Resurrection of a BN2 Heater for Pearl

Very Cool!! 

Very impressive with the relays and the diodes. Good luck making heat. Wish I had some in my garage now...

I know who the Fairy Godfather is...

Gordon , if Bill Nye the Science Guy screwed Professor Peadbody you would be the love child! Nice touches with the Tiffany lamp and personal photos in the laboratory.

you are the quintessential Steam Punk renaissance man,

Well Played Sir, Well Played!

During the Thanksgiving school break for my boys we headed south and along the way stopped in Huntsville, Alabama at the NASA Space Center.

 

I'd swear they had that same setup only it was used to power part of one of the rockets that put man into space.

 

Gordon....come clean on what you are really planning here.

If you look closely, on his bookshelf you will see a book titled "How to build the Space Shuttle out of household appliances, vol 1-3."

Go Gordon, go!

Edit: Bring a fire extinguisher, just in case.

Ted

All the ones I played with had this sticker on them -

 

Gordon, that is one clean, almost brand new looking heater.  Nice.

 

They make great heat and will run on almost anything.  I have a friend that uses one to heat his garage space with old gas pulled from the junkers that show up at his shop.

 

That going to keep you warm for sure.

Phase one of the fuel system test went poorly, at best.  The pump pumps ok, but the fuel filter leaked like a sieve.  Found that the o-ring seal must have petrified about 20 years ago so made a quick trip to my local ACE hardware for a new o-ring and that is now sealed.  

 

Then found that the fuel pump, while pumping nicely, is also allowing fuel to pass through when turned off.  Did a quick dismantling and now have to consult my service manuals to see what kind of valving goes on in there.  There's only one valve, so how hard can this be??

 

The good news is that there have been no explosions, nor have there been any fireballs detected by the two Jacks from the direction of the 11°F shop (thus far, anyway....).   Of course, it's still ealry into the test process, here.......

Gordon , i have a b2 model and those pump/draw fuel UP from the vehicles gas tank,[they also have a return line that drains any excess fuel back into the fuel tank] so you might want to lower your fuel supply. That may eliminate your leak. Just sayin. Tom

Thanks, Tom......That's about what the service manual says, too......duh!

Progress!

Shhhhh.........Hear that?  The sounds of silence?

 

That's what you hear when you discover that ALL of the rubber diaphragms in the fuel pump and fuel regulator petrified years ago, even though they hadn't been in contact with gasoline in decades.

 

The fact that the pump worked at all is a minor miracle, but the output wasn't adequate to drive the regulator, causing me to suspect the regulator.  Opened it up and found the rubber diaphragms are both toast.  They're also unobtainable, so I'm looking for some Buna-N/Nitrile gasket sheet material (1/64" thick) with which to make some.

 

Now, THIS should be fun!

Oh boy Gordon! Can you use nitrile gloves?? Maybe?

Always wondered if those cheap Empi-Facet fuel pumps would work as replacement?

 

Have you tried:

http://www.germansupply.com/xc...mer/home.php?cat=376

You need a pump that supplies less than 10 cc per minute, more like 6. I'm sure that EMPI pump would be WAY too much volume. We are talking 12 ounces an hour here, less than a pint(more like 3/4 pint) an hour.

Danny:

 

I also have a later, so-called "Mitered" pump.  Can I assume that if I use one of those I don't need the regulator?  Also, is the mitered pump driven off of the fan contacts or can I just apply 12V and it'll pump?  If both of those are true, I may have a quick way out.

 

If not, does anyone on here know of a potential source of Buna-N/Nitrile rubber sheet, nylon reinforced (sometimes called "Calendared") and 1/64"  ( .0156" ) thick?

 

I could get by with a square foot, but will consider a larger sheet if available.

 

This stuff is commonly used in making carburetor diaphragms.  If I have to, I'll make up new ones and rebuild what I have.

 

Greg:  No go for German Supply, although surprisingly, they have some NOS regulators.  If they have been sitting for more than ten years (more than likely) then those diaphragms have petrified, too.  The one I have has never had gas through it and it's stiff as a board.

