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NATIONAL BUREAU OF STANDARDS REPORT

3993

PERFORMANCE OF A GAS-FIRED WALL HEATER

INSTALLED IN A BASEMENTLESS HOUSE

by

Oo No McDorman

Po Ro Achenbach

Report to

Federal Housing Administration

Washington, Do Co

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
U. S. DEPARTMENT OF COMMERCE

Sinclair Weeks, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director

THE NATIONAL BUREAU OF STANDARDS

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NATIONAL BUREAU OF STANOAHOS REPORT

ms s»ROj£CT ms mpom

1003-30-4^30 March 22, 1955 3993

PERFORMANCE OF A GAS-FIRED WALL HEATER

INSTALLED IN A BASEMENTLESS HOUSE

by

Oo No McDorraan

Po Ro Achenbach

Heating and Air Conditioning Section

Building Technology DiTision

to

Federal Housing Administration

Washington, Do Co

<^BS>

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The publication, roprini unloM permission Is obti 25,O.C. Suehpermisa

tally prepared If that i

* 11* 1 i,.! art, Is prohibiteo Approved tor public release by the

,

. . irds, Washington Director ot the National Institute of , , ,, has been speclh* Standards and Technology (NIST)

on October 9, 201 5.
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PERFORMANCE OF A GAS-FIRED WALL HEATER INSTALLED

IN A BASEMENTLESS HOUSE

by

Oo N. McDorman and ?„ R., Achenbach

ABSTRACT

A study was made of the performance of a gas-fired

wall heater in a house without a basement with gravity circulation of air through the unit and with a

booster fan to increase the air circulation. The results revealed that the heat loss of the structure

was not significantly greater than for other heating

methods wherein the heating unit is incorporated entirely in the heated space and that the heat loss

could be calculated by conventional methods although

the uncertainty in the rate of infiltration might result in inaccuracies in some cases. It was shown

that insulation was desirable over the ceiling to restrict heat loss upward and also to promote radiation

downward from the warm ceiling surface. Wall heaters

without ducts employing gravity circulation or a

booster fan are likely to produce significant temperature differences between rooms, between different

levels in the same room, and between stations at the

same level within rooms. These temperature differences were observed to be of such magnitude as to

suggest limitations on the size of house, severity of

climate, heat loss of the house and number of doorways between the heater and any heated room that

could be associated satisfactorily with this type of

heat distribution. The test results indicated that

no more than one average-size doorway should be interposed between the heater and any room to be heated;

a limiting distance of iS feet, as presently specified in FHA Minimum Property Requirement, is probably

too great for all applications; and design winter

temperature of 0®F should be a lower limit for this

type heating system unless the heat loss of the house

in question can be reduced appreciably below 50 Btu/hr

per sq ft of floor area at design outdoor conditions,

1. Introduction

At the reouest of the Federal Housing Administration in a

letter dated August 16, 1954 a study was made of the performance

of a typical gas-fired wall heater with gravity circulation

of air through the unit and with a booster fan to augment the

air circulation within the furnace housing. A wall heater

manufactured by Royal Jet Inc. of Alhambra, California was

used for this investigation. With gravity circulation the

heater was designated as the manufacturer’s model FG-3-45

whereas the model number was FF-3-45 when the booster fan

was attached to the same heater.

The purpose of this investigation was to study the

temperature distribution produced in the Test Bungalow by

a wall heater with and without the booster fan with respect

to horizontal and vertical temperature gradients as a basis

for judging the acceptability of this type heating system

for various climates and various sized houses. The observed

heat loss of the house was also compared with the heat loss

computed by the method described in the Guide of the American Society of Heating and Air Conditioning Engineers to determine whether a gravity warm air furnace should be penalized

in capacity when located on the living level of a one-story

house.

The noise level produced by the quipment was also observed in the various rooms of the Test Bungalow.

II . Description of the Heater

The Royal Jet Heater employed a raised port burner ignited

by a pilot, and a dimpled heat exchanger. The unit was designed for vertical installation within the living area as a

gravity heater without discharge ducts. The specimen was

rated at 45*000 Btu/hr input and 31*500 Btu/hr output. The

casing measured overall 93-inches high, 3/4-inches wide and

14~inches deep. Three views of the heater installation in the

Test Bungalow are shown in Figs. 1, 2, and 3» Fig- 1 shows

the heater as seen from the kitchen, Fig. 2 as seen from the

living room and Fig. 3 as seen from the hall. Fig. 4 shows

the location of the heater on a floor plan of the house and

indicates the location of the supply and return grilles.

The inner liner of the unit could be fitted with different heads to deliver warm air in two, three, or four directions

as required by the particular installation. A head that delivered warm air to the living room and hall only was used for

some of the tests whereas a head that delivered warm air to

the living room, hall, and kitchen was used for the remainder

of the tests. The dimensions of the openings in the heads and

the supply and return grilles are summarized below.

Openings in Supply Return

Room Head, In. Grilles, In. Grilles, In.

Kitchen

Living Room

Hall

19 3/4x7 26 1/4x11 3/4

7x6 11 3/4x9 5/^

7x6 11 3/4x9 5/^ 11 3/4x9 5/S

26 1/4x11 3/4

11 3/4x9 5/S

The booster fan used with the heater carried the following

name plate data.

Model 3300, Volts 115? eye 60, Ser 4Y, Type L, Amp 0.30,

RPM 1570, Redmond, Oivosso, Michigan, High Impedance Protected,

A App. No. 5319 o The booster fan consisted of two squirrel cage

motors mounted on the two ends of the blower motor. The blowers were arranged for free discharge of air vertically upward

through the heater.

The thermostat used for some of the tests was a wall thermostat manufactured by General Controls Company employing a

thermoelectric circuit for actuation of the control,

III , Test Equipment and Procedure

The Test Bungalow remained in the same condition with

respect to insulation and construction features, as for other

heating systems recently tested. Significant factors were as

follows: plastered ceiling, fluorescent illumination, weatherstripped windows and doors, uninsulated outside walls, basement ceiling consisted of 1-inch rigid insulation board nailed

directly to the under side of the floor joists. The ceiling

was insulated from the attic space with two layers of commercial "double thick" rock wool. The effective thickness was

determined to be 5<.4 inches. The Test Bungalow was operated

as a basementless house for these tests even though it had a

full basement. The basement temperature was controlled for

similar tests to provide comparative data.

