Weil-McLain GV90+ Installation And Start-Up Manual page 15

GV90+ Series 2
OAS·FIRED WATER BOILER -
Boiler Manual
Install water piping
(continued)
Syste m wat e r p iping m e thods
NOTICE
Most p iping methods shown in thi.s manual u.se
p rimary/secondary connection to the boiler loop.
These designs ensure proper flow through the
GV90+
boiler, for the most
effkient and reliable
oprration of the boiler and Lhe heating system.
For other piping methods> consult your local Well-
McLain rtprtktltath•e.
Circula tors
IAWARNINGI
Do
not remove either
of the GV90+ internal pumps
for
u.st
elsewhere in the system. Both pumps art
rtqu-irtd for proper operation. Remo\•ing a pump
will cause the boiler
to
malfunction. Subsrantial
p roperty damage could result.
Ntver Install another pump In . . - . wtth
the
GV90+ bollcw. Forced flow can cause improper op-
erarioon of rhe boiler controls. Substantial prope-rry
damage could rtsult.
Failure
to
comply could result in unre-liable
~rfor­
maJKe and nuisance shutdowns from insuffident
flow.
Circulator flow rate
Size system c. i rculators based on the flow rate required to ac.b..ieve
r.he temperature change needtd. You can closely estimate tem-
perature rise (or drop} through a circuit by using rhe following
formula, where TD is temperature rue (or drop), FLOW u flow
rate (in gpm). and BTUH
is
the hear load fo r the circuit:
FLOW
=
BTUH
TD
X
600
Examplu:
Consider a system loop for a system with rot:al heating load equal
to 210,000 Btuh.
Tbe desir<d temperature drop through
the system
piping is 20'F. Then the required flow rate is:
210,000
FLOW
=
=
21
gpm
20x 600
SIMPUREO: For 20" IOJTC)oraturo drop, FLOW • MBH /10.
Circulator head requirement
The circulator
mUISt
be
capable
of
delivering the
required
flow
against the head L oss that will occur in
the
piping. Dt-termine
r.he pipe site needed and r.he resultant head loss using accepted
engineering methods. The slmpllfied pipe
~z.ing
here
is
limited
ro residential systems. and does not include systems with fan coil
units or radiant tubing.
IAcAumNI
The following sim pUfied method for pipe and cir-
cuJaror si:z:ing must be limited ro residential applica-
tionsusingbaseboard (finned or cast iron), cast iron
radiatOrS or COn\rtctors. DO NOT apply for radtant
heati ng. f.m coil unirs or commercial installations.
Part number 550-1+2-783/1012
Simplifie d pipe/circula to r selection
t.
lnsrall r.hr boiler and piping using the recommended piping
layours in r.his manual.
2. Site r.he piping and compontnrs for each circuit in rhe space
heating system using Figure- 16. At
the flow
rates lsted, the
head IOOoSin all piping wtll bo 0.041oot per foot of piP<>-
a. Dettrmint r.he heating load (Btuh) for each circuit.
b. Calc.ulate the flow rate for each drc.uit using its load
To use a 200F temperature drop, just divide rhe
MBH (I,OOO's ofBtuh) by 10.
Example - Flow fo r 20'F temp drop with 35,000
Btuh:
FLOW= 35 MBH
I
10 = 3.5 gpm
c. Find the pipe site in Figure I 6 that has a max flow rate
just larger than thar required for the circuit.
d. Find r.he t:Otal equh·alent lengr.h
(TEL)
oftht circuit.
TEL accounts for losses through 6ttin(!'
and
valves
by
using the equivalent length of pipe r.hat would cause
the same head loss. Add tllese numbers ro rhe
measu~d
length of the circuit to find TEL in feet.
TEL Is usually_ close to 1.5 times the length of the
circuit for residential baseboard, radiator or convec·
tor applicstions.
e.
Measure- r.he ltngth of each circuit from rhe circulator
oudet bsdc to irs inlet. Then muldpl)• this length times
1..5
to
ger tht approximate
TEL
of the circuit.
f. Find r.he head loss fo r each circuit:
TEL • 1.5 X
Circuit
Length (feet)
H EAO • TEL X 0.04
(feet
wate< column)
g. NOTE.: Siu system """der piping for the total flow of
aU connected
z.ones.
3. Example:
a. For a circuir with heating load= 45,000 Btuh (= 45
MBH). Measur<d length of circuit
is
88 fffi.
b. Flow= 45 MBH / 10 = 4.5 gpm.
c. TEL= 1.5 x 88 feet = 132 fe.t.
d. From Figure 16, seifct I" pipe (max flow= 8 gpm).
e. Head loss = T EL x 0.04 = 132 x 0.04 = 5.28 fe.t.
f. Selecr a circulator that can deliver ar least 4.5 gpm at a
head of 5.28 feeL (Read the NOTICE below.)
NOnCE
To use
this
method, limit the flow tbrou3:h
l4"
finned-tube baseboard to
3.9
gpm,or use I base-
board and limit flow to 7.1 gpm.
If the total load
of the c. i rc.uit requires more flow, split the drc.uit
into cwo or mort .
Figure
16 Flow ra tes
tor
0.04
fMt
hfHid
Joss,.,-
foot
of
<:Opper p ipe
(based
oo
water at
140"F)
Pipe size
MAX-- (GPt.l)
Pipe size
MAX-- (GPt.l)
(lnctoas)
• 0.04 ... per loot
(lnctoas)
• 0.04 ... per loot
~
4 2
45
1
8
:lli
75
114
I
14 3 140
11\ 22
•
290
15