OK, tried out the Mitered pump and it's a solenoid-driven gizmo, too, so I would have to come up with a pulse generator to supply the pulse signal to it.  

 

Just fyi - these later pumps, while eliminating the fuel regulator, require a whole different heater fan assembly that has a set of contacts that open and close repeatedly to provide a pulsed, 12V signal to drive the solenoid fuel pump (like one of those clickety-clack "Facet" pumps). 

 

Might be easier to find some rubber sheet and build some new diaphragms......

 

Except for building diaphragms from scratch, the rest of the thing is greatly serviceable.  Everything comes from a past era when mechanical devices were expected to be serviced and rebuilt so that's a good (maybe GREAT) thing.  If soft, useable diaphragms were available it would take about ten minutes to replace them and be good to go.......

Gordon ,I seem to remember a fellow from Canada doing a refurb on one of these using some gas and oil resistant shelf liner from harbor freight to make some diaphragms . I think the write up is on the samba.

There were also some ready made new diaphragms in the samba classifies or on ebay two or three years ago . Also German Supply in Toronto has some parts for them.

Metered pump is only for the later BN-2 which has points so it pulses the pump on and off, kind of like a solenoid. The early pump has its own contacts but needs the regulator to fine-tune flow. From what I have read one diaphragm is thicker and meant to be kind of hard but the other is supposed to be thin and soft.

Well, these things MUST have been designed by a German.  Very precise and WAY more complicated than they need to be.  I spent all day looking for the diaphragm material and got a "Diaphragm 401" graduate education along the way.

 

Bottom line:  I can potentially find the bare material, but the regulator diaphragms are both formed material, meaning that there is a flexible ring, heat/pressure molded into the middle of the diaphragm to allow longer excursions of the center (rivet) sections.  This simply isn't a flat piece of rubber in there, it's way more complicated than that.

 

I have found a place in southern New Hampshire which is equipped to make new diaphragms out of the same type material as the originals, but then the center hardware becomes the issue - you usually can not re-use the stuff that's there, you have to source new stuff, especially the brass rivets - not easily found, and people have been trying to source this stuff, unsuccessfully, for ten years or so.

 

If your head is already spinning, mine has been spinning since about 11am.

 

I'm seriously thinking of approaching this from the opposite direction: The amount of fuel supplied to the glow-plug sprayer is known and measurable.  The delivery pressure is quite low (under 1 pound) so how about finding a fuel supply that matches THAT, without trying to re-create something with little or no market that involves a lot of start-up capital and running around??  Eliminate the entire existing fuel supply for something readily available that works?

 

THAT is going to be my focus for Monday, once people get back to work and I move on to my "Gas Heater 301 - Basic Operation and Fuel Delivery" course.  

 

Funny - The last time I got involved in something like this I had a bunch of Engineers doing the leg work for me......... 

Maybe a pump from an old oil burner? Might try ringing up some old oil burner/boiler repair guys and see what they say.

Nope.....Think in the opposite direction.  More like a model airplane fuel delivery system.  

 

This thing has a single 30mm jet which squirts gasoline at a specified rate onto a stainless steel screen which is heated by a glow plug until combustion can carry itself and then the glow plug is turned off.  The rate of fuel delivery is constant (unlike the later units that have a slightly variable flow).

 

I'll be researching low volume, low pressure fuel delivery systems over the weekend and look into both directions (what I've just described and also sourcing new diaphragms) next week.

Be careful.  During testing of a BN2 i had it dumped some fuel out the exhaust onto my workbench and then fired up.  All happened within seconds.  Luckily I put the fire out quickly.

Gordon, this is why I kept thinking about a microcontroller. Get rid of all the old German circuitry, use the overtemp sensor still with a fuse and use the existing thermoswitch to let the microcontroller know when to turn on and off. Two relays for the motor, low/hi speed. One for the fuel pump, one for the glow plug. So four relays and an Arduino. Easy and cheap. I just bought an Arduino book to learn the code. Doesn't look much different from the code I was writing 30 years ago.

