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Further Experiments in Electrical

Electrical Heating Data Gathered from Eight Installations in Seattle (Wash.) Residences. For about four years the lighting de- heaters. No restriction was placed on partment of the city of Seattle, Wash., the time or amount of current used, has been investigating electric heating and the bills were paid by the owner for the home to see just what could be so that the tenant was free to use as done to make this form of heat cheap much current as he chose. Record of enough for general use.*

current was kept by recording meter, In the recently-issued biennial report and temperature (average, maximum of the Seattle Lighting Department, of and minimum), were recorded every which J. D. Ross is superintendent, an day for one year.

These records are account is given of progress of the in- in the department files. vestigation since 1913.

The consumption of current for the Since the electric heater, states the year was 12,360 kilowatt hours, and the report, of whatever type, transforms all maximum was 6,100 watts. Good ventithe energy supplied to it into heat, there lation was maintained, and the average is nothing to be gained by attempting to inside temperature was kept at 68° to raise the efficiency of the heaters them- 70° F. The recording meter showed selves. The problem is to generate and that the most current was used between distribute current at a lower price than 6:30 and 8:00 a. m. and 9:00 to 10:00 ever before, and then to utilize the heat p. m., with a considerable amount beso that the least amount will bring the tween 5:00 and 9:00 p. m. desired result, which is the maintenance The heaviest demand, then, comes at of a comfortable temperature with ample almost the same time as the lighting ventilation in the home.

peak. In order to make electric heatThe first side of the problem, that of ing load an off-peak load, some heat reducing the cost of current, may be storage is necessary. Electric heaters solved in Seattle, at least in part, by the adapt themselves to hot water, steam, development on a large scale of the hot air or direct heating or to any comwater power which is so abundant in bination of methods. this section of the country, and by the At 802 Thirty-third Avenue an elecdistribution of this power for heating tric water heater was installed to work by special heating circuits of higher volt- in conjunction with the boiler of the hot age than the lighting circuits and with

water heating system. In the coldest out the expensive voltage regulators weather both electric and coal heaters used on the lighting circuits.

were used ; in mild weather the electric

coil alone was used, and very often the DATA GATHERED FROM EIGHT INSTALLA-. coal heater alone was used. This arTIONS.

rangement gave excellent satisfaction in

heating the house, and the two heaters The other phase of the problem, the worked together without trouble. most economical use of the heat, has Another method of using electric heat been very clearly defined by the experi- as an auxiliary was tried at 516 Thirtieth ments carried on by the department Avenue South. The house had a hot during the past four years. Data have water heating system. The radiators in been gathered from eight different homes the rooms most used were equipped with equipped by the department for using individual electric heaters placed in the electric heat in every way that appeared basement directly under them. Each advantageous, both as an auxiliary and heater was connected so as to permit the as the sole method of heating.

water in its radiator to circulate through The first installation, at 1119 Grand it, and at the same time the circulation Avenue, was in small five-room cottage, from the coal-fired boiler was not interand consisted of open-air resistance fered with. No valves of any kind were

* A description of the original equipment, together with a report of the tests as made up to that time were published in THE HEATING AND VENTILATING MAGAZINE for January and March, 1915.

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DATA WHERE ELECTRICITY ALONE IS USED

FOR HEATING.

Experiments using electric heat as an auxiliary prove that it is most convenient, but give little information on the economy of using current alone.

Data on this point were gathered from four houses using electricity alone for heating. The first of these, on Thirtyseventh Avenue, was fully equipped with heaters, heat-storage tanks, circulation pump, automatic heat control, recording wattmeters and all the apparatus that was needed for a complete test. There were nine rooms, four on the first floor and five above. The downstairs rooms were kept at 70° F. during the day and allowed to run down to 60° F. during the night. The upstairs part was maintained at about 65° F. during the day. Heat control was entirely automatic;

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FIG. 1.

used. This arrangement is shown in the accompanying illustration. The hot water system can be operated entirely by electric current or by coal as desired, or only enough coal may be used to keep the entire house at about 60° F., and each electric heater may be used to bring its room to the temperature desired.