The temperature distribution was ascertained by means of

200 thermocouples enclosed in 3-inch cork spheres located at

five stations and five levels in each of the four large rooms

and three stations and five levels in the bath and at other

suitable stations on the floor, embedded in the ceiling surface, on the sidewalls, and in basement, attic and out-ofdoors. Additional thermocouples, of the parallel multiplejunction type were placed at the heater inlets and outlets.

The temperature of the gas supply was measured by means of

a thermocouple inserted in the gas stream.

The absolute values of the heat transmitted to the attic

were determined with the aid of twenty heat flow meters placed

over the first layer of rock wool insulation in the attic.

After steady state conditions had been maintained in outside and inside temperatures for approxiately S hours, test

periods of about 12 hours commenced, during which observations

of the inside temperatures for approximately 150 stations were

recorded at 4~hour intervals. Hourly recordings were made

of the following temperatures: outside air, 30-inch level at

five room centers, 5 positions in basement, 5 locations on

furnace, gas supply temperature, and the closet. The accuracy

of the measuring circuit was checked hourly using melting ice

as a standard. Gas consumption, electrical energy used for

lighting the house, electrical energy consumed by fan motors,

and gas pressure were recorded hourly.

An auxiliary desk-type fan was used to direct air from

the hallway toward the two bedrooms during one test for comparison with similar tests using gravity circulation or the

booster fan,

IV Test Results

The temperature distributions observed in the Test Bungalow during nine tests under steadv state conditions are summarized in tables 1-9 inclusive. Table 10 summarizes the performance of the heater, the heat loss of the house, and some of

the more significant temperatures in the structure. The tests

were made at outdoor temperatures ranging from to -15°Fo

Some of the tests were made with gravity circulation of the air

whereas the booster fan was used for others and an auxiliary

desk-type fan was used for air circulation during test 3, Two

supply and return grilles were used for a part of the tests

whereas three were used for other tests. Test 4 was made with

a higher basement temperature than the other tests with the

same outdoor temperature. These variations in test conditions

are shown in tables 1-10, Table 11 summarizes the results of

the noise measurements made in the house.

Temperatu re Pi stri bution

The av- ' oT the te,-;perabures observed at five Jeyels j of the f Iv-v ••• <-'f a’i- •oijre ..-''mmarl zed nr tables 1-9.

The station at the cea'.or of the livinp- room 30- in dies above

the floor was used as a control point for the tests o In test

1 with an outdoor temperature of about -15°F the Royal heater

was able to maintain a temperature of 70o6°F at the control

point when operating continuously with gravity circulation

of the air through the heater. The average of the temperatures at all stations at the 30 -inch level in the living

room was 6^,^°F and the average of the temperatures at the

same level in the four other rooms was 6o6°F lower than the

living room average. Table 2 shows that the average of the

temperatures observed at the 30-inch level in the living room

was raised to 70<,S°F when the booster fan was employed at the

same outdoor temperature, and the average of the temperature

at the same level in the other four rooms was 5o4*^F lower

than the living room average. Table 3 shows that the auxiliary fan raised the average temperature at the 30-inch level

nn the two bedrooms above 70®F and also raised the temperature at the same level in the kitchen and bath to near 70°F.

When the outdoor temperature was maintained at about

-5°F, as for the tests summarized in tables 5-7j average

temperatures above 70°F were produced in the kitchen and

living room at the 30 -inch level with gravity circulation

of the air and the other three room averaged 6S,2°F at the

same level. When the booster fan was used for circulation

of air the average temperatures at the 30-inch level in all

rooms were above 70°F with either two or three supply and

return grilles on the heater as shown in tables 6 and 7.

These two tables show that the principal effects of using

a third supply and return grille in the kntchen were to

increase the temperatures at all levels in the kitchen and

to reduce the temperatures at all levels in the other rooms.

Tables ^ and 9 show that the living room temperature

at the 30-inch level averaged 4o0°F higher at an outdoor

temperature of 15°F and 3,1°F higher at an outdoor temperature of 31°F than the corresponding average of the other

four rooms respectively.

Tables 1-9 show that there was less variation in average temperature between rooms at the 30-inch level than at

any other level of observation.
i
Vertical Temperature Differences

The test results show that the temperature difference

in the living zone from 2 to 60 inches above the floor ranged

from 7o7°F for an outdoor temperature of 32°F to 16„6®F for

an outdoor temperature of -15°F with gravity circulation of

air through the heatero The 2 to 94-inch temperature difference ranged from l^o°F to 3^oO°F for the same range of outdoor temperature

o

The effect of using the booster fan or an auxiliary 16-

inch non-oscillating desk-type fan placed in the hall near

the warm air outlet is shown in Fig„5 and in Tables 1-3 inclusive o The booster fan raised the temperature from 2 to 5

degrees at all levels in the house but had no beneficial

effect on the temperature differences between levels o The

booster fan raised the temperature of the floor surface at room

centers 5o2°Fo The auxiliary fan raised the room temperatures

below the 50-inch level and decreased the temperatures above

the 65-inch level thus reducing the temperature difference between levels as compared to gravity circulation or booster-fan

circulation of the air in the houseo As shown in Fig» 5 and

table 3 the vertical temperature difference between the 2 and

60-inch levels was llo3°F whereas that between the 2 and 94-

inch levels was 20o^°F for an outdoor temperature of -13°F when

the auxiliary fan was used for air circulation«

Figo 5 shows that the air 2-inches below the ceiling

averaged about 10°F warmer than the ceiling surface at room

centers for gravity and booster fan circulation of the air

whereas this difference was about 7°F when the auxiliary fan

was in operation « A temperature difference of only about

1 l/2°F would be required between air and ceiling surface to

transfer all of the heat lost through the ceiling to the attic.

This indicates that the major portion of the heat transferred

to the ceiling by convection was radiated downward to the walls

and floor.

Table 4 and test 4 in table 10 show the effect of a higher

basement temperature on the temperatures in the living space

at an outdoor temperature of -13°F, Raising the basement temperature from 37o5°F as in test 1 to 62, ^°F as in test 4 raised

the temperature on the floor surface and at all levels between

floor and ceiling even though the heat output of the furnace

was about 4000 Btu/hr less in test 4° The vertical temperature

difference in the living zone from 2 to 60-inches above the

floor was 12,^°F with the warmer basement as compared to l6,6°F

in test 1,
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Horizontal Temperature Differences

The maximum temperature difference between rooms on a

room-average basis at each level of observation is shown in

tables 1-9. This maximum temperature difference ranged from

7o9°F at an outdoor temperature of -15°F to 3«9°F at an outdoor temperature of 32 ®F at the 30-inch level with gravity

circulation of air through the furnace. The maximum disparity

between rooms decreased from 1 to 1 l/2°F when the booster fan

was used. The maximum difference between average room temperatures was consistently lower at the 30-inch level than at any

other level of observation. The living room was consistently

the warmest room and the north bedroom was consistently the

coldest room at the 30-inch level except for test 3 when the

auxiliary circulating fan forced more warm air through the

doorway connecting the hall and north bedroom.