 

Also, a pulsed on/off switch could be easily set up to run the later style fuel pump. Then you could vary the duty cycle and/or the pulses per minute and control the heater easily, with a knob(potentiometer). At that point you wouldn't need the old pump or regulator at all.

It's amazing to read Danny's advise/suggestions and realize how pathetically limited my knowledge is...since I didn't comprehend a single thing he verbally diagramed!!!

Carl, when I am done, it will be simple, solid state, and cheap. And it will flat out work! On-off switch and a knob, dead simple, more heat turn clockwise, less turn the other way.

 

The heater in my Spyder works great but is on/off only. I want to get both heaters going solid state and use the other one in my 911. Headers for that are WAY cheaper than Stainless Steel heat exchangers(911 version of heater boxes). Well over 2K with a decent muffler at today's prices. I can get a muffler and set of headers for about half that.

http://www.banggood.com/Wholes...B-Board-p-68537.html

 

This is an Arduino board, smaller than a pack of cigarettes. An add-on relay board is about another 3 to 5 dollars.

"on off switch and a knob"...

Now that I comprehend !!!!

Gordon now you've done it! I'm going to take back a 70 type 2 steering box i never used and trade it for as many old bn2s I can get. hopefully if I follow the great tips and your rebuild story I can get some heat into my Speedywith no top. it's only getting to 70* today but mornings and nights are colder,(should help with defogging windscreen too).

you guys are great!

 

Danny I've looked but didn't note the model heater you a working on is it a Bn2 as well?

thanks

Danny has a later model BN2, which has no fuel regulator and uses a so-called "Mitered" pump.  This is a really interesting bit of german design:  

 

The pump is a solenoid driven thing that makes one pump stroke each time the power is pulsed.  There is a tiny gear reduction box connected to the main air blower shaft that closes a pair of points once for every 31 revolutions of the blower (fan).  Every time the points close the pump does one squirt of gas through a jet, onto a stainless steel screen which gets heated by the glow plug to combust the gas (So while there is a flame, it's kind-of like the flame in an infra-red heater - it stays close to the S/S screen). 

 

So you see, the fuel delivery is not a continuous stream, but a pulsed stream.  The blower speed can vary by whether or not the car is running, whether it is a cold start and so forth.  The air blower provides warm air to the cabin, but also provides input air to the combustion chamber (via a second fan on the same shaft) so coupling the fan speed to the fuel pump action makes sense (I guess) because it varies the amount of gas to match varying amounts of combustion air (like maintaining 14.7 to 1 in a gas engine!)  The fan runs between 1,940 and 2,200 rpm so divided by 31 gives you a pump pulse rate of between 62 and 71 pulses per minute.  Set up a pulse generator for the pump and you're good to go.

 

However!  I don't think varying the pulse rate to the pump will change the heat output.  All that would do is vary the mixture for combustion (lean/optimum/rich).  We'll get to heat output in a minute.

 

MY BN2 is an earlier unit and works a bit differently.  My pump is also a solenoid unit and pulses, but is designed to run continuously (the rate, when running, sounds about 2 times per second, but it slows down once pressure builds up at the regulator).  It is connected to 12V via a relay, and is NOT run off of a pulse signal from the fan.  

 

The pump output goes to a fuel regulator (now made of unobtanium) which converts the pulsed input stream (of about 1 pound pressure) to a continuous output stream of slightly less than the input pressure.  That's all it does - smooth out the pulses to a stable, low volume/pressure stream.  That stream then goes through a 30mm jet (looks exactly like a carburetor jet) which shoots a continuous stream of gasoline onto a stainless steel screen which is heated by a glow plug to combust the gasoline.

