Improvements in Bakers' Ovens Set with External Heating Flues.
Year: 1890

page_text: Date of Application, 3rd Nov., 1890
Complete Specification Left, 29th Aug., 1891-Accepted, 3rd Oct.. 1891
PROVISIONAL SPECIFICATION.
Improvements in Bakers' Ovens Set with External Heating Flues.
We, OLIVER EDGAR MCGREGOR, of Queens Square, Wolverhampton in the
County of Stafford, Baker and Confectioner, and JAMES MILLS, of 166
Wednesbury Road, Walsall in the said county, Foreman Pastry Cook and
Confectioner, do hereby declare the nature of this invention to be as follows:-
Bakers' ovens are usually required to be at a somewhat high temperature early
in the day, for a short time, for cooking fancy descriptions of pastry, and the
temperature requires to be considerably reduced for ordinary use.
When an oven is set with externally heated flues, and heated entirely by external
heat, a considerable quantity of fuel is required to raise the temperature of the
flues and brickwork sufficiently to produce the required degree of temperature
within the oven for cooking fancy descriptions of pastry, and the reduction in the
temperature of the oven necessary for ordinary cooking is not conveniently effected
as quickly as is desirable, and can in any case be effected only by a considerable
waste of the heat which has previously been imparted to the flues and brickwork
surrounding the oven.
Now, this invention has for its object means whereby bakers ovens, set with
external flues, may be raised to a high temperature for the purpose of cooking
fancy descriptions of pastry without it being necessary to heat the surrounding
flues and brickwork beyond the temperature required in ordinary cooking.
According to this invention, a bakers oven set with external flues is "flashed,"
to raise it to the necessary temperature for cooking fancy descriptions of pastry,
by passing the products of combustion through it. For this purpose an opening
controlled by a damper or valve is formed in the back of the oven, and an outlet
controlled by a damper at the front of the oven communicates with a flue passing
to the chimney. Both these dampers are opened when it is desired to flash or raise
the oven to a high temperature, and the products of combustion pass from the flue
at the back of the oven through the opening in the back of the oven, thence through
the interior of the oven and out through the outlet opening at the front thereof.
When the temperature has been sufficiently raised in this manner, the dampers arc
closed and the pastry is placed within the oven and cooked. The dampers remain
closed when the oven is used for ordinary cooking, and thus it will be seen that,
according to this invention, no (or but little) reduction in the temperature of the
flues and surrounding brickwork is necessary to adapt the oven for ordinary cooking.
In the case of ovens set with a sulphur ventilator or flue at the front. such flue
may be utilized as the outlet flue also for the products of combustion which pass
through the oven.
Dated this 1st day of November 1890.
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in Bakers' Ovens Set with External Heating Flues.
We, OLIVER EDGAR MCGREGOR, of Queen's Square, Wolverhampton in the
County of Stafford, Baker and Confectioner, and JAMES MILLS; of 2 Brunswick
Terrace, Wednesbury Road, Pleck (formerly of 166 Wednesbury Road), Walsall
in the said county, Foreman Pastry Cook and Confectioner, do hereby declare the
nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :--
Bakers ovens are usually required to be at a somewhat high temperature carly
in the day, for a short time, for cooking fancy descriptions of pastry, and also
(when used for baking bread) from time to time during the day previously to
inserting fresh batches of bread, and the temperature requires to be considerably
reduced for ordinary use.
When an oven is set with external heating flues, and heated entirely by external
heat, a considerable quantity of fuel is required to raise the temperature of the
flues and brickwork sufficiently to produce the required degree of temperature
within the oven for cooking fancy descriptions of pastry, or for commencing to
bake a batch of bread, and the reduction in the temperature of the oven necessary
for ordinary cooking is not conveniently effected as quickly as is desirable, and can
in any case be effected only by a considerable waste of the heat which has previously
Bakers' ovens
been imparted to the flues and brickwork surrounding the oven.
have been set with furnaces for heating the external heating flues and with separate
furnaces for flashing" them by passing the products of combustion therefrom
through the ovens, but this involves a wasteful expenditure of fuel as will be
obvious, besides being otherwise inconvenient.