The maximum temperature difference at the 30-inch level

between any two of the stations in each room is also shown in

tables 1-9* Some of these stations are within 2 feet of the

exterior walls in the north bedroom and range up to 3 1/4 feet

from the exterior walls in the living room. The average of

these maximum temperature differences in the five rooms averaged from 4ol°F at an outdoor temperature of -15°F to 2ol°F

at an outdoor temperature of 32°F at the 30-inch level with

gravity circulation of air through the furnace. Operation of

the booster fan did not affect the temperature variation

within rooms at the 30 -inch level significantly.

When the horizontal temperature differences between

rooms and v/ithin rooms are considered together a value can be

obtained for the maximum variation in temperature at the 30-

inch level between the center of the living room which was

the control point for the tests and the coldest station in

any other room. The values for the maximum horizontal variation in temperature relative to the center of the living

room are plotted in Fig. 6. Fig.6 shows a linear relationship

between maximum horizontal temperature variation and indooroutdoor temperature difference for gravity circulation of air

through the furnace ranging from 6°F to about 11°F as the indoor-outdoor temperature difference increased from 40°F to

SO°F. Use of the booster fan or the auxiliary fan decreased

this maxiraim variation from 1 to 2 degrees at the lowest outdoor temperature used for the tests. As would be expected,

warming the basement decreased this variation significantly.

The use of three supply and return grilles in tests 5 and 6

appeared to decrease the maximum variation of temperature at
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1

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the 30-inch level about 1 degree as compared to operation

with two supply and return grilles under similar conditions.

Fig. 7-10 inclusive were plotted to show the temperature

difference between the center of the living room and the

station most distant from the heater in each room for four

levels above the floor, namely, 2-in, 30 in, 60 in. and 94

in. , as affected by indoor-outdoor temperature difference

and the method of air circulation in the house. For the

most part the horizontal temiperature differences at each

level varied linearly with indoor-outdoor temperature difference for gravity circulation of the air through 2 supply

and return grilles. Fig. 7-10 show that the remote stations

in the bath and two bedrooms which were separated from the

heater by an open doorway were consistently colder relative

to the living room than were the living room and kitchen for

gravity circulation of the air with two supply grilles. Tables 1-3 and 7“9 show that relatively more heat was delivered

to the living room than the other rooms with the 2 grille arrangement used for the tests. This disparity in heat delivery

to the several rooms was caused partly by the larger grilles

in the living room and partly because the bath and two bedrooms had to be heated by flow of air through the doorways

connecting these rooms to the hall. This probably accounts

for a large part of the disparity shown in Fig. 7-10 between

the temperature difference in the living room and that shown

for the other four rooms of the house.

Fig. 7-10 show somewhat greater temperature differences

at the 2-inch level than at either the 30 or 60-inch levels.

This probably reflects the effect of air infiltration in the

lower parts of the rooms and the return of the cold air from

the exterior walls to the heater near the floor surface.

The points plotted in Fig. 7-10 with the subscript ^a”

show the results obtained with gravity circulation of air

through 3 supply and return grilles: in the living room,

hallway, and kitchen. These data show that the temperature

difference between kitchen and living room was decreased considerably at all levels by the use of supply and return

grilles in the kitchen; the temperature differences between

the living room and the two bedrooms and bath were decreased

somewhat less; and the living room was affected only slightly.

The points plotted in Fjg„ 7-10 with the subscript ”b"

show the results obtained with the booster fan circulating

air through the heater and employing 2 supply and return

grilles. The use of the booster fan decreased the temperature
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differences shown in Fig. 7-10 no more than one degree at the

2-inch level, from 1 to 2 degrees at the 30-inch levelo At

the 60-inch level the booster fan had little effect on the

temperature differences in the living room and two bedrooms

and effected a reduction of about one degree in the kitchen

and bath.

The points plotted in Fig. 7-10 with the subscript "c"

show the results obtained with the auxiliary fan circulating

air in the house. The auxiliary fan, directed as it was toward the doorways between the hallway and the two bedrooms,

had its greatest beneficial effect on these two rooms. Fig.

7-10 show that the auxiliary fan reduced the temperature differences at the 2-inch and 30-inch levels in the two bedrooms

to 50 percent or less of the values observed with gravity

circulation whereas there was no reduction of the temperature

differences at the 60-inch and 94-inch levels in these same

rooms. The auxiliary fan had an adverse effect on the temperature differences in the kitchen at the 60-inch level and

only small effects on the temperature differences at the other

levels of observation. The effect of the auxiliary fan on the

temperatures in the living room was small.

A study of Fig. 7-10 shows that the temperature difference between the center of the room containing the temperature

control and the station farthest from the heater in the other

rooms cannot be directly correlated with the distance from

the heater. The temperature difference is more strongly affected by doorways interposed between the heater and the rooms

to be heated, by supply and return grilles serving each room

to be heated, and by circulating fans that direct the heated

air through connecting doorways. The results in the kitchen,

living room, and north bedroom offer a comparison of three

rooms in which the most remote stations of temperature observation were about equally distant from the heater. For the

tests with gravity circulation only the living room of this

group was served directly by a supply and return grille and it

had significantly lower temperature differences than the other

two rooms. In test 5, for which the temperature differences

are identified by the subscript *^a'’ in Fig. 7-10 the kitchen

was also served directly by supply and return grilles but of

smaller size than those serving the living room. In this test

the temperature difference for the kitchen was below that for

the north bedroom which was connected to the hallway by a

doorway; they were also lower than those for the bath in which

the most distant station was only 6 ft from the heater but

which had an intervening doorway; they were greater than those

for the living room presumably because of the difference in

grille size for the two rooms » As noted before the auxiliaryfan, which directed air downward toward the two bedroom

doors, lowered the temperature differences at the 2-inch and

30-inch levels for the two bedrooms to values approaching

those observed in the living room without the auxiliary fano

Total Temperature Difference

The total temperature difference between the 2-inch and

60-inch levels that would be experienced in the entire area

of the house covered by the stations of temperature observation are plotted in Figo 11 <> These values are a combination

