Weil-McLain Evergreen EVG 220 Manual page 40

®
gas
Install water piping
System water piping methods
All piping methods shown in this manual use
primary/secondary connection to the boiler loop.
These designs ensure proper flow through the
boiler, for the most efficient and reliable operation
of the boiler and the heating system. For other
piping methods, consult your local Weil-McLain
representative or see separate boiler piping guides.
Circulators
The boiler circulator (Taco 0014 for Evergreen
300; Taco 0013 for Evergreen
in the boiler outlet, as shown in the appropriate piping diagram
in this manual.
DO NOT
use the boiler circulator in any location
other than the ones shown in this manual. The
boiler circulator is selected to ensure adequate flow
through the boiler.
Failure to comply could result in unreliable perfor-
mance and nuisance shut downs from insufficient flow.
System circulators and zone
circulators
Install a system circulator or zone circulators as shown in the
piping diagrams in this manual. These circulators must be sup-
plied by the installer.
System or zone circulator flow rate
1. Size circulators based on the flow rate required to achieve the
temperature change needed.
2. You can closely estimate temperature rise (or drop) through a
circuit by using the following formula, where TD is tempera-
ture rise (or drop), FLOW is flow rate (in gpm), and BTUH
is the heat load for the circuit:
FLOW =
Example
:
Consider a system loop for a system with total heating load equal
to 210,000 Btuh. The desired temperature drop through the sys-
tem piping is 20°F. Then the required flow rate is:
210,000
FLOW = —–—–—–—–
20 x 500
SIMPLIFIED:
For 20° temperature drop, FLOW = MBH / 10.
System or zone circulator head requirement
1. The circulator must be capable of delivering the required flow
against the head loss that will occur in the piping.
2. Determine the pipe size needed and the resultant head loss
using accepted engineering methods.
3. The simplified pipe sizing here is limited to residential sys-
tems, and does not include systems with fan coil units or
radiant tubing.
– 40 –
-
fired water boiler
(continued)
®
220, 299 and
®
399) is shipped loose. Locate it
BTUH
—–—–—–—–
TD x 500
= 21 gpm
— 220/299/300/399 Boiler Manual
The following simplified method for pipe and
circulator sizing must be limited to residential ap-
plications using baseboard (finned or cast iron),
cast iron radiators or convectors. DO NOT apply
for radiant heating, fan coil units or commercial
installations.
Simplified pipe/circulator selection
1. Install the boiler and piping using the recommended piping
layouts shown in this manual.
2. Size the piping and components for each circuit in the space
heating system using Figure 49, page 41.
listed, the head loss in all piping will be 0.04 feet per
foot of pipe.
ermine the heating load (Btuh) for each circuit.
a. Det
b. Calculate the flow rate for each circuit using its load.
c. To use a 20°F temperature drop, just divide the
MBH (1,000's of Btuh) by 10.
d. Example — Flow for 20°F temp drop with 35,000 Btuh:
e. Find the pipe size in Figure 49, page 41 that has a max
flow rate just larger than that required for the circuit.
f. Find the total equivalent length (TEL) of the circuit.
g. TEL accounts for losses through fittings and valves by
using the equivalent length of pipe that would cause
the same head loss. Add these numbers to the measured
length of the circuit to find TEL in feet.
TEL is usually close to 1.5 times the length of the
h.
circuit for residential baseboard, radiator or con-
vector applications.
i. Measure the length of each circuit from the circulator
outlet back to its inlet. Then multiply this length times
1.5 to get the approximate TEL of the circuit.
j. Find the head loss for
TEL = 1.5 X Circuit Length (feet)
HEAD = TEL X 0.04
: Size system header piping for the total flow of all
k. NOTE
connected zones.
3. Example:
a. For a circuit with heating load = 45,000 Btuh (= 45 MBH).
Measured length of circuit is 88 feet.
b. Flow = 45 MBH / 10 = 4.5 gpm.
c. TEL = 1.5 x 88 feet = 132 feet.
d. From Figure 49, page 41, select 1" pipe (max flow = 7.1
gpm).
e. Head loss = TEL x 0.04 = 132 x 0.04 = 5.28 feet.
f. Select a circulator that can deliver at least 4.5 gpm at a
head of 5.28 feet. (Read the NOTICE below.)
To use this method, limit the flow through ¾"
finned-tube baseboard to 3.9 gpm, or use 1" base-
board and limit flow to 7.1 gpm. If the total load
of the circuit requires more flow, split the circuit
into two or more.
At the flow rates
FLOW = 35 MBH / 10 = 3.5 gpm
each circuit:
(feet water column)
Part number 550-100-131/0120