6:
Now, this invention has for its object means whereby bakers' ovens, set with
external heating flues, by means of which they are heated as continuous ovens, may
be raised to a high temperature for the purpose of cooking fancy descriptions of
pastry, or commencing to bake batches of bread, without the use of a separate
furnace for "flashing" and without it being necessary to heat the surrounding
flues and brickwork beyond the temperature required in ordinary cooking; the
invention is useful, however, in getting up the temperature quickly when such is
required either for the purpose above specified or other purpose.
According to this invention, a bakers' oven set with external heating Anes is
"flashed" to raise it to the necessary temperature for cooking fancy descriptions
of pastry, or for commencing to bake a batch of bread, by passing products of
combustion through it from the furnace which is used to heat such flues. For this
purpose, a flue from the furnace has an opening therefrom into the oven controlled
by a damper or valve, and an outlet, controlled by a damper, at the opposite end
or side of the oven communicates with a flue passing to the chimney. Both these
or raise the oven to a high
dampers are opened when it is desired to flash
temperature, and products of combustion pass out of the flue above described
through the opening therefrom into the oven, thence through the interior of the
When the temperature has
oven and out through the outlet opening therefrom.
been sufficiently raised in this manner, the dampers are closed and the pastry o
bread is placed within the oven and cooked. The dampers remain closed when the
oven is used for ordinary cooking, and thus it will be seen that, according to thi
invention no (or but little) reduction in the temperature of the flues and surrounding
brickwork is necessary to adapt the oven for ordinary cooking. In the case o
ovens set with a sulphur ventilator or flue at the front, such flue may be utilize
as the outlet flue also for the products of combustion which pass through the oven
A convenient means of carrying this invention into practice is shewn by th
drawings herewith, which illustrate it as applied to a range of two ovens one abov
the other.

page_text: Figure 1 is a front elevation of the ovens,
Figure 2 a back elevation thereof,
Figure 3 a longitudinal section taken on line ar a of Figure 4, the left hand end
of this view being a section taken on line y y of Figure 2, so as to shew both the
Hue A. hereinafter described and the furnace;
Figure 4 is a sectional plan taken on line of Figure 3, and
Figure 5 is a sectional plan taken on line of Figure 3.
From the furnace B which heats the external heating flues, a flue A passes up at
the back of each oven C, and from this flue an opening a is formed, respectively,
into the back of each oven C, the flue being blind except for these openings, that
is to say it has no other outlet by which to communicate with the chimney. This
fiue and the openings therefrom are shewn by full lines in Figures 3 and 4, but by
broken lines only in Figure 2. It is shewn to be somewhat out of the centre of
the ovens to clear the openings m m which are used for cleaning out the flues n n²
which pass over the roofs of the ovens. If the openings mm are placed out of
the centre, the flue A may of course be central. Each opening a from the flue A.
is fitted with a damper which may be opened and closed by the aid of a lever c
carried in lugs on a plate o. The outer end of each lever e passes through a slot d
formed through the thickness of the outer wall D, and through a slotted plate e.
The plate o closes the inner end of the slot d, an opening being formed through
A face view of one of the plates e is
such plate for the passage of the lever.
shown by Figure 6, in which el is the slot through the plate for the passage of the
lever, and are notches into any of which the lever may be caught sideways and
held in its desired position. The plates o and e are fixed to the brickwork by
bolts passing through holes in the plates e and through corresponding holes in
the plates o: Dampers are fitted to the flue A, the lower one for shutting off the
communication thereto from the furnace, and the upper one for shutting off the
upper part of the flue, that is the part which passes up at the back of the upper
oven, from the furnace; and air bricks y are provided in the wall D by which, or
the upper of which, cold air may be let into the flue A, or into the upper portion
thereof, to reduce the temperature therein when such flue, or the upper portion
thereof as the case may be, is cut off from communication with the furnace B.
