.  The vertical extensions to the sides are ~20 gauge steel and fit inside the firebox to better seal the fire pan-fire box joint to prevent flashes of fire coming out around the joint. 
This shows the burner end of the setup.   The oil feed is into the end of the nozzles using 1/4" tube. The atomizer steam input is into the side of the nozzles using 3/16" tube.   The valves allow the steam to be turned on or off to each nozzle. 
This shows how the oil lines run under the fire pan.  The  1/8" X 1/2" bar holds the oil lines close to the bottom of the fire pan to provide warming of the oil.  There are 1/2" diameter 1/4" thick spacers under the ends of the bar.

The burner supports were steel on the design.  I choose to use some 1/4" thick aluminum angle when I got around to actually doing the fabrication.  The part of the angle against the fire pan base was milled down to 1/8" thickness.  The front of the burner nozzles were aligned with the outer edge of the fire pan side.   
The sides and bottom of the inside of the fire pan were coated with ~ 1/8" thick layer of refractory cement.  I did this on the first shay fire pan but not on the last one.  I got really strong encouragement from some of the west coast live steamers to do the coating.   They could not explain why.   I though the use of firebrick on the prototype fire pan was to keep the fire pan from rotting away due the the intense heat.   Maybe there is something more to it.   The coating was applied using a 1" wide kitchen spatula.
Spark Plug:  The spark plug hole  is drilled through the upper corner of the channel.  This plug uses a 9/16"-18 thread.   The plug is at about 30 degree angle with the horizontal.   Part of the channel directly above the plug is ground away to give clearance for the plug body.    this threaded hole eliminates the need for a retaining device as originally planned. 


The oil feed plumbing is shown above.  The fuel valves on the left side are McMaster-Carr # 4995K11 brass needle valves.   Shaft extensions with knobs are required for these valves. The red disk is a Briggs & Stratton lawn mower fuel filter purchased at Tractor Supply.   The fittings each side of the filter in photo above are coolant quick connects from McMaster-Carr (# 6739K52, #6739K35 & #3739K91).

Update 8/29/2010: .   After  few hours operation the seals in those coolant quick connects swelled and then started to disintegrate ----- guess they're not compatible with diesel. 

The male fittings were replaced with 1/8" NPT nipples and the female fittings in photo above were replaced with the barbed hose to 1/8" NPT tight seal adaptors (McMaster #5440K104) shown on the right.  These are as easy to use as the quick connects if you have a  1/2" wrench handy.  End Update.


This shows how the fuel plumbing fits on the frame.  The oil line is in the right rear corner of the tank with a right angle shutoff valve on the end.  The quick-connect to the rear of the filter connects to the shutoff valve.  The oil tank must be easily removed to gain access the electrical compartment below the tank.  The shutoff valve and quick connects make it easy to disconnect the fuel line.  The line passes right to left via the 1/8" brass pipe which will be just in front of the electrical switch panel. The current plan is to make a hump in the rear of the floor plate to cover the pipe.    

Update 3/27/10:  After the electrical compartment was constructed the location of the fuel line above the cab floor stuck out like a sore thumb.  It also became apparent that the fuel line would be prevent the use of operating cab doors.  The fuel line was routed above the cab floor to permit the fuel line with valves to be lifted out as a complete unit.  After rethinking this I decided to hang the fuel line below the frame sides.  The new configuration is shown above ---- note that the left side frame channel is off giving a better view of the fuel valves.  The fuel line can be unscrewed from the elbow behind the valves when it is necessary to remove the valves.  The fuel line quick connect fitting is lower in this configuration so the mating angle quick connect on the forward end of the fuel filter will be replaced by a straight quick connect.    The cab floor can now be a simple flat plate. End update.

The Regulators: Both the atomizer and blower feeds are equipped with Clippard Regulators;  model MAR-1-2 (0-20 psi) for the atomizer and MAR-1-5 (0-50 psi) for the blower. The regulator ports are threaded 10-32.  That is the blower regulator on the right.  The input is at the rear and the output on the side.  A 1/4"-40 to 10-32 reducing nipple is used for the input and a 10-32 to 3/16"-40 nipple is used on the output.  The pressure gauges are McMaster #4112T13 modified by tapping the inside of the input fitting 3/16"-40.  The siphon tubes are 1/8" with 3/16"-40 bushings silver soldered to the ends.

