Weil-McLain -105 Manual