of the horizontal and vertical temperature variations and were

determined by subtracting the lowest temperature observed at

the 2-inch level from the highest temperature observed at the

60-inch levelo The values of total temperature difference

ranged from about 14°F for an indoor-outdoor temperature difference of 35°F to about 30°F for an indoor-outdoor temperature

difference of ^0°F» The booster fan produced about the same

values of total temperature difference as gravity circulation

and the auxiliary fan reduced the values of total temperature

difference about 5°F as compared to gravity circulationo

Heat Loss

The relation between the heat loss of the house and the

average indoor-outdoor temperature difference at the 30 "inch

level is shown in Fig„ 12 for the nine tests performed on the

heater o The heat loss observed in tests 2, 6 and 7 with circulation of air by the booster fan averaged about 5% less

than that for gravity circulation of air for the same indooroutdoor temperature difference at the 30-inch levelo The

heat loss of the house with the auxiliary fan was about 10^

less than for gravity circulation for the same indoor-outdoor

temperature difference at the 30-inch level presumably because

the auxiliary fan forced a greater amount of the heat downward

into the lower part of the house and decreased the temperatures near the ceiling as shown in Figo 5° Heating the basement of the house by an auxiliary means as in test 4 decreased

the heat loss of the house by approximately 4500 Btu/hr as

compared to gravity circulation without basement heating for

an indoor-outdoor temperature difference of ^0°Fo This reduction in heat requirement is considerably greater than the

decrease in the heat transmission through the floor caused by

raising the basement temperature from 3^®F to 63 °Fo This apparent discrepancy can be accounted for by the probability

that the infiltration air moving from the basement to the

living space was also being warmed by the auxiliary heater

in the basement.

Measurements of air infiltration were made with gravity

circulation of air through the furnace and with the booster

fan in operation using the tracer gas technique. Values of

lo55 and 2,33 air changes per hour were observed for gravity

circulation and booster fan circulation, respectively, at

an outdoor temperature of about -15°Fo The only logical

explanation that has been suggested for the increase in infiltration with the booster in operation is that it produced

a slightly greater static pressure around the draft diverter

inlet which was in the bonnet of the heater and thus forced

more air out the flue. The change in infiltration rate is

not supported by the heat loss data with and without the

booster in operation indicating that more study of this re^

lationship is needed.

In addition to the heat output from the Royal heater an

average of 0,4 KW of electrical energy for illumination, instrument power and fan operation was dissipated. This electrical energy plus the heat output of one operater contributed from 1540 to 2740 Btu/hr to the heat requirements.

The heat loss from the living space to the attic was

measured with 20 heat flow meters distributed over the total

area so that each represented approximately an equal area.

The observed heat loss through the ceiling, insulated with

5,4 inch of rock wool, averaged about 5 ^ of the total heat

loss of the bourse.

Heater Performance

The results obtained on the performance of the heater

itself are summarized in table 10. Furnace efficiencies of

66 and 6^ percent were observed. The reported furnace efficiencies are based on flue gas analyses and flue gas temperatures observed during continuous operation of the heater. Calculations were made with the values observed below

the draft diverter since incomplete mixing of the flue gases

and room air above the diverter appeared to make observations at this point less reliable. Heat transfer computations indicated that the heater efficiencies actually were

approximately 5 percent higher than those shown in table 10

due to the radiation and convection transfer from the diverter and its components to the heater bonnet and the air

circulated through the heater.
it- '^'

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Comparisons between tests 1 and 2 and between tests 5

and 6 of the temperature rise of the air as it passed through

the furnace indicate that the air circulation was increased

from 20 to 30 percent by the use of the booster fan, A comparison of the air temperature at the supply and return

grilles in tests 2 and 6 indicates that the total air circulation rate was not increased significantly by the use of 3

grilles as compared to that observed with 2 grilles.

The noise levels observed at the center of three rooms

in the Test Bungalow at two different levels above the floor

are summarized in table 11.

¥. Discussion and Conclusions

Several questions naturally arise as to the effectiveness of a heater such as the Royal heaters when used as a

central heating unit for a multi-room house with cvdt her gravity

circulation of air through the heater or using a booster fan

to increase the circulation moderately. Some of these questions might be phased as follows^

1, Are the vertical temperature differences excessive

when the air is circulated by gravity?

2, Are the room-to-room temperature differences excessive because no ducts are used?

3, Is the heat loss of a house equipped with this type

heating unit likely to exceed the computed heat loss because

of large vertical temperature differences?

4, How big a house is this type unit able to heat satisfactorily?

5, Are there climatic limitations to this type of

heating system?

6o Is a booster fan beneficial in extending the application of the unit to larger houses or colder climates or

does it increase the comfort attained in a given house?

The test data do not provide specific answers to all of

the questions, but do provide information on the temperature

distribution produced by this type heating system and some

guidance in its application to small houses.

-13-

The Royal heaters, with or without a booster fan, deliver

a supply of warm air from one or more grilles whose center lines

are typically 7^ to SO inches above the floor level o Since

practically no ductwork is used the heater can deliver warm air

directly into only one, two, or three rooms depending on the

heater location, and there may be one or more rooms that must be

warmed by air movement in both directions through doorways. In

the rooms heated directly by supply grilles the warm air spreads

out over the ceiling and warms the ceiling by conduction and convection which in turn radiates significant amounts of heat to the

floor, walls, and occupants of a house if the ceiling is adequately insulatedo For example, in test 1, the average ceiling

surface temperature in the living room was 102°F<, Studies of a

ciling panel heating system showed that the heat emission from

the ceiling surface at that temperature was on the order of 35

Btu/hr ( sq ft )

«

Since the warmest air is near the ceiling and since very

little warm air is delivered from the heater below the level

of the top of the doorways, the air that can pass to connecting

rooms through doorways is at a lower temperature and therefore

conveys less heat to these roomso There is much less radiation

from the ceiling of rooms heated through connecting doorways.

For example, in test 1, the average ceiling temperatures of the

bathroom and two bedrooms ranged from 75°F to SO°Fo

With gravity circulation of air through the heater none of

the warm air is delivered directly to the lower half 'of the room.

Cooling of the room air at the exterior walls cause a downward

convection current at the exterior walls and the temperature of

the lower part of the room is determined by the temperature of

these downward currents except when appreciable radiation occurs

from the ceiling. The air circulation rate through the Royal

heater by natural convection was between 200 and 250 cfm. This

is probably much less than the total natural downward convection

at all the exterior walls of the house. Consequently, the lower

portion of the rooms could only be warmed as the downward currents of air at the exterior walls become warmer, except for

radiation effects from the ceiling. Since the booster fan increased the air circulation through the heater no more than 20

to 30 percent, it is improbable that the booster fan forced the

warm air into the lower part of the room.

The Test Bungalow has a gross floor area of 6l6 sq ft

which approaches the lower limit of acceptable area for detached single-family dwellings. It has a hallway located
I
-14

very near the center of the building and the heater location

was near the center of the house o The distance from the supply

grille to the most remote doorway to a connecting room was

about 5 feet whereas the distance from the supply grille to the

center of the most remote rooms to be heated was about 11.5 ft.

There was no more than one doorv/ay between the heater and any

room to be heated. Thus, the installation used for the test

is considered favorable to good temperature distribution from

the standpoint of floor area served, heater location, room arrangement, and distance from the heater to each of the connecting doorways.

The test results in tables 5"7, at an outdoor temperature

of about “5°F, show that the Royal heater was able to produce

a temperature of 70°F or higher at the 30-inch level in all

rooms with either two or three supply grilles when the booster

fan was in operation, but did not warm the two bedrooms and

bath to 70°F at the 30-inches level with gravity circulation

of the air. However, the temperature difference between the

2 and 60-inch levels was about 19°F with the booster fan in

operation and 15.5°F with gravity circulation of the air* Experience with this heating system and with other systems, described in BMS 10^ and BMS 114 j indicates that people begin to

experience discomfort if the temperature at the 2-inch level

falls below 65°F or if the temperature at the 60-inch level

exceeds S0°F corresponding to a vertical temperature difference of 15°F in this zone. By this criterion some of the

rooms would be too warm at the 60-inch level with the booster

fan operating and some would be too cold at the 2-inch level

with gravity circulation for the three tests at an outdoor

temperature of -5°F.

In tables 5j 6, and 7 the horizontal temperature differences between rooms on a room-average basis ranged from 5o6°F

to 6.5°F at the 30-inch level, from ^.1°F to 9o7°F at the 60-

inch level, and from 9o9®F to 10.3°F at the 2-inch level.

Fig. 6 shows that the temperature difference at the 30-inch

level between the center of the living room and the coldest

station was appreciably above the values cited above on the

room-average basis, ranging from S.2®F in test 6 to 9o5°F in

test 5o It is common practice among heating engineers to

compute heat losses for dwellinj^on the basis of an indoor

temperature of 70°F. However, it is generally recognized that

in the United States indoor temperatures ranging up to 75°F

are preferred by normally-clothed adults. It is probable that

a variation of temperature between rooms of 5°F at the 30-inch

level would not be excessive as long as none of the temperatures
I

I
» 15»

was below 70°F or above 75°F and provided the vertical temperature differences in the living zone associated therewith

were not excessive. By this criterion the temperature distribution attained in the Test Bungalow with the Royal heaters would hardly be acceptable at an outdoor temperature of

-5°F but would be acceptable at an outdoor temperature of 15°F.

The data in tables 1-9 show that the maximum horizontal

temperature variation within rooms at the 30-inch level averaged about half as much as the maximum horizontal temperature

difference between rooms at the same level on a room-average

basiso This indicates that the temperature difference or temperature head at the 30-inch level required to move the warmed

air across a room was about half as great as that developed

between rooms at the same level when moving warmed air through

a 30 ” by 6^” doorway connecting the hall and a remote room.

This suggests that a limit of one doorway between the heater

outlet and any room to be heated is a valid limitation. It

should be noted in tables 1-9 that the maximum horizontal temperature variations within the four larger rooms of the Test

Bungalow were of about the same magnitude irrespective of

whether the room was heated directly or through a connecting

doorway.

The results observed in the Test Bungalow with the Royal

heaters, for which the maximum distance between the heater

outlet and the center of any room did not exceed 11 1/2 feet,

indicate that the limit of IS feet specified for this distance

in the FHA Minimum Property Requirements Revision No. 51 is a

liberal limit and probably should be reduced. The distance

from the heater outlet to the center of the room in the Test

Bungalow that was consistently the coldest room was only 9 ft.

Probably few installations would have more favorable characteristics than the test installation for good distribution of heat

by this method with respect to floor area, central location of

the hallway, and central location of the heater. However, some

houses of equal or greater size could have a lower heat loss

than the Test Bungalow because more insulation was used which

would tend to decrease the temperature difference between

levels and between rooms. The computed heat loss of the Test

Bungalow is about 51 Btu/hr per sq ft of floor for an indooroutdoor temperature difference of 70®F.

It is concluded from the results obtained with the Royal

heaters in the Test Bungalow that this type of heater should

be used only in areas where the winter design temperature is

0°F or higher even with a booster fan except that application

«16

in colder climates might be satisfactory in some cases in

houses whose heat loss at design outdoor temperatures is significantly lower than 50 Btu/hr per sq ft of floor area. This conclusion is based on the observations that, at an outdoor temperature of -5°F, the heater was not able to produce a temperature

of 70°F at the 30-inch level in the center of all rooms without

the booster fan, the vertical temperature differences were as

high or higher than the limit considered acceptable, the maximum

temperature difference between rooms at the 30-inch level was

a little greater than 5°F and considerably greater than 5°F at

other levels above the floor, and on the opinion that the test

installation is considered generally to be a favorable one for

this method of heat distribution.

The heat loss of the Test Bungalow was computed using the

methods recommended in the 1954 '’Guide’^ of the American Society

of Heating and Air Conditioning Engineers for comparison with

the heat loss observed during the tests. The heat transmission

through the floor, walls, windows and doors, and ceiling and

roof was determined by the conventional formula;

H = kU^T

using computed or tabulated values of the heat transmission

factor, U, after correcting the values for the walls and windows

to a wind velocity of 3 mph which was the approximate velocity

of air motion over the exterior of the house. The infiltration

heat loss was computed on the basis of one air change per hour.

A sample computation for an indoor-outdoor temperature difference of S5°F is shown below.

