Weil-McLain Ultra Manual page 22

-
gas fired water boiler
Install water piping
Sizing DHW system piping
Weil-McLain PLUS water heaters
For
the installation manual for PLUS, GOLD PLUS, Ultra
PLUS and other Weil-McLain heaters for application
information. The information here is for other water
heater designs.
When using the Ultra boiler for dedicated DHW applica-
tions, use the circulator supplied with the boiler (007 for
Ultra-80/105; 0014 for Ultra-155/230/310) to circulate to
the water heater, except where higher flow rates may be
required for the heater used. Use the following method
to select a circulator for the water heater on combined
space heating/DHW systems.
1. To pipe the DHW tank and boiler, follow the suggested piping
diagrams beginning on page 17.
2. Figure 23, page 23 shows the pump curves for typical DHW circu-
lators. Use these curves along with boiler pressure drop data from
Figure 22, page 23 to size the DHW piping and circulator.
3. Procedure to select a DHW circulator:
Step 1
:
From the water heater manufacturer's data, find:
• Required boiler water flow rate, GPM, at 190°F.
• Pressure drop across the water heater at this flow rate, in feet
water column.
Step 2
:
Find your boiler model in Figure 22, page 23.
Select a flow rate in the Flow rate column just larger than the
required boiler water flow rate from Step 1.
Step 3
:
Read across the row selected to find the boiler pressure drop, H1,
and the pressure drop in the piping, H2. Make sure to use the cop-
per pipe size given in column 3 when piping the water heater.
Step 4
:
Add the pressure drop across the water heater, from Step 1, to the
values of H1 and H2 for total head loss.
= H1 + H2 + H3
H
total
Step 5
:
Select a circulator that can deliver the required flow rate, gpm,
against the total head loss found in Step 4.
Example
:
Consider an Ultra-155 used with a water heater that requires a
flow of 12 gpm with boiler water at 190°F. The water heater is to
be piped as in Figure 20.
From the example water heater manufacturer's data, the head loss
across the water heater at 12 gpm is 5.5 feet water column.
Read down the first column of Figure 22, page 23 for the Ultra-155
until you find a flow rate just larger than the required 12 gpm.
You'll find a value of 13 gpm in the fourth row.
At 13 gpm, with an Ultra-155, the recommended pipe size is 1¼
inch. From the table, the head losses are:
H1 = 13.3 feet
H3 = 5.5 feet (from water heater manufacturer's data)
H = 13.3 + 3.9 + 5.5 = 22.7 feet.
total
22
— Boiler Manual
(continued)
— Refer to
H2 = 3.9 feet
The closest circulator selection (from Fig-
)
ure 23, page 23
at 22.7 feet head is either a Taco 0013 or a
B&G PL-36.
Note that, if the water heater were piped as in
Figure 21, then H1 would be 0, so total head loss
would be 14.7 feet (9.2 + 5.5). A Taco 0014 would
handle the load if piped this way.
See Figure 15 through Figure 19 for pip-
ing details not shown below. For DHW
piping as shown in Figure 16, use sizing
information in .
Figure 20
DHW piping direct-connected across
the boiler (used for Figure 15 through
Figure 19, but not for Figure 16)
Figure 21
DHW piping as a secondary circuit (used
for systems with DHW piping as shown
in Figure 16)
Part number 550-100-066/0608
that can deliver 12 gpm