US1813891A

US1813891A - Reenforced circulating coil

Info

Publication number: US1813891A
Application number: US257222A
Authority: US
Inventors: Friedman Arthur
Original assignee: Cleveland Heater Co
Current assignee: Cleveland Heater Co
Priority date: 1928-02-27
Filing date: 1928-02-27
Publication date: 1931-07-07
Anticipated expiration: 1948-07-07

Description

July 7, 1931. A. FRIEDMAN 1,813,891

REENFORCED 'CIRCULATING COIL Filed Feb. -27. 1928 Patented July 7, 1931 ,UNITED STATES PATENT OFFICE ARTH'UR FRIEDMAN, OF CLEVELAND, OHIG, ASSIGNOR TO THE CLEVELAND HEAT-ER 1 COMPANY, OI CLEVELAND, OHIO, A CORPORATION OF OHIQ i REENI'ORCED GIRGULATING COIL Application flled lebruary 27, 1928. Serial 1T0. 257,222.

This invention relates to improvements in gas burning liquid heaters and in particular to the circulating coils used in gas burning domestic water heaters. I 7

It has for its object the provision of a water heating circulating coil that is inexpensive and easy to manufacture, and that is more 1 durable than the ordinary type of circulating coil, and that is re-enforced and protected against the destructive action of the condensation formed thereon from the productsof combustion of the gaseous fuels commonly used in gas burning water heaters.

My invention in general consists in the provision of adouble section of tubing which constitutes'that portion of the heater coil terminating inthelower coil coupling. This l e-enforcement in general extends about three or four inches from the coupling and is placed 'three for the purpose of strengthening the recoil, at this point, against the corrosive action ofthe liquids which condense on the heater coils and eventually find their way to the lowest portion ofthe heater coils collectingat the junction of the coils and the coupling. 1 Y In copper heater coils of the, ordinary type there is a decided tendency for the coils to fail at the point where they enter the lower Coupling member. This failure of the coils is due to the disintegration of the copper from which thecoils are made, and is usually accompanied by the formation of copper. sulphate or other decomposition compounds at the point offailure at the coil. It is common knowledge that many commercial gases, particularly manufactured gas, upon burning give off an oxide of sulphur as well as water vapor, 7

he accepted theory ofthis phenomena observed in gas fired water heaters is that the condensation of watervapor which takes place on the heater coils, causes the formation of .ik sulphurous acid by combining with the sul- :phur dioxide/given oil by the'burning gas.

As the weak sulph'urous acid thus formed on the heater coils runs to the bottom of the coils, a certain amount of it is converted into sulphuric acid, by reason of coming in contact with what copper oxide may be present on the heatercoils.

The dilute acids thus formed collect at the lowermost point of the coils, which is where they enter the bottom coil coupling. At this point there is apt to be present considerable copper oxide if it is a brazed joint. oxide referred to is present as a result of the action of the gas flame used in the brazing operation. f

Furthermore, the copper tubing at the brazed joint is somewhat weakened, due to the heat applied in brazing, which causes some oxidation as well as annealing, both of which are apt to leave this portion of thejoint between the tubing and the coupling,

whether it be a brazed joint or a union coupling, it is apparent that a part of the aforementioned liquids, condensed from'the products of combustion of the gaseous fuel, come to rest at the junction of the coupling and the coils. I

At this junction point, which is in close proximity to the heater burner, the condensation products are further concentrated by direct action of the flame and evaporation of excess water in the acid solutions producing concentrated sulphuric acid, which readily combines with the copper of the heater coil.

It is upon thistheory, which is supported by the presence of copper sulphate at the The lower extremities with a short r-e-enforcing interior of the heater coils accelerates their deterioration. Under these conditions, when in operation, the heater coils are kept at a much higher degree of temperature, due to the low thermal conductivity of the fouled tubing, and in addition to being more rapidly disintegrated by sulphuric acid, the coils are also oxidized by the direct action of the burner flame.