The first heaters used here were simply coils wound around a section of the pipe, using the pipe for a short-circuited secondary and getting the heating effect from the hysteresis and eddy currents in the iron pipe. These heaters were inferior to the resistance type used later on the same system in that their powerfactor was low and it was next to impossible to eliminate the humming sound. An induction-type heater has lately been developed that has a better power factor, and is so solidly constructed that it is practically noiseless.

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FIG. 2.

thermostats were used to keep the tem- entirely during the hours of lighting
perature within 2° of the desired mark, peak, amounting to 472 hours in the win-
and current was turned on in the morn- ter months. Readings were taken daily
ing by timeswitch so that the house for four months, beginning with Septem-
would be warm before time to arise. ber, 1914, of the average, maximum and

The installation was made in Febru- minimum air temperatures, inside, up-
ary, 1914, and the house has been main- stairs and downstairs. Readings were
tained at a comfortable temperature at also taken of the temperature of the cir-
all hours since, with practically no at- culating water, both outgoing and re-
tention. Characteristics of the house turning, to show the action of the storage
are as follows:

tank. This tank has proved able to care

First floor:

for the hours when the current is cut

Exposed wall area 2,492 sq. ft. off. The temperature at the end of the

Window area

180 sq. ft. 412 hours peak in December never drop-

Contents

.10,475 cu. ft. ped below 70° F. On the coldest days

Second floor:

the water in the tank dropped from 190°

Exposed wall area 2,357 sq. ft. to 104° F. during the peak, and the
Window area

197 sq. ft. usual range of temperature during cold

Contents

.12,275 cu. ft. weather was from 170° to 180° F. in the

Floor surface is included in the wall tank at the tiine the current was turned
area of the first floor to care for the off to 110° to 120° at the time it was
unheated basement. Three-fourths of turned on again. Readings on tempera-
the ceiling is included in the wall area tures have not been made regularly since
of the second floor.

the four months' test, but occasional
The house is of first-class frame con- checks show that the temperatures main-
struction. The hot water heating sys- tained inside the house are practically
tem is of liberal design, with a total the same as during the test. The table
of 690 sq. ft. of radiation. Four 101/2- on Page 31 shows the average tempera-
kilowatt bayonet-type heaters were used, tures and

current consumption by

arranged in parallel with a storage tank months.

of 500 gal. so that the water could circu- Three other houses were equipped

late from the radiator through the heat- with the same system of electric hot

ers or through the storage tank. Time water heat, and data collected for peri-

switch was used to disconnect the current ods covering approximately two years.

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K. W. H.

To Storage

Tank

Total

1,928

968

534

79

260

677

3,015
2,950

6,357

4,001 9,651

8,068

5,728

4,290

3,018

2,954

1,976

284

103

1.517
4,244
8,223
9,075
14,046
10,990
8,500
6,480

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66

Synopsis showing the current used per Sufficient data have been collected to year are given below. Characteristics enable the lighting department to make of each house are omitted; the square a definite statement as to what can be feet of radiation, which was figured on done in any given case. So many varithe same basis as that in the Thirty- able factors enter into the heating of a seventh Avenue house, is given in each home that each house must be studied case, and serves as a measure of the and estimated by itself. The problems estimated heat requirements.

presented are almost entirely the same

Address

225 37th N. 1505 36th Number of rooms

9

9 Kilowatt heaters

42

32 Square feet radiation

690

640 Consumption, first year, K.W.H.

42,850 39,320 Consumption, second year, K.W.H.

63,860 41,880 Average consumption, K.W.H.

53,355 40,600 Consumption per square foot of radiation per year, K.W.H.

77.3

63.4 * U'sed as auxiliary only during second year.

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EXPERIMENTS WITH OIL-FILLED that have been met with regularly in RADIATORS.

heating and ventilating, except that we

have kilowatt hours to deal with instead During 1915 a number of heating in- of British thermal units. With electric stallations were made with oil-filled, elec- heat the energy is, in general, several tric-heated radiators. These consist of times as expensive as in the form of an ordinary hot-water radiator filled with coal, so that every device for saving heat oil and having a cartridge-type heater is valuable. inserted in the top.

This scheme of

In the ordinary building with good heating has the advantage that each

ventilation the heat loss is about fourroom has its own heater, and no piping fifths through the walls, while one-fifth is necessary. The radiator in each room

is used to heat the air. With improved may be turned off when not needed, al

heat insulation in buildings it is conthough nothing is to be gained by turn

ceivable that half the heat now required ing off the heat where a comfortable

may do the same work, without in any temperature is to be maintained for most of the day, because more heat will be

way impairing ventilation, which re

quires about 30 cu. ft. per minute for needed to warm the room again than was

each person. Any improvement tending saved while it was cooling. Results ob

to reduce the amount of heat necessary tained with the oil radiators are the same in current required and tempera

gives an advantage to electricity as comtures maintained as with the hot water

pared with lower priced sources of heat. system, with the exception that there The hot water heating system, with is very little storage of heat in the oil ample storage tank, seems to present radiators to tide over the time when the most advantages for use with eleccurrent is turned off.

tric heaters. This is due to the fact that Data on two houses with this system the heat storage keeps a uniform temfollow at bottom of page.

perature, for less heat is required for

Address
Number of rooms
Kilowatt heaters
Square feet radiation
Duration of test-months
Consumption, kilowatt hours
Estimate for one year, K.W.H.
Estimate per square foot radiation, K.W. H....

2541 11th Ave. W. 1238 E. Fir

5 1072

3112 160

640 7

7 9.777

50,960 16.000

85,000 100

134

ughly five

as

a

comfort with steady than with intermit- theory, which

theory, which says that the 10,000 tent heat.

B.T.U. in a pound of coal cost 0.3 cents, The tank, fitted with a small centrif- while in the form of current, the 3,413 ugal circulating pump, will keep the B.T.U. in one kilowatt hour will cost house at an even temperature during 12 cent, making the current the lighting peak when the current is times as expensive. Then allowing for a shut off. Heating, however, cannot be furnace efficiency of 40%, which is fair permanently classed an off-peak

- for the ordinary furnace, the current load. This is evident from the fact that would prove twice as expensive. The about ten times the capacity of installa- showing of less than one and one-half tion is necessary for heating a house times made in the experiments is probthat is used for lighting it. When one ably due to more care in the use of the house in ten is electrically-heated, then heat so that less was wasted. the load curve valleys will be filled up.

ADVANTAGES OF ELECTRIC HEAT. After that the success of heating by electricity demands cheap current at all It is very noticeable that once electric times, which is only to be had from water heat is installed in a home the occupants power, generated in large units and dis- do not like to consider its removal. It tributed at comparatively high voltages. delivers the home from the drudgery of It may be feasible to serve heating cus- building fires and handling coal and tomers at 400 to 500 volts three wire, ashes, and banishes the disagreeable and which would materially reduce distribu- injurious extremes of temperature so tion cost.

often tolerated now. It generates no

poisonous gases and does not vitiate the ANALYSIS OF ELECTRIC HEATING COSTS. air. It is, indeed, the ideal heat in

everything save expense. The advanThe comparative cost of this method tages of its use are sure to overbalance of heating is fairly well established. It the additional expense involved for a is from 25% to 50% more expensive for great class of people who demand the electricity at 72 cent per kilowatt hour best and are able and willing to pay for than for coal at $6.00 per ton. At 1 it, so that electric heat is certainly descent per kilowatt hour the electricity is tined for a great development, even two and one-half or three times as cost- though it may never replace the more ly. These figures are borne out by familiar forms now used.

Priming in a Heating Boiler

By H. S.

A large percentage of trouble in low Where this is done, it is usually advispressure steam heating systems is caused able to wash out the wet returns in the by the priming of the boiler. Many same manner. steam fitters simply blow off the boiler Almost every heating boiler, particuunder pressure and endeavor to cure the larly those which have been installed trouble in that way. In most cases this for a period of time, has an accumulamethod is inadequate, as any grease or tion of sediment, mud, scale and other oil on the surface of the water will cling foreign matter lying at the bottom. It to the sides of the boiler as the water is is difficult, in most cases, to get access being blown out through the blow-off to that part of the boiler in order for valve. It is also surprising the number cleaning purposes, especially in the case of fitters and boiler men who use soda of sectional cast-iron boilers having a in eliminating the foreign matter from water leg on each side. Foreign matthe boiler. The soda is placed in the ' ter will collect at the bottom of these legs. boiler through the safety valve connec- and, if not removed, will eventually tion and boiled up for a time. The water cause a cracked section. Not only that, is then blown out by means of a hose. but foreign matter is the chief cause of

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