Recommendation 3 – Crown Series 24 User Manual
Page 7
Recommendation 3
is used when the return water temperature goes below 135°F for prolonged periods of
time. This is also primary-secondary piping, but includes the addition of a 3-way valve, return water sensor and
boiler-mounted RTC Return Temperature Control.
RETURN PIPING SIZE (IN)
SUPPLY
RETURN
RETURN
PIPING
HEADER
BRANCH
SIZE (IN) (1)
RETURN (2)
(2A)
(QTY.) SIZE (2B)
BOILER
20°F
40°F
20°F
40°F
20°F
20°F
MODEL
DROP
DROP
DROP
DROP
DROP
DROP
24-03
2
1-1/2
2
1-1/2
–
–
24-04
2
1-1/2
2
1-1/2
–
–
24-05
2
1-1/2
2
1-1/2
–
–
24-06
2-1/2
1-1/2
2-1/2
1-1/2
–
–
24-07
2-1/2
2
2-1/2
2
–
–
24-08
2-1/2
2
2-1/2
2
–
–
24-09
3
2
3
2
–
–
24-10
3
2-1/2
3
2-1/2
–
–
24-11
3
2-1/2
3
2-1/2
–
–
24-12
4
2-1/2
4
2-1/2
3
(2) 3
Notes:
1. All piping is schedule 40.
2. Pipe sizes listed are based on a 20° F or 40°F differential (temperature drop).
Select one to match application.
3. When specified return piping is less than 3”, install 3” x 12” nipple and appropriate
size bell reducer directly into boiler return tapping as shown.
4. Drain valve—ball valve preferable, gate valve acceptable alternative
(supplied by others).—Minimum valve size per ASME code is 3/4” NPT.
5. Maximum linear feet of pipe from 3-way bypass port to sensor location = 11 feet.
Bypass line shall be the same diameter as return A.
6. Minimum linear feet of pipe from point of mixing (where bypass meets return line)
to sensor location = 4 feet.
7. Install special 3” x 12” nipple with 1/4” NPT side tapping closest to boiler.
Where applicable, use bell reducer to adapt to recommended return pipe size.
8. Proper boiler circulator sizing is listed in RTC literature.
24-03 THRU 24-11 (W/20°F DROP)
24-03 THRU 24-12 (W/40°F DROP)
24-12 (W/20°F DROP)
BOILER CIRCULATOR
(BY OTHERS - SEE NOTE 5)
DRAIN VALVE
(SEE NOTE 4)
SUPPLY
DIVERTING
VALVE & ACTUATOR
SUPPLY
1
BOILER CIRCULATOR
(BY OTHERS - SEE NOTE 5)
DRAIN VALVE
(SEE NOTE 4)
SUPPLY
1
1
3
DIVERTING
VALVE & ACTUATOR
3
2
2
SYSTEM
PUMP
CLOSELY
SPACED
TEES
D
MAX
4D
REAR OF
BOILER
REAR OF
BOILER
RETURN
RETURN
RETURN
SENSOR
(SEE NOTE 7)
RETURN
SENSOR
(SEE NOTE 7)
3” x 12” NIPPLE
AND BELL REDUCER
(SEE NOTE 4)
SEE NOTE 6
SEE NOTE 5
SUPPLY
1
2B
2A
RETURN BRANCH
SYSTEM
PUMP
CLOSELY
SPACED
TEES
D
MAX
4D
2
2
RETURN
RETURN HEADER
RETURN
SEE NOTE 6
SEE NOTE 5
24-03 THRU 24-11 (W/20°F DROP)
24-03 THRU 24-12 (W/40°F DROP)
24-12 (W/20°F DROP)
BOILER CIRCULATOR
(BY OTHERS - SEE NOTE 5)
DRAIN VALVE
(SEE NOTE 4)
SUPPLY
DIVERTING
VALVE & ACTUATOR
SUPPLY
1
BOILER CIRCULATOR
(BY OTHERS - SEE NOTE 5)
DRAIN VALVE
(SEE NOTE 4)
SUPPLY
1
1
3
DIVERTING
VALVE & ACTUATOR
3
2
2
SYSTEM
PUMP
CLOSELY
SPACED
TEES
D
MAX
4D
REAR OF
BOILER
REAR OF
BOILER
RETURN
RETURN
RETURN
SENSOR
(SEE NOTE 7)
RETURN
SENSOR
(SEE NOTE 7)
3” x 12” NIPPLE
AND BELL REDUCER
(SEE NOTE 4)
SEE NOTE 6
SEE NOTE 5
SUPPLY
1
2B
2A
RETURN BRANCH
SYSTEM
PUMP
CLOSELY
SPACED
TEES
D
MAX
4D
2
2
RETURN
RETURN HEADER
RETURN
SEE NOTE 6
SEE NOTE 5
Series 24 Minimum Piping Recommendations – Steam Boiler
Notes:
1. All piping is schedule 40.
2. To prevent condensate from being trapped in header, do not reduce equalizer elbow at header
connection.
