Burnham 4FHL-63A - Tankless Heater Piping; Flow Regulation

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Flow Rate Based On Delta-T
APPROXIMATE BOILER WATER FLOW
RATE REQUIRED (GPM) – SERIES 4FH
BOILER SIZE
(bhp)
20º Delta T 30º Delta T 40º Delta T
63A 43 29 22
78A 53 36 27
92A 63 42 31
107A 73 49 37
127A 87 58 44
154A 106 71 53
180A 124 83 62
209A 144 96 72
240A 166 111 83
277A 192 128 96
311A 216 144 108
345A 241 161 120
360A 251 168 126
450A 317 211 158
563A 400 267 200
675A 483 322 242
827 591 394 295
993 708 472 354
1157 823 549 411
1323 939 626 469
1654 1166 777 583
1985 1399 933 700
2315 1638 1092 819
2645 1878 1252 939
3075A 2186 1457 1093
Boiler Waterside Pressure Drop
Due to the large internal water reservoir and
a design having very little ow restriction, the
waterside ow pressure drop is less than 1 psi.
This is applicable to all ow rates, including the
highest ow rate corresponding with a 20ºF delta T.
B. Steam Supply Connection & Piping
Most steam boilers are supplied with a anged
steam outlet connection, with the exception of the
smallest boilers, which may have a threaded pipe
connection. All low pressure steam boilers (15
psig) are supplied with a class 150 anged steam
connection. All high pressure steam boilers (over
15 psig) are supplied with a class 300 anged
steam connection.
2. RECOMMENDED WATER BOILER
RECIRCULATION LOOP
The following guidelines relating to system water
temperature uctuation and ow through the boiler
must be observed.
A. It is important to operate your boiler in such a
manner as to prevent temperature uctuation of
more then 40°F at any time. Rapid temperature
changes within the boiler can create stresses
in the boiler metal. These stresses can cause
damage to the boiler by loosening tubes, or
in more severe instances can crack tube sheet
ligaments,furnaces, or waterlegs.
B. If temperature differentials approach 40°F,
to help prevent temperature uctuations and
insure proper circulation through the boiler, a
recirculation loop as shown in Figure 3 should be
considered. The recirculation ow should be at
least 1/2 GPM/BHP at all times when the boiler is
online for operation.
3. TANKLESS HEATER
Install an automatic mixing valve at the tankless heater
outlet to avoid risk of burns or scalding due to excessively
hot water at the xtures. Adjust and maintain the mixing
valve in accordance with the manufacturer’s instructions.
Installer une vanne mélangeuse automatique au chauffe-
eau sans réservoir pour éviter les risques de brûlure
causés par une température excessive de l’eau dans la
plomberie. Ajuster la vanne mélangeuse conformément
aux instructions du fabricant, et la maintenir ainsi.
A. If boiler is ordered with tankless heater, connect
tankless heater piping as shown in Figure 2.
B. The following guidelines should be followed when
piping the tankless heaters:
4. FLOW REGULATION
If ow through the heater is greater than its rating,
the supply of adequate hot water may not be able to keep up
with the demand. For this reason a ow regulator matching
the heater rating should be installed in the cold water line to
the heater. The ow regulator should preferably be located
below the inlet so it's not subjected to excess temperatures
that may occur during “off” periods when it is possible for
the heat to be conducted back through the supply line. The
ow regulator also limits the ow of supply water regardless
of inlet pressure variations in the range of 20 to 120 psi.