BOILER REPLACEMENT GUIDE - Weil-McLain

BOILER REPLACEMENT GUIDE

Step-by-step procedures for properly sizing hot water and steam replacement boilers for homes and small commercial buildings

BOILER REPLACEMENT GUIDE

INTRODUCTION

This booklet is designed to give the qualityconscious hydronic heating contractor a stepby-step procedure for properly sizing hot water and steam replacement boilers. It is intended primarily for use in sizing boilers for homes, but in many cases can also be used for small commercial buildings.

All too often replacement boilers are sized simply by matching the rating of the old boiler. This can result in an oversized boiler which wastes fuel--or an undersized unit which will not heat the building.

By following the procedures in this booklet, the heating contractor will be able to accurately size replacement boilers, sell more replacement jobs, assure energy-efficient installations, and render better service for customers.

SIZING HOT WATER BOILERS ? Page 3

There is only one accepted method for determining the proper size of a replacement hot water boiler: THE HEAT LOSS OF THE BUILDING MUST BE CALCULATED. By following the steps in this booklet, the total heat loss of the average house can be calculated in five or ten minutes. In most cases it should not be necessary to make a detailed calculation but, if it is required for any reason, use or the latest ASHRAE Handbook.

SIZING STEAM BOILERS ? Page 9

To properly size a replacement steam boiler DETERMINE THE TOTAL BTU CAPACITY OF THE CONNECTED RADIATION. This method is necessary in order to assure adequate steam pressure to fill all parts of the system.

INDEX TO FIGURES & TABLES

PAGE

Figure 1 Job Survey Form

3

Figure 2 Heat Loss Calculation Form

4

Table A Construction Characteristics

4

Table B Heat Loss Table

5

Table C Design Temperature

6

Correction Factors

Table D Ceiling Correction Factors

6

Table E Net Ratings of Weil-McLain Boilers 7

Figure 3 Material List

Figure 4 Job Survey Form-Example

Figure 5 Figure 6

Heat Loss Calculation Form? Example

Radiator Styles

Figure 7 Radiator Example

Table F Radiator Ratings

PAGE 7 8 9 9 10 10

2

SECTION 1 PROCEDURE FOR SIZING HOT WATER BOILERS

STEP 1: COMPLETE A JOB SURVEY FORM

Certain key information is required for each boiler replacement job in order to calculate the heat loss, select the proper boiler and determine the selling price. Figure 1 is a Job Survey Form (part of a Weil-McLain Boiler Replacement Worksheet) to aid in recording the required

information. It will serve as a checklist of the basic data for the existing installation and a permanent record for your job file. Boiler Replacement Worksheets to be used with this booklet are available through Weil-McLain distributors and sales representatives.

FIGURE 1: JOB SURVEY FORM

BOILER REPLACEMENT WORKSHEET

JOB SURVEY FORM

CUSTOMER NAME:

PHONE:

ADDRESS:

PREPARED BY:

DATE:

PRESENT HEATING SYSTEM:

TYPE OF RADIATION:

HEATING MEDIUM:

? Hot Water ? Steam

FUEL NOW USED:

? Natural Gas ? Propane

? #2 Oil

? Electricity

FUEL TO BE USED:

? Natural Gas ? Propane

? #2 Oil

? Electricity

IS SYSTEM HEATING SATISFACTORILY? ? Yes

? No

If no, what is the problem?

How can it be corrected?

RELOCATE BOILER? ? Yes

? No

If yes estimate time

Materials

Corrosive Atmosphere?

PRESENT SOURCE OF DOMESTIC WATER: ? Tankless Heater ? Indirect Tank

? Other

WILL NEW BOILER HAVE A WATER HEATER? ? Yes ? No Type

HOUSE CONSTRUCTION:

GLASS:

WALLS:

CEILING:

SLAB:

HOUSE DIMENSIONS (Use sketch for accuracy):

High Altitude

Ft. Elevation

Basement

' H x

' L x

' W =

Sq. Ft.

First Floor

' H x

' L x

' W =

Sq. Ft.

Second Floor

' H x

' L x

' W =

Sq. Ft.

DESIGN TEMPERATURE DIFFERENCE

?F

NEW THERMOSTAT(S) REQUIRED ? Standard ? Programmable

3

STEP 2: CALCULATE TOTAL HEAT LOSS

The form shown in Figure 2 (Part of the WeilMcLain Boiler Replacement Worksheet) can be used for calculating total heat loss by following these steps.

1. Based on the type of construction, amount of insulation, etc., select the Construction Design Number from Table A below which most nearly matches each of the areas (levels) to be heated.

2. Determine the total square footage of each area to be heated from the Job Survey Form. Round to the nearest hundred.

3. Based on the Construction Design Number selected and the square footage of each area, determine the heat loss (at 70?F design temp. diff.) from Table B (page 5). NOTE: Do not add

in heat loss for basements which are not to be heated; ignore crawl spaces which are open to basement areas.

4. If the Outdoor Design Temperature of the city is unknown, refer to back page. If the design temperature difference is other than 70?F, multiply the heat loss for each area by the appropriate correction factor from Table C (page 6). Round to the nearest ten.

5. If it is a two story house, multiply the heat loss of the first level by the appropriate Ceiling Correction Factor from Table D (page 6). Round to nearest ten.

6. Add the adjusted heat loss for each area to determine the Total Heat Loss.

FIGURE 2: HEAT LOSS CALCULATION FORM

LEVEL FIRST LEVEL

CONSTRUCTION NUMBER

SECOND LEVEL

BASEMENT

SLAB

SQ. FT.

HEAT LOSS (AT 70?F DESIGN

TEMP. DIFF.)

CORRECTION FACTOR AT

?F

x

=

x

=

x

=

x

=

TOTAL

CEILING CORRECTION

FACTOR

ADJUSTED HEAT LOSS

x

=

TOTAL HEAT LOSS

TABLE A: CONSTRUCTION CHARACTERISTICS

FRAME CONSTRUCTION

BRICK CONSTRUCTION

CONSTRUCTION DESIGN NUMBER

1 2 3 4 5 6

7 8 9 10 11 12 13

WEATHERSTRIPPED GLASS

INSULATION THICKNESS

WALL

CEILING

Without basement or crawl space

single

1"

2"

double

1"

2"

single

1"

3"

double

1"

3"

double

2"

3"

double

3"

3"

With full basement or crawl space

double

3"

6"*

double

3"

6"

double

3"

9"

double

3"

12"

double

6"

6"

double

6"

9"

double

6"

12"

CONSTRUCTION DESIGN NUMBER

14 15 16 17

18 19 20 21

22

23

WEATHERSTRIPPED GLASS

CEILING INSULATION

With 4" brick & 4" lightweight block**

single

2"

double

2"

single

3"

double

3"

With 8" brick**

single

2"

double

2"

single

3"

double

3"

For Basements- Concrete or block walls 8' high, 6 1/2' below grade (stray heat from boiler & piping included). Or for unheated crawl spaces

4" concrete slab with 1" perimeter insulation

* With 2" Floor Insulation. ** Furred, lath & plaster. Use for basement heat losses WITHOUT fully exposed walls and for floor losses over closed unheated crawl spaces. For basements with fully exposed walls use FIRST FLOOR heat loss. Use for grade level slab construction.