3. Drain/blowoff valve—ball valve preferable, gate valve acceptable alternative (supplied by others).
• Mininim valve size per ASME code is 3/4” NPT 24-03/24-05; 1” NPT 24-06/24-10;
1-1/4” NPT 24-11/24-12.
• Increasing the valve size will improve the blowdown operation
• In all cases, piping connection blowoff valve to boiler should be full size to the point of discharge.
4. For pumped return systems, see Series 24 installation manual.
RISER
PIPING SIZE (IN)
SPACING (IN)
RISER
HEADER
BOILER
(QTY.)
& SUPPLY RETURN
EQUALIZER
MODEL
SIZE (1)
(2)
(3)
(4)
‘A’
‘B’
24-03
(1) 3”
3”
1-1/2”
2”
–
–
24-04
(1) 4”
4”
2”
2”
–
–
24-05
(1) 4”
4”
2”
2”
–
–
24-06
(1) 4”
4”
2-1/2”
2-1/2”
–
–
24-07
(2) 4”
6”
2-1/2”
2-1/2”
36”
–
24-08
(2) 4”
6”
2-1/2”
2-1/2”
42”
–
24-09
(2) 4”
6”
2-1/2”
2-1/2”
48”
–
24-10
(2) 4”
6”
3”
3”
54”
–
24-11
(2) 4”
6”
3”
3”
60”
–
24-12
(3) 4”
6”
3”
3”
30”
36”
24-07 THRU 24-11
24-12
24-03 THRU 24-06
(SEE NOTE 4)
(SEE NOTE 4)
(SEE NOTE 5)
(SEE NOTE 5)
(SEE NOTE 5)
(SEE NOTE 3)
SEE NOTE 2
(SEE NOTE 3)
RISER
WATER LINE
EQUALIZER
CLOSE NIPPLE
24” MIN.
18” MIN.
HARTFORD LOOP
(REQ’D ON GRAVITY
RETURN SYSTEM)
REAR OF BOILER
BLOW-OFF/
DRAIN VALVE
(SEE NOTE 3)
DRAIN VALVE
(WET RETURN)
2” TO 4”
SUPPLY
1
1
1
3
3
4
4
4
3
2
2
2
2
2
2
‘A’
‘A’
‘B’
RETURN
HEADER
(SEE NOTE 4)
24-07 THRU 24-11
24-12
24-03 THRU 24-06
(SEE NOTE 4)
(SEE NOTE 4)
(SEE NOTE 5)
(SEE NOTE 5)
(SEE NOTE 5)
(SEE NOTE 3)
SEE NOTE 2
(SEE NOTE 3)
RISER
WATER LINE
EQUALIZER
CLOSE NIPPLE
24” MIN.
18” MIN.
HARTFORD LOOP
(REQ’D ON GRAVITY
RETURN SYSTEM)
REAR OF BOILER
BLOW-OFF/
DRAIN VALVE
(SEE NOTE 3)
DRAIN VALVE
(WET RETURN)
2” TO 4”
SUPPLY
1
1
1
3
3
4
4
4
3
2
2
2
2
2
2
‘A’
‘A’
‘B’
RETURN
HEADER
(SEE NOTE 4)
24-07 THRU 24-11
24-12
24-03 THRU 24-06
(SEE NOTE 4)
(SEE NOTE 4)
(SEE NOTE 5)
(SEE NOTE 5)
(SEE NOTE 5)
(SEE NOTE 3)
SEE NOTE 2
(SEE NOTE 3)
RISER
WATER LINE
EQUALIZER
CLOSE NIPPLE
24” MIN.
18” MIN.
HARTFORD LOOP
(REQ’D ON GRAVITY
RETURN SYSTEM)
REAR OF BOILER
BLOW-OFF/
DRAIN VALVE
(SEE NOTE 3)
DRAIN VALVE
(WET RETURN)
2” TO 4”
SUPPLY
1
1
1
3
3
4
4
4
3
2
2
2
2
2
2
‘A’
‘A’
‘B’
RETURN
HEADER
(SEE NOTE 4)
PIPE SIZING AND NOTES FOR RECOMMENDATION 3