Van Wert Coal Stoker Technology
Or, at least, that pertaining to the Economy
Anthratherm, model VA13 A12.
Van Wert was one of the local anthracite coal burner companies based in
Peckville, PA. , and happened to manufacture the stoker I'm using for
home space and hot water heating.
It uses a 2-1/2" feed auger to move buck-sized Anthracite coal from a
holding barrel into the stoker.
The main feed auger is mounted into a cast gearhead assembly where a
second, shorter auger is positioned at a right angle, and redirects
coal flow into the bottom of the burner pot.
A single 1725 RPM motor is used for auger feed, combustion blower, and
ash knock-off. A 3-1/2" OD pulley sheave is mounted to the motor shaft,
and is coupled to the worm gear box via an AP35 belt, and 3" OD pulley
sheave on the gearbox side. This gives a gearbox input shaft speed of
approximately 2000 RPM.
The worm gearbox features a straight-thru input shaft
the combustion air blower
wheel, and a 600:1 ratio output shaft for coal feed and ash knock-off.
This reduction yields 3.35 RPM, and is further reduced using a #41
chain transmission system consisting of a 10 tooth sprocket on the
gearbox side, and a 21 tooth sprocket on the Van Wert gearhead side
(0.476 reduction) to yield a final speed of 1.60 RPM into a main gear
in the Van Wert assembly.
This main gear is directly coupled onto the right angle coal auger into
the burner pot, and drives a right angle gear set for the main feed
auger. The main coal auger side of the right angle gear pair has an
offset bolt positioned where the ash knockoff tie rod is mounted. Thus,
the main and 90° coal auger, and ash knock-off all operate at
same 1.60 RPM speed.
The blower housing is fitted with a
variable opening for air flow adjustment. Combustion air is routed
into a plenum which exits into the bottom of the burner pot along with
fuel from the 90° coal infeed auger.
Through experimentation I've learned it burns approximately 11.4 pounds
of coal per run hour, although the 'VA13' in the model number suggests
13 pounds/hour. This means
that, at approx. 8650 BTU/pound (figuring for burner
loss), it produces
heat on the order of 100,000 BTU, (or about 29.3 kilowatts) per run
I use 6 tons or less (through the 2005-2006 season it looks like it'll
be about 4-1/2 tons) per year, so, figuring for coal at $160/ton,
electricity at $0.08/kWH, and considering that power is power (a
thermal BTU isn't any different than the equivalent heat developed by
passing electricity through a resistance immersion heater) I heat my
home, and make hot water for $960 a year using coal, and it would cost
about $2400 a year using electricity.
This makes sense, because there is an approximately 3:1 ratio between
using a primary fuel directly, and using that same fuel to generate
electrical energy and deliver it to the point of use.
There is a rough 1:8 weight ratio between coal, and the ash it
produces, so I generate about 3/4 a ton of ash per year. This is used
for fill building up the south side of the property so there isn't any
This year started having problems with clinker formation, and
partially burned coal after having never had this sort of problem. The
clinker build-up looked as though it was sticking to the side of the
fire pot as it was assuming it's interior shape. I left the
receiver go empty, and let the fire go out during
Fool's weekend, and found out why - the fire pot is coming apart. Guess
this isn't too bad a run, insofar as the stoker was built in the
mid-1950's, but that is of little comfort as Van Wert has been out of
business for a number of years.
With any luck I'll be able to find a used one, but might end up needing
to fabricate a replacement, and that replacement won't be more than a
stop-gap measure. The original firepot appears to be cast iron
cast steel (based on the grain) and I'll need to make a replacement out
of concentric rings cut out of steel plate - no way it'll hold up.
Stoker coal usage tracking is done in a spreadsheet (OpenOffice Calc),
but I don't have it in a format that is clear enough to simply upload a
copy to share with the user community. Until I bite the bullet and
clean it up suffice it to say usage tracking has advantages. One
feature that comes in handy is I record when a coal delivery is made,
then use each month's run hours (and estimates for future months)
subtracted against it to determine when I'm going to run out of coal.
I don't know how accurate it is because the 2006-2007 season started
with maybe 1/2 ton (eyeball estimate) remaining in the bin, I didn't
start tracking until March, and summer usage is low so any error
makes a big difference - my original estimate was the last week of
August, and I made it to November (and still had about 200# remaining).
Its a lot easier to estimate 200# (about what it takes to fill
the feeder barrel) than a half ton so this year's estimate will tell
the tale. As it stands, based on tracked usage to date, and using last
years usage to estimate upcoming months I should run out of coal
While setting up an HMI computer for a project at work used a Fuji
PXR temperature controller to comminicate with (via Modbus RTU) for
testing, and to get a better handle on how do scaling in Lookout, and
captured several days worth of room temperature data.