An opening in the roof of each oven and at the front end thereof, as shewn,
communicates with a fluci which itself communicates with the chimney. Each
Hlue is shewn in the illustrations to lead into a vertical fluej which leads into a
The flues i
main vertical flue and communicates therethrough to the chimney.
are shewn by full lines in Figures 3 and 4, and by broken lines only in Figure 1.
Each opening into a flue i fitted with a damper 7 by which it may be closed.
or partially closed, as desired.
When it is desired to "flash" the ovens, for the purpose above described, the
dampers and are opened, and products of combustion pass from the furnace B
up through the flue A, thence through the openings a into the interior of the
ovens and out therefrom through the openings h, flues i, flue j, and thence
through the flue & into the chimney. When the temperature of the ovens has been
sufficiently raised in this manner, the dampers are closed and the pastry or bread.
When the ovens are used for ordinary
is placed within the ovens and cooked.
cooking, the dampers are kept closed; and if it is desired to reduce the temperature
of the brickwork surrounding the flue A the air bricks g may be opened to allow a
current of air to pass through the flue for such purpose. The chief purpose,
however, of letting in the current of cold air when such is needed, is to cool the
dampers, as being of metal they are of course rapid conductors of heat. The
flue A being very short and cut off from the other or external heating flues,
the cooling it down in the manner described causes but a very slight loss of heat,
as will be obvious: If the lower oven only is to be "flashed" the upper
dampers and are closed and the lower ones opened. The upper oven only
may be flashed," if desired, by opening both the dampers f and the upper
dampersand, but in such case the portion of the flue A which passes at the

page_text: back of the lower oven cannot be cooled by a current of air. A separate flue A
may, however, be carried up at the back of each oven, if desired, and fitted with a
damper and air brick so that either of the ovens can be "flashed" independently
of the other, and the flue at the back of the other be cooled at the same time by a
current of air. The openings h and flues i may be used also as sulphur ventilators
if desired; or, in the case of ovens provided with sulphur ventilators, such may be
used for the purpose of carrying off to the chimney the products of combustion
entering the ovens through the openings a for the purpose described.
The external heating flues may be cut off from the chimney by means of a
damper to bottle up the heat therein while the interior of the oven is being heated
by the gases passing therethrough.
The invention is obviously applicable to a single oven, or to any number set
together, its application to a set of two being given simply by way of example.
The ovens, apart from the special features described as constituting this invention,
may be constructed and set in the usual or any convenient manner in which
externally heated ovens are set. According to the setting and means of externally
heating illustrated by the drawings herewith, and in respect of which no claim is
made, the licated gases from the furnace B pass through a number of openings
into side spaces r, which are open to the whole of the underside of the bottom of
the lower oven being joined across by the flue or spaces between the top of the
furnace B and combustion chamber and the underside of the bottom of the oven;
and the gases pass also from the combustion chamber tout at the end thereof into
the side spaces and flues. The gases pass from under the bottom of the lower
oven into upward flues at the front (see Figures 1 and 5), and from thence pass
into the flue between the upper and lower ovens, and again from thence through
upward flues at the back (see Figures 2 and 4) into the flue which passes over
the top of the upper oven; and the gases pass finally to the chimney through the
flue (shewn by broken lines only Figure 1) at the front.
The arrangement described for flashing" the ovens may be used also in
addition to the external heating flues in getting up the temperature quickly when
such is required.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what
we claim is —
1. Bakers ovens (or a single bakers' oven), set with flues by which they are externally
heated as continuous ovens, provided with means, substantially as described, by
which they may be "flashed," or the temperature raised more quickly than by the
external heating flues only, by passing products of combustion through them from
the furnace which heats such flues, and such products be cut off from the ovens
when desired, for the purpose set forth.
2. Bakers' ovens (or a single baker's oven), set with flues by which they are
externally heated as continuous ovens, having a flue passing at or near the back of
each oven, from the furnace which heats the flues for external heating, and each
oven having an opening thereinto from such flue controlled by a damper, with an
opening out therefrom, at or near the front end, controlled by a damper and
communicating with a flue which leads to the chimney, all substantially as described,
and shewn by the drawings herewith, for the purpose set forth.
Dated this 27th day of August 1901
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicants.