Weil-McLain ULTRA 80 EN - Manual (Page 14)

Part number 550-101-233/0903
GAS
-
FIRED WATER BOILER
— Boiler Manual
14
Install water piping
(continued)
3
Figure 6 Pump curves for typical circulators
suggested for DHW loop
Table 2 Pipe sizing and head losses for DHW applications
(H1=boiler head loss; H2=piping head loss; H3=maximum
allowable head loss through water heater based on available head
of circulator chosen; i.e., Taco 007, 0011, 0012, 0013 or 0014, Bell
or Gossett PL-36)
Figure 5 DHW piping (see Table 2 for approxi-
mate head losses)
Sizing DHW system piping
circulators (Taco 007, 0011, 0012, 0013, 0014, B&G PL-36 or equivalent). Use
these curves along with boiler pressure drop data from Table 2 to size the DHW
piping and circulator. Or you can use Table 2 for a quick-selection method.
3. Table 2 uses the available head from the circulators listed to help you select the
right circulator.
a. See Figure 5.
b. H1 is the head loss across the boiler.
c. H2 is the head loss across the DHW piping.
d. H3: Table 2 subtracts H1 and H2 from the available head of the circulator. This
gives the maximum value for H3, head loss across the water heater.
4. Procedure to select a circulator using Table 2:
Step 1: From the water heater manufacturer’s data, find:
• Required boiler water flow rate, GPM, at 180°F.
• Pressure drop across the water heater at this flow rate, in feet water column.
Step 2: Find your boiler model in Table 2. Select a flow rate in column 1 just
larger than the required flow rate from step 1.
Step 3: The value in column H3 must be larger than the water heater pressure
drop from step 1.
When using the boiler for dedicated DHW
applications, use the circulator supplied with
the boiler (007 for Ultra-80/105; 0011 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. Figure 5 shows recommended DHW piping, as shown in
Figures 7 through 10, pages 15 – 18. All show direct
connection of the DHW piping to the boiler because the
boiler circulator shuts down during DHW operation.
2. Figure 6 shows the pump curves for suggested DHW