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TABLE B: HEAT LOSS TABLE (in BTU/Hr.) (Calculated at 70?F Design Temperature Difference

FLOOR AREA SQ. FT. 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

1 28,750 32,300 35,860 39,840 43,340 46,890 50,450 54,000 56,640 60,200 62,830 65,530 68,590 71,720 73,930 77,050

2 23,900 27,030 30,150 33,590 36,680 39,800 42,920 46,040 48,470 51,590 54,030 56,490 59,250 62,040 64,150 66,940

3 27,350 30,620 33,900 37,600 40,820 44,090 47,370 50,640 53,000 56,280 58,630 61,050 63,830 66,680 68,600 71,450

CONSTRUCTION DESIGN NUMBER

4 22,510 25,350 28,190 31,350 34,160 37,000 39,840 42,680 44,830 47,670 49,830 52,010 54,490 57,000 58,830 61,340

5 18,080 20,520 22,970 25,640 28,050 30,500 32,940 35,390 37,340 39,790 41,740 43,730 45,910 48,130 49,860 52,080

6 16,860 19,200 21,540 24,080 26,380 28,720 31,060 33,400 35,300 37,640 39,540 41,480 43,570 45,710 47,410 49,550

7 17,910 20,460 23,010 25,760 28,270 30,820 33,370 35,920 38,030 40,580 42,690 44,840 47,140 49,490 51,400 53,750

8 16,160 18,360 20,560 22,960 25,120 27,320 29,520 31,720 33,480 35,680 37,440 39,240 41,190 43,190 44,750 46,750

9 15,460 17,520 19,580 21,840 23,860 25,920 27,980 30,040 31,660 33,720 35,340 37,000 38,810 40,670 42,090 43,950

10 15,110 17,100 19,090 21,280 23,230 25,220 27,210 29,200 30,750 32,740 34,290 35,880 37,620 38,410 40,760 42,550

11 15,360 17,490 19,610 21,920 24,010 26,140 28,270 30,400 32,120 34,240 35,970 37,730 39,630 37,950 43,120 45,070

TABLE B (continued)

FLOOR AREA SQ. FT. 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

12 14,660 16,650 18,630 20,800 22,750 24,740 26,730 28,720 30,300 32,280 33,870 35,490 37,250 39,060 40,460 42,270

13 14,310 16,230 18,140 20,240 22,120 24,040 25,960 27,880 29,390 31,300 32,820 34,370 36,060 37,800 39,130 40,870

14 30,360 34,060 37,760 41,920 45,560 49,260 52,960 56,660 59,360 63,060 65,770 68,540 71,710 74,950 77,190 80,420

15 25,520 28,790 32,050 35,670 38,910 42,170 45,430 48,690 51,200 54,460 56,970 59,500 62,370 65,270 67,410 70,310

CONSTRUCTION DESIGN NUMBER

16

17

18

19

28,960 24,120 32,780 27,940

32,380 27,110 36,690 31,420

35,780 30,090 40,600 34,890

39,680 33,430 45,040 38,790

43,040 36,390 48,890 42,240

46,460 39,370 52,810 45,720

49,880 42,350 56,720 49,190

53,300 45,330 60,630 52,670

55,720 47,560 63,450 55,290

59,140 50,540 67,360 58,760

61,570 52,770 70,180 61,380

64,060 55,020 73,050 64,020

66,950 57,610 76,390 67,050

69,910 60,230 79,780 70,110

71,870 62,090 82,080 72,300

74,820 64,710 85,470 75,360

20 31,380 35,010 38,650 42,800 46,370 50,010 53,640 57,270 59,810 63,440 65,980 68,570 71,630 74,740 76,760 79,870

21 26,540 29,740 32,930 36,550 39,720 42,920 46,110 49,310 51,650 54,840 57,180 59,540 62,290 65,070 66,990 69,760

22 5,130 6,150 7,180 8,210 9,230 10,250 11,300 12,330 13,340 14,370 15,400 16,420 17,440 18,480 19,500 20,600

23 4,350 4,730 5,220 5,600 5,980 6,370 6,750 7,150 7,330 7,720 7,920 8,110 8,400 8,690 9,270 9,560

NOTE: The BTU figures in this table are based upon AHRI NET calculations where ceiling height is 8 ft. and where total window and door areas do not exceed 20 percent of the GROSS wall area. For 9 ft. ceiling height add 11 percent to heat loss; for 10 ft. ceiling height, add 22 percent. For lower levels ONE HALF or LESS below grade level, use FIRST FLOOR heat loss.

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