An abundance of testosterone requires that one of the regulators be disassembled to see how it works.  A more important reason is that the hi temperature version of these with the Viton seals requires an order of at least 10 so I decided to purchase the low temperature version and change the O-Ring seal myself.   

Disassembly is straight forward once one can get the plug on the right end off.  That blue stuff on the threads is a sealer that works really well.  I grasped the body in the lathe 3-jaw chick and attacked the thin edge of the pug with channel locks.  The channel locks left their mark but I was able to get it apart.

The main valve is in the plug on the left side.  The valve is opened by pushing the needle thing to the left.   When assembled, the needle fits into the hollow rod of the piston which forms a relief valve.  The space between the piston and the main valve is at the same pressure as the output (which is via the half of the 3/16' union screwed into the side of the cylinder).   The piston balances the output pressure against the main spring (the heavy one which is controlled by the adjustment screw on the far right.)  If the output pressure is too low, the spring will force the piston to the left which will in turn push the input valve open.  Pressure will build until the pressure below the piston matches the spring force above the piston and the input valve is open just enough to allow the inflow to match the outflow.  If for some reason the output pressure gets too high (such as when the pressure setting is reduced and there is very little flow) the piston will move to the right far enough to open the relief valve and allow the excess gas to escape through the hollow piston rod and out though a hole near in the right end of the cylinder.

There appears to be a thin rubber seal on that relief valve and I suspect there is also a similar seal on the main input valve.   I can't replace those seals but suspect that the valves will still work even if those seals are destroyed ---- they'll be metal on metal valves which might have small leaks which won't be a problem with this relatively high flow application.  The big O-Ring could cause a big leak if it was destroyed so I replaced it with a #013 Viton O-Ring.

I noticed that the O-ring had been greased.  That grease will probably be wiped out by the steam flow so it will be necessary to lubricate these regulators periodically ---- a couple drops of steam oil into the left side of the steam manifold via one of the plugs in the top should work.

One last point --- the regulators can be ordered with different pressure ranges.  I suspect that the only thing different for the different pressure ranges is one or both of the larger springs.

Photo above shows all the components laid out on the basement floor.  The wrench at the corner of the fire pan is a prop holding up the pipes for the photo. 

This shows the installed steam-air parts. The upper regulator and gauge are for the blower and the lower regulator and gauge are for the atomizer. 

The fireman also has to control the water so this side of the cab will be quite crowed with those controls. 

The black thing above the air input quick connect is the lubricator.  The lubrication tubes must also be run from it so things will really get crowded.

The pipe from the blower regulator goes under the upper frame bar and disappears.  In fact, it follows under the bar to near the front of the locomotive. 
This shows the front part of the blower pipe where it connects to the side of the smoke box.  Most of the pipe in this area will be hidden by the exhaust pipe.

Those fittings below the blower pipe connect to the feed water heater input.


This photo shows the underside of the fire pan and associated plumbing.    Note that the drive shaft is close to the  bar that holds up the oil pipes.   It is doubtful that the front of the middle truck will flex up enough to cause the driveshaft to rub against the bar.  However, no damage will be done if it rubs once in a while. 

The fire pan was installed and removed several times during the construction of the associated plumbing.    The driveshaft must be removed to get at the fire pan.  The pin in the universal to the rear of the fire pan is pulled which will allow that universal to come apart and the driveshaft to be pulled out of the slip joint below the front of the fire pan.   The four 10-32 socket head cap screws are removed to allow the fire pan to drop.  The baffle plate sticks up about 8" so the engine must be on a rack or stand that is open between the rails so that the fire pan can drop down below the rails.  The extensions on the sides that fit up into the fire box makes it easy to align everything when the fire pan is installed.

Update 8/6/2010:   As mentioned above, the system was redesigned to use two atomizer heaters and two regulators.  The following photos show the changed design.

The photo shows that the atomizer valves between the burners have been removed.  The atomizer feeds for each burner run midway down the sides of the fire pan and then inside to the heaters via a compression elbow. 
This photo shows the two heaters.  The heaters are stainless steel tubes.  The inputs to the heaters is via  compression fittings in the left side.  The fittings on each end of the heaters are also brass compression.  (The through the pan side fittings use 1/4" compression fittings with 1/8" NPT through the side.)  The two elbow compression fittings on the lower part of the photo are the fuel feeds.  
This photo shows how the second regulator and gauge were added beside the first regulator.    (The plumbing is getting a bit crowded in this area.)

  This wraps up the burner and associated components and plumbing.     Check out the Burner Operation page for information about how the burner actually works.

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