 

OK, so how do you vary the amount of heat in the cabin if the heat output of the unit is continuous??  Simply turn it off.  There are several different heater controls for these units, and all that I have seen are simple timers that run the heater for a while, then turn it off for a while and then turn it back on at a set interval.  I had thought that some of them worked as a thermostat  with a bi-metal strip but those would be impractical due to road vibration so those clever Germans just made a timer instead.  And it works.  Just like turning the main power switch on and off at set intervals.  It would be simple to get a cheap, 12V electronic thermostat and wire it in with a relay, set it to whatever you want and it would cycle the heater for you.  I found this one a while back:

 

http://www.amazon.com/12V-Digital-Temperature-Controller-Thermostat/dp/B00C4TEEF2/ref=sr_1_1?ie=UTF8&qid=1388603923&sr=8-1&keywords=12+volt+thermostat

 

so that's where we are right now......

 

Danny!  Can you measure the size of the fuel jet in your later model heater and let me know the size?  I'll go out and measure mine with a torch drill and see what it is, too - probably be a good idea not to trust the numbers on the side of it.......

Thanks Gordon, Ill take the pic of yours as something to go by, apparently they're in a pile stored in a couple of buses, so hopefully Ill get a complete one that is relatively newer.

Danny:  I pulled the jet and could not get a .0225 (#74) drill through it so it has to be closer to 1/64" (.0156") but I don't know for sure (don't have a drill that small).  Just for reference, 1/32" = .03125 so it's somwhere between those two.  Maybe 30mm stamped on the side is accurate?  Doesn't 30mm = .0118?

 

If I find something smaller and calibrated I'll re-try and let you know.

 

BTW:  the fuel consumption for my version of the BN2 is 10.7cc's - 12.7cc's in 2 minutes.  

 

Not a lot of fuel......

 

Hell, I got 15 cc's of Gamma Globulin into my arm before heading to Central America, once!

 

So I guess I can take one of two roads, here -

 

1.  Try to find some way to buffer (regulate) the pulses coming from the old-style fuel pump that can cycle itself without a pulse generator - hopefully, something adjustable to down below 1 pound of pressure, or;

 

2. Build a pulse generator, run the new-style pump at a set rate and potentially try running a different mixture jet. 

 

I'm open to any other ideas.......

Gordon, reading your description of how this thing works reminded me that Rockwell made a very similar device back in the sixties. Maybe you can use a fuel system from one of those. They should be easier to find as they were American made and more widely distributed.

 

Here's an old in-house training film they made to explain the operation:

 

http://youtu.be/RXJKdh1KZ0w

 

Just to clarify, I have one of each version of the BN-2. The early one with Hardi pump and pressure regulator is in my Spyder.

 

I also have a late one with a pulsed/timed/metered pump and no regulator that I'd like to use in my 911 some day, if I can figure out how regulate the heat.

 

There is no jet on the late one. There is a permanent metal 90 degree fuel manifold that drops the fuel onto the glowplug. It has a 5/64" inside diameter. So just a hose directly from the pump to this fitting, that's it.

 

And I did say above that these things need about 6 cc's a minute, which is the same as 11 or 12 every 2 minutes, no?

 

 

Sacto Mitch:

 

I actually have an early version of the Rockwell Retro Encabulator but I've set it aside in my garage until I can find a new reversible ferangulator hub. These early Encabulators burned through the hubs and the decapacitating kretschmer bearings like they were made of trasturian alomentium!

 

Last time I had it up and running it was attached to a Hungarian made Salad Shooter and unfortunately it was so powerful that it drove the carrots it sliced through the drywall behind the kitchen counter and they are still imbedded in the insulation.

 

Well that was when my wife insisted the the whole 700 lb., solid state Encabulator be moved to the garage and out of the center of the kitchen.

 

I think the next application will be either to the pump on our well, (If I can find the right hub replacement) or to my children's pencil sharpener if the particulator housing can be matched to the oscillating distortion modulator arm.

 

Wish me luck! 

I liked this one much better, Bob and Mitch!!!

 

http://www.youtube.com/watch?v=Kbkuz_j9Fbc

Gordon, I think some of these guys are snickering behind your back. Next time I see BobG, I'll swat him for you.