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4ABLE Boiler feed system sizing
&IGURE Recommended piping for parallel-flow systems
with optional reservoir pipe
3DUW1XPEHU
19
Condensate return
Modern steam boilers are designed to steam for less time than
older, larger boilers. When replacing an older steam boiler the
system condensate return time may be longer than the steaming
time. This could cause the following problems:
1. Boilers fitted with an automatic water feed could overfill.
2. Units fitted with only a low water cutoff would shut down
and cycle while waiting for condensate to return.
Following is a simple method for determining whether or not a
reservoir pipe is required to lengthen steaming time for a resi-
dential installation:
1. Disconnect condensate return line at existing boiler.
2. Heat
boiler and allow to steam for 10 minutes. Turn off boiler.
3. Measure length of time from when boiler started to steam to
when condensate begins to return through condensate line.
4. Measure length of time from when condensate begins to
return to when it stops returning. Divide this time by 2.
5. Add time measured in step 3 to time calculated in step 4. This
sum is the average time required for condensate to return to
the boiler.
6. If this total time is 10 minutes or less, no reservoir pipe is
needed.
If total time for condensate to return to boiler (from step 5) is
more than 10 minutes, a reservoir pipe (or boiler feed system) is
RECOMMENDED3EE4ABLEAND&IGUREFORSUGGESTEDRESERVOIR
pipe size. Install as shown in Figure 20.
&ORLARGERSYSTEMSASNOTEDIN4ABLEUSEABOILERFEEDSYSTEM
with a condensate tank and feed pump. You will have to install a
low water cutoff/pump control on the boiler to operate the pump.
Use Table 9 to size boiler feed systems. See Figure 5, page 10, for
tapping locations. (The use of a combination condensate tank and
float-controlled condensate return pump is not recommended.)
For most residential installations a reservoir pipe may be all that
is necessary to ensure proper operation.
Boiler
model
number
Max.
boiler
gross
output
Time from initial steaming to average condensate return
ERLOHUVWHDPLQJFDSDFLW\EDVHGRQ%WXSHUSRXQGRIVWHDP
15 minutes 20 minutes 30 minutes
MBH gallons
pipe
length
(feet)
gallons
pipe
length
(feet)
gallons
pipe
length
(feet)
EG/PEG-30,-35
75 ¾ ¾ 1 ½ 1 ½ 3 2 ½
EG/PEG-40,-45
125 1 ¼ 1 ¼ 2 ½ 2 ¼
8VHERLOHUIHHG
V\VWHP
EG/PEG-50
145 1 ½ 1 ½ 3 2 ½
EG/PEG-55
167 1 ¾ 1 ¾
8VHERLOHUIHHG
V\VWHP
EG/PEG-65
209 2 ¼ 2 ¼
EG-75
247 2 ½ 2 ½
EGH-85
243 2 ½ 2 ½
EGH-95 up Not recommended –– Use boiler feed system if needed
'HVLJQHGIXOOFDSDFLW\VWHDPLQJWLPHRIPRGHUQERLOHUVLVPLQXWHV
4ABLE Reservoir pipe sizing
Boiler
Model
Gross
Output
Pounds
Steam
Per
Hour
Gallons
Conden-
sate
Per
Hour
Minimum Condensate
Receiver Capacity (Gal.)
Recom-
mended
Maximum
Minutes of boiler
operation:
Feed
Pump
Capacity
GPM
*
15 30 45 60
EG/PEG-30
65 7 ½ 2 5 7 10 0.3
EG/PEG-35
86 10 3 7 10 13 0.3
EG/PEG-40
108 12 ½ 4 8 12 17 0.4
EG/PEG-45
130 15 5 10 15 20 0.5
EG/PEG-50
151 17 ½ 6121723 0.6
EG/PEG-55
174 20 7 13 20 27 0.7
EG/PEG-65
218 25 8 17 25 33 0.8
EG-75
257 29 ½ 10 20 29 39 1.0
EGH-85
253 29 10 19 29 39 1.0
EGH-95
290 33 ½ 11 22 33 45 1.1
EGH-105
325 37 ½ 12 25 37 50 1.3
EGH-115
361 41 ½ 14 28 41 55 1.4
EGH-125
398 46 15 31 45 61 1.5
*
,ISXPSFDSDFLW\H[FHHGVFDSDFLW\VKRZQSXPSFDQ
EHWKURWWOHGZLWKJOREHRUEDOOYDOYH
ConneFt pLpLnJ ² steam EoLlers (continued)
EG
&
PEG SERIES 5
s
EGH SERIES 5 GAS-FIRED BOILERS — BOILER MANUAL
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