Computed Heat Loss of Test Bungalow

Heating Load

Element

Area

Sq Ft

U Factor

Btu/hr { ft ) °F]

Temperature

Difference , °F

Heat Less

,

Btu/hr

Outside Walls 667 0,243 S5 13750

Windows and

Doors 13^ 0, S95 10500

Floor 6l6 0 0 144 35 3370

Ceiling and

Roof 6l6 0 0 044 to 2300

Infiltration 5000 cu ft X 0o0lSx^5 7650

Total 37600

17

The heat loss of the Test Bungalow was computed using the

method illustrated above for a temperature difference equal to

the average indoor temperature at the 30=>inch level minus the

outdoor temperature for each of the nine tests » These values

are reported in table lOo On the average the computed heat

loss values are about 5% higher than the observed heat losso

When it is recalled that the heat transmitted to the circulated

air by the draft diverter, which was enclosed in the bonnet of

the heater, is not included in the observed heat loss values

reported, the agreement between computed and observed heat loss

is very closeo

In an installation, such as this one, where there is a

temperature difference between rooms the thermostat might not

be set to produce an average house temperature of 70®F at the

30-inch level, If the thermostat were set to produce a temperature of 70°F in the living room, the heat loss of the

house might be less than the computed value » On the other

hand, if the thermostat were set to produce a temperature of

70°F in the coldest room, the heat loss of the house might be

greater than the computed value o In tests 4, 5 and 6 at an

outdoor temperature of "5°F, the living room i^as about 3o5F

warmer than the house average and the coldest room was about

2o5°F colder than the house average at the 30-inch levelo

Thus, the heat required to warm the coldest room to 70®F might

be about greater than that required to produce a house average of 70°F whereas the heat required to warm the living room,

ioOo the warmest room, to 70®F might be about 5% less than

that required to produce a house average of 70°Fo Since many

people in this country now prefer room temperatures above 70®F,

it is perhaps more likely that the thermostat would be set to

maintain a temperature of 70°F in the coldest roomo

The relation between computed heat loss and required heat

output to adequately warm a house would also be affected by

the accuracy of the infiltration estimate o In the example

shown above, the heat loss corresponding to an infiltration

rate of one air change was 7650 Btu/hr or about 20^ of the

total heat loss. Infiltration measurements showed that the

actual air leakage ranged from 1,5 to 2,3 air changes during

the testSo The effect of this disparity between assumed and

observed air leakage on the heat loss must have been compensated for in the heat loss calculation by other unkrio^vn errors,

otherwise, the computed and observed heat losses would not be

in such good agreement. Similar inaccurate estimates of the

air infiltration rate could accur in the field with less
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fortuitous compensation by other factors with the result

that some cases of underheating might occuro

The test results do not indicate that the heat requirement of a house using a wall heater is significantly greater

than the computed heat loss. The tests do indicate the importance of adequate ceiling insulation because the air temperature near the ceiling is high in the rooms warmed directly

by this method and because radiation from the ceiling plays an

important part in warming the lower part of these rooms. If

the ceiling were uninsulated the ceiling surface would be cooler and less heat would be radiated downward toward the floor.

The booster fan increased the efficiency of the heater

about 2 percent, raised the temperatures appreciably at the

30-inch level in all rooms, and decreased the maximum temperature difference between rooms from 1 to 1 1/2 degrees at the

30-inch level, but it increased the vertical temperature difference in the living zone from 3 to 4 degrees as compared to

gravity circulation. The overall effect of the booster fan

was to increase the comfort a little and to make the heat distribution acceptable at somewhat lower outdoor temperatures.

The Royal heaters were considered acceptable from the

standpoint of noise.
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TABLE

1

Temperature

Distribution

with

Eoyal

Heater,

Gravity

Flow

Outdoor

Temperature

15.2®F

2

Supply

Grilles

«=-fl f-l «

s a p o P H-® -P fl a

S P S3 <u 0} <0 CTN CVJ ^ "H O iH fH (1) a pH

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Pi

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I-I

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m

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TABLE

2

Temperature

Distribution

with

Royal

Heater,

Forced

Flow

Outdoor

Temperature

-

l4,6®F

2

Supply

Grilles

0)^ s

43 43 d d

d d <0 0) SB O IfN CTN tH ^ H o d d 0> a • o 0 0 9 K N « 0> o o r4 VD CT> CO CM

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a

xi o

4S O

Pi O® 'd

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d o

p^ PI

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43

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tnso

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64

n

O', CO CO

ro-d- ^ cy^jt LO''0 I— I— CO

VD rH C\J^ O

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I I CM CM

Average

Attic

Temperature

19.6®F

Average

Ceiling

Surface

Temperat\ire

85,5®^

Average

Floor

Surface

Temperature

59»6®F

TABLE 3

Temperature

DistriTsution

with

Royal

Heater

with

Auxiliary

Fan

Outdoor

Temperature -

13.2®F 2

Supply

Grilles

CO

03

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Average

Basement

Temperat\ire

3S.6°F

Average

Attic

Temperature

15,2®P

Average

Ceiling

Surface

Temperat\ire

77.6®F

Average

Floor

Surface

Temperature

59.6®F
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.ILJ ,,!i ,4 • ^ ^

,jw 8^ ,r»"

;:^r ,> i:

t (-‘ i-- >’ f>!4 B 'S-

•4i’

' 3 • .'4 'H

v'-"i 'a#., . v-^

j^'

4.«4 • .Stf;

if

'

•' 4;

-vy '

-

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,

*

,'^'.V ’ V>'4

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V s-»K.

y

* •f-'- r-

?* (^i " !» -4'

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V»»‘l

• ^ V

V,.

vi, ‘."“U <^i^r

if’’

‘

’ • -v^a

i 'r ^''*-

I
TABLE 4

Temperature

DistriBution

with

Royal

Heaterj

Gravity

Flow

Outdoor

Temperature -

13.4®F 3

Supply

Grilles I 8

4* 4S

a

a o! «D o> ea h (h 0) a ® o > o &«H O B «H ® ® -H fp W en « o _ "H s o m ® o ^ o © © «

=4} ir\ ao

pp

O tS eo ©m

©p

fS©

i*©

ao

XI o

Pi

((o •’d ^ ©Ra

•H o

«H P4 Ma©

Cio

*>

4»

W) ^ O

•H

O

O

© ^ «-s « -< P'1

«H LT\'vD ^ O

O

<r\u5 r<^cr\

oj oj o

CO to VJO (H CO

ft o e • • CO VT) CO U>

U> UD h- CO CT.

CO

|Z! o

CO o• o

CVI iH

P4Ot

lf\ VD

f-l OMT\

r— CO

CO t-1 fH t^O ft o ft ft o CO V«D CO '>0 ir\vX) h- CO

CO

LC> (—i

r-l CU

r'^CU e ft Jt riH C\J

pqo

crNv© I— s^vT)

ft ft ft ft o I^C\I O <H JV£> O fH

C\J© LTN

CO• •

C\J 'X) rH-dPmo

aa©

,£1o

Pi

OM^ CTi C\J OJ O ft ft 0 o LTNCrvCO ITvlTv

VJD viD (T\

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CO CO^

CTN9

CT\ o o o

COm

CO in

VD CO o B* •

ISI

a xi

aO «H VJD

n CO

H R- VX> P o »s O o o ft ft ft R • • « +>

© o © o UT\ CO MD vr» CO o o rH 1

© R m R 0 MO VD r~- CO <T\ w n rH CO P © s R a

-t-> ©

bO P a © § ©

©

h-«

© Ml

a > +» © < «t0 fl EH O• • rH 1^ O -d" vx> ON I I CO CO ©a©©©R

§) 8) © © « ©

Average

Ceiling

Surface

Temperature

88.1®F

Average

Floor

Surface

Temperature

66.0®F

TABLE 5

Temperature

Distrilmtion

with

Royal

Heater^

Gravity

Elow

Outdoor

Temperature -

4.9°^' 3

Supply

Grilles i ®M 0> 0 o

*= Pi

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r^irv ffH cn tr\

pB| • O • • • O O'^ iH

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43 f4 0O

to <i> m

mu

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Pi ^ Pi O 'prti tsi ^ a

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dop

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l-H

4» >

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K\0o • o e • CO LfN iH crs LOtVO f^co to ^ cr» cn o <tn o o o o o K\tO to CT\ IT\

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V-D0*000 LT\^ C\j CO CO CTi MO to O pH

too

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pip <<

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Pi Pi Pi Pi © © © © ^ ^ 4 ^

Surface

Temperature

64,o°P

TABLB

6

Temperature

Distritution

with

Royal

Heaters

Forced

Flow

Outdoor

Ton5

)eratur®

4,5®F

3

Suj^ly

Grilles

§ ai ^ u

3 +» +» Pi a a ed ® ® ea H o ^ © a X M © © > O

W «H Cl,«H •»» o EM a «M © p4 o © °H pq

CTvVX)^ O v£) 1^ > a <1 o o O CTN IT\ CO I

<M C\J

©

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<d o M «H O

® © P4

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a

Xi o ^

rt o «© CO ©

m

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p5 pc!

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l> o

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d

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P=4 o

N

o

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1^o

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0 VD KVO CT\ 00pc! VD 9 cocrv

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0 KV

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COCVJ crvvD

CO CO

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e « » o o irMTv CO VD CO CTi cr>

c\j cr> CO CO ^

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ir\ VD f— CO o

CVJ O Q CO^

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pc! M

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rH IfN

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CVJ

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CO* CO* iH jdr~- CO

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9

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9

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0 ©

d ^© d

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W +» -H O

«3 +> © rH W O

^ S) S) S) © <d © ©

M M M M

9 © © ©

•5 4 <i

TABLE 7

Temperature

Distribution

with

Royal

Heaterj

Forced

Flow

Outdoor

Temperature -

5.0®^ 2

Supply

Grilles 0 mo

«M

O 0) @ Pi

ol

«>

o>ao

8)

a)u

q>

ao

ra »maoo g©^ a> m ^ a ^ o

tmd

a

•HO > O

•H

do4J

4? S

•H

O

O

(D ,0 rH W <J P=4 O

CTi CTvl

O

Pho

PmO

Pmo

PmO

CO CrvlTNCTM^ (H

c\j

U5 CVi NMO h- • « o o e V£> ^ vx> t<r\ '-D r^co CTi o

Ojt r— co^ o e • e e ITS C\J 60 1^

U5 1^60 60 CT\

r^t^vjo lr^

O o e « O cu CM cvj r-c\j

vT) r~-6o to cr>

ITv rH fk6 ir» (H

v.X) r~ to cTv o

CM CM

O 0 0 0 *0

CM to CM^^

I^CTi «-l CM

Pmo

ea©A o CM a e e o O VD t^CM

VJ3 CO CTi

O

CM

OO 60 .d- ix^vr> r— cr>

mo

Pm

S3O

CMO

CM

CO

CM

CTio Jt

VDo Oo r— I—(

CT^ rr-t

CM

<-l O CM * • o o CM r<~\

iH MO

CM ro

cisds

Pm Pm Pm Pm • o » o CO r~ CM MD i^cM cr>uo «d3 S

£5V d 9 & ^ d & ©

CM CT^

d

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cr>

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d

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pu

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TABLE

8

Temperature

Distribution

with

Royal

Heater^,

Gravity

Plow

Outdoor

Ten5

>erature

15,7®P

2

Supply

Grilles

CO 0) o OMD • • • O O sw lf\V£> <M CU

P=i o

CO

evj h~io cvj CO

0 e 0 e e o

P4 o rOVD

e 0

CVJ VO CVJ O us

VO VO CO CO to G

i-t C\J «e^

P»i ^

o^^o •

I

O

CTN fH VvO

• e e e e O VD O -d- to

vjD vx) !—. r—

.

C\Jo oo o O ro

fH <Tn cr> t^MTv

• » O O O cr> 1^10

VO I

1^

CO ^

O CTi

e -it fH cy CTNVO oN VO

at CO CU o O 0 o • ft n 0 o o o«

o ey VO c\j CO to

VO VO 60 §

iH of ot-( 0> iHCU

M

o

p=* o

m

oua

IfN <TN to «H

0 o o e • VO cr»vo to to

VO VD t*~ 0^ O

cr>^ foiojdO O 0 o • (H VO lOfH O VO VO 60 CTv

O‘,vSO CO ^ to' r—ov

ro

oro

CO

CM

t I C\J CVJ

CO VO a o o o • 4) to (Tv VO (p -p to CQ 4^ n ><

§,8)

as os »4 M

0 0

>

lO

< < ^ lO

Average

Ceiling

Surface

Temperature

79,2®P

Average

Floor

Surface

Temperature

62,6®P

TABUS 9

Temperature

Distribution

with

Eoyal

Heater»

Gravity

Flow

Outdoor

Temperature -

31,3®F 2

Supply

Grilles

® es em a

£6 o

«H

Q

©

O «

•xaj lf\ ao

Xi o Om ©mao

S,pd o “d ^ ©

PQ ^ a

-P o

03

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m Pd

t)0 a

a

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O

>.