The primary object of this invention is to re-enforce that part of the heater coil which is most apt to be attacked by the aforementioned condensation products of combustion.

This result is accomplished in my improved coil by the provision of anextra section of tubing over the last few inches of the lower portion of the coils. By this arrangement the coil is materially strengthened at this point and its useful life should be materially lengthened thereby.

This invention is particularly useful in water heaters in which the ends of the circulating coil are brazed in the coil coupling member, as the coils are somewhat weakened by this operation, due to the high heat which "is applied to them, and to the action of the fluxes which are used in brazing.

In the accompanying drawings Fig. 1 shows a front elevation, partly in section, of a water heater constructed in accordance with, and adapted for use in practising my invention. Fig. 2 is a plan elevational view partly in section of the coil coupling and the coil re-enforcing member.

Referring to the drawings, the reference numeral 1, indicates the heater casing or jacket of a conventional gas fired domestic water heater. This casing provides a housing for the copper circulating coils 2 which are adapted to be put into communication with a storage vessel or tank by means of the low-er and upper union-

connections

3 and 4, respectively. 7

Means for applying heat to the coils is provided for by the gas burner 5, which'is mounted on an air and gas mixing tube 7,

of the Venturi type. Theburner 5 is positioned below the coils in the lowerportion of the heater jacket. A gas cook 8 is mounted at the inlet end of the mixing tube 7, and is adapted to be connected to a source of gas supply.

he heater coils 2 are provided at their section 9, of tubing which is adapted to be secured in the couplingmember 6 by any suitable method such as brazing. The joint 10 between the overlapping re-enforcing section and'the coil to which it is applied may also be effected by brazing. i

The ire-enforcing sections 9 may be formed independently of the coils 2 and then slipped over the coils before the brazing operation, or theymaybe formed by the same operation that is used in forming coils 2. The sections 9, if so desired, may be made of heavier gauge tubing than the coils 2. The coils 2 may be made to terminate a short distance from the joint 10 instead of extending to the end of the re-enforcing sections 9. As shown in the drawings, the joint 10 of the

coil sections

2 and 9 joins these portions of the coil to each other with a smoothly bevelled joint so that there will be no tendency for the collection of condensate at this point.

It is apparent from the foregoing that this type of re-enforcement will materially lengthen the life of the coils and protect them against sulphation, as well as, oxidation by the flame of the burner 5, which is apt to happen in casethe interior of the coils becomes covered with scale.

It is apparent that my improved heater coil could be used in conjunction with oil burning water heaters as well as gas burning Having described my invention, I claim:

: 1. In a water heater, a vertically arranged tubular circulating coil, a coupling member for the lower end of said coil, heating means located below said coil, and coil re-enforcing means comprising a relatively short'section of tubing providing a protective. sheath that encompasses the lower end portion of said coil to protect said coil. at the point where it enters said coupling fromthe corrosiveaction of condensate deposited on said coil and collected at this point.

2. In aliquid heater, a vertically arranged tubular circulating coil, means for supply ing heat to said coil, a relatively short re-enforcing sleeve positioned on the lower end portion-of said coil to protect the same against the corrosive action of condensate collected on the coil at this point, and a coupling member'connected in fluid tight relation to the end portion of said sleeve and coil.

3. In a'liquid heater, a vertically arranged tubular circulating coil terminating in a double walled portion of less than 40i a coil turn at its lower extremity, means for supplying heat to said coil, and a coupling member brazed to the lower end of said coil,

said double walled portion of the coil being adapted to strengthen the coil against the corrosive action of condensate collected at the junction of said coupling and coil.

4. In a liquid heater, means for supplying heat thereto, a vertically arranged tubular circulating coil formed from a piece of metal tubing, at protecting sleeve formed from a relatively short section of tubing of similar material and of larger diameter than the coil tubin fitted over the lower end portion of the tufiing of said coil, and a coupling member receiving and brazed to the end of said coil and sleeve, said sleeve strengthening the junction of said coupling and coil.

In testimony whereof I afiix my signature.

ARTHUR FRIEDMAN.