Data ends on January 13th at 8:58 AM. The 'spike' at a little after 3
AM on the 13th was when I temporarily entered a bad scaling value. On
the 11th I dropped the thermostat by a degree at 3:49 PM, and the
resulting drop (from 73.4 degrees, right after the stoker had shut off)
to 71.1 degrees, a change of 2.3°, took 4 hours, and 15 minutes.
This is a rate of about 0.54° per hour at whatever outside
temperatures obtained at the time.
If I ever get around to building and setting up a trending system
for the stoker it would be interesting to get room temperatures from
several sources (right at the thermostat, as well as from other
locations) as well as the circulation water outlet and return pipes,
flue temperature (before and after the damper), recirculation loop
water temperature, stoker ambient temperature, and outside temperature.
Another useful sensor that wouldn't be a big deal to devise is a CdS or
solar cell based "light flux" detector so I can get a feel for how much
solar energy is available (sunny winter days yield less power cost),
and maybe even look for a cheap meterology setup that can report wind
speed and direction.
Main radiator loop
older pre-ITT B&G 'booster', model PAZ-3351 FX, part
225 PSI/250°F max. Pump motor is an equally
old B&G 1/10th HP, 1725 RPM, 1 PH., 60
Hz., 115 VAC,
1.9 FLA, serial # MOT102-5-9-M, and 'protector' MB558JV (the 2nd
and 3rd characters are partially missing, so may
incorrect). The FX is a date code (June 1980), and
(if the JV is as well) indicates Sept 1978.
Second radiator loop
Taco cartridge circulator, model
007-F4, 1/25 HP, 0.70 FLA, 3250 RPM, 115 VAC, 1 Ph., 60 Hz., 125
Main loop flow valve
Second loop flow valve
Taco #221, Universal Flochek, 1-1/2”
ITT/B&G model SA-3/4 C19, Part#
107022, 125 PSI/250°F max. “C19” date code is March 1991.
Pressure relief valve
ITT/B&G model FB-38 J09, P/N
110192, Set at 12 PSI, 125 PSI/225°F max. “J09” date code is
ITT/B&G model A-8 J09, P/N 110005,
Set at 30 PSI, 125 PSI/225°F max. “J09” date code is Sept
I think this is the original which was in the house
when purchased in the mid-60s. No nameplate is visible. The approximate
effective dimensions are
11-1/2” inner diameter x 35” long, so (V = Bh = pi r^2 h)
it has an approximately 3635 cubic inch (2.1 cubic foot)
Honeywell L8124A1007 triple 'Aqua-Stat'
controller. 120V 60 Hz., 0.2A thermostat current.
Installation Manuals (95-6571 and 60-0786)
Honeywell CT3400A1007 (mfg date code 9133) electronic thermostat. Obsolete.
Honeywell RA89A1074 switching relay, single-pole, single throw, 120V, 50-60Hz
transformer, 24V control circuit
Installation Manual (69-0790)
Honeywell - similar to the CT3400, but part # must be on the back, and
current generation units look nothing like it. I'm not bothering to
pull it off the wall; its only a freaking thermostat.
GE 5KC35MN43H, 1725 RPM, 1/3 HP,
115/230V, 6.0/3.0A, SF 1.00, FR56 frame, Code L
Martin 41BS10-5/8 sprocket on gearbox
output. 21 tooth sprocket on auger assembly side.
3-1/2” OD pulley on motor; 3” OD
pulley on gearbox. AP35 belt.
Motor and gearbox pulley sizes are
the same as were on the unit when we obtained it. However, the motor is
a slightly higher horsepower replacement (if memory serves, the
original was 1/4 HP) obtained when the first motor quit, and it didn't
have the same footprint, so needed to fabricate an adaptor plate, and
increase belt length.
linear inch of feed barrel
||Effective barrel fill depth
||Coal usage (linear inches)/hour
||Barrel capacity – pounds
||Barrel capacity –
effective runtime hours
||Estimated Effective BTU/Pound
||Estimated Effective BTU/Run Hour
||Equivalent Kilowatts/Run Hour
||Coal Cost/Run Hour
||Typical Electrical Cost/kWH
||Equivalent Electrical Cost/Run
||Typical Coal Usage/Year (Tons)
||Typical Run Hours/Year
||Equivalent Electrical Cost/Year
Taco Main Site
An excellent general reference source is the HeatingHelp.com site in general, and their library in particular.
Part 4 of the "Beacon Boiler Reference Book - Boilers between 1959 and
1972" contains specification data for Van Wert boilers, although my
specific model isn't on the list. My guess is the 'Economy Anthratherm'
VA13 model number is suggestive of a 13 pound per hour maximum
Other interesting material includes the Ipex "Manual of Modern
Hydronics", and the "How to Install Homart Hot-Water and Steam Heating
Created and maintained by Bob Welker for his own personal
trademarks, and so on that appear belong to their respective owners.
None of the
information contained within is guaranteed in any way.
Original work copyright 1999-2006 by Robert A. Welker.