O

oH rt M

4*

©> o

"H

O

O

© ^ (H W pq 99

pq 9

Pq9

Pq9

Pq9

SB« O <TvC\J OMr^ O « • • o M3 KMOi^ CTN O LT> O O « « O 9 o -Sf r-l CM MD VD t— I— to

CO0 9 9 0 0 CM O CM IT\ M3 M3 r~- 1

Lf^ iH M3 00 9 9 0 9 0 fH M3 cr» «H ir\ M3 M3 M3 I— r^

I-I

O o o • e o J- r~> r4 M3 CTv M3 M3 rIT\0 «3 • 00 ^~03d- M3j:jM3 I— 00 cr»

mo

Pd CM

CM*

CM*

CM

M3

CM*

CM 0^0 CO ^CTv

O oe « CO

iH CM • • 00 ^

CM o • iT\ 5 «-< IH r<A o O o CM C3> 9 0 9 9 0 o 9 9 o ^ h-CM 00 ir\ M3 M3 1^ h- 00 CM 00 O •HM

CM

CM CM

Pq pq • o r~- m

00 ITv • « CM • • r>- CM

Average

Ceiling

Surface

Temperature

76.3®P

Average

Floor

Surface

Temperature

62.6®F
'IsiA , ,' \ !-y

• '

'- > yl

'

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’<•*. 45" in! W‘ >• ••• W'- \ '..Ml *!^,. ww.'• ' "»?;• .•• o '’•»'*; , >' Kit, . ?4S!' .V, .. " - '-" M ^ . .. i,-

' -M . ... :."

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'

'

' 'I,
Test No

Method of i Number of

^ Outside Tei

Observed G< Correction

Corrected < Heating Va!

Heat Input

CO2 in Fluj

Stack Temp

Indirect E|

Heat Outpu'

Electrical

Observed Hi House i Ceiling Hei

Computed Hi House (b

Power Cons'

Blower

Average Tei

Basement A

Attic Air ' Ceiling Su

Avg.Cold M

60 in. a

Floor Surf

Air Temp.

a

Air Temp.

a

(a) An aux

(b) Based
pyV

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»V ""•' Cl

,

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4:. ''S'

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'' >.« vs'lli

ril .„,.

r ' ..i§f M

'

siis: .ss?/' ,

‘ _. r. &>:- ..fiv'

'

. -^ ;.••. n <i«f ,P'; ''• :':

;^rO .W ij’ / i. p§. S.J.':.#- fra . ..*

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' ' ' ',(.

,

'• |y j' 7

' ' '. ' Jift ,..,

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''V,"'i .' '

. I icf'
TABLE 10

SUMMARY OF RESULTS

PERFORMANCE OF ROYAL JET HEATERS

MODELS FG-3-45, FF-3-45

Test No

Method of Air Circulation

Number of Warm Air Outlets

1 2 3a 4

Gravity Booster Gravity Gravity

2 2 2 3

5 6 7

Gravity Booster Booster

3 2 2_

8 9

Gravity Gravity

2 2

Outside Temperature

Observed Gas Consumption

Correction Factor

Corrected Gas Consumption

Heatine: Value

Heat Input to Furnace

CO2 in Flue Gases

Stack Temperature

Indirect Efficiency

”F -15.2

Cu Ft/hr 47.52

1.00

Cu Ft/hr 47.52

Btu/cu ft 1,047

Btu/hr 49,800

% 6.5

op 765

% 66

-14.6 -13.2 -13.4

46.54 45.29 42.78

0.99 0.98 0.97

46.07 44.38 41.50

1,047 1,045 1,051

48,240 46,380 43,620

6.5 6.5

726 7S 5 765

68 66 66

-4.9 -4.5 -5.0 15.7 31.3

45.43 46.02 45.14 29.53 20.58

0.98 0.97 0.97 0.98 0.98

44.52 44.64 43.79 28.94 20.17

1,047 1,047 1,047 1,026 1 ,022

46,610 46,740 45,850 29,690 20,610

6.5 6.7 6.7 6.5 6.5

765 726 726 765 765

66 68 68 66 66

Heat Output of Furnace

Electrical Heat Input

Observed Heat Loss of

House

Ceiling Heat Loss

Computed Heat Loss of

House (b)

Btu/hr

Btu/hr

Btu/hr

Btu/hr

Btu/hr

32,870 32,800 30,590 28,790 30,760 31,780 31,180 19,600 13,600

1,990 1,640 2,350 1,540 1,780 1,890 1,750 2,740 2,670

34,860 34,440 32,940 30,330 32,540 32,670 32,930 22,340 16,270

1,640 1,640 1,400 1,600 1,710 1,670 1,770 1,120 830

34,900 35,880 37,420 36,360 33,050 34,550 35,020 22,570 16,010

Power Consumption of

Blower Watts

Average Temp. 30 in. Level °F

Basement Air Temperature “F

Attic Air Temperature °F

Ceiling Surface Temp. °F

Avg.Cold Wall Temp. 30 to

60 in. above floor °F

Floor Surface Temp. °F

Air Temp. at Return Grilles °F

Air Temp. at Supply Grilles °F

_ 25 _ - - 25

63.7 66.5 71.4 68.8 69.8 73.6

37.5 35.9 38.6 62.8 40.1 38.3

16.8 19.6 15.7 25.5 24.1 27.4

84.5 85.5 77.6 88.1 89.9 93.1

56.7 60.2 61.0 61.7 65.5 70.0

54.4 59.6 59.6 66.0 64.0 66.9

62.0 64.2 78.9 69.3 67.4 69.3

191.5 173.0 190.7 192.7 201.3 176.0

(a) An auxiliary fan was mounted near the heater to direct warm doors.

(b) Based on the average indoor-outdoor temperature difference at the 30-inch level.

25

74.2

38.0

27.1

92.6

69.

66.7

70.7

181.3

66.7 67.5

43.9 47.6

36.5 45.2

79.2 76.3

62.9 64.2

62.6 64.2

68.8 66.8

187.9 151.5

TABLE 11

Summary of Sound Level Measurements in Test Bungalow

With Royal Jet Heater

Height of

Microphone

Above Floor

Room Inches

Weighting

Net Work

Kitchen 60 flat

70

40

Kirchen 24 flat

70

40

Living

Room 60 flat

70

40

Living

Room 24 flat

70

40

South

Bedroom 60 flat

70

40

South

Bedroom 24 flat

70

40

Sound Level

,

Decibels

Background

Burner

on

Burner

Sc Fan

on

Pilot

Only

50 64 63 53

34 51 50 39

24- 36 42 24-

50 56 56 53

34 42 46 39

24” 36 42 24-

46 50 52

31 43 47 - 24- 39 43

4S 50 51 c=. 31 44 47

24- 40 43

50 53 55 e= 37 41 43 - 24- 34 39

50 52 54 Ma 37 42 44

24“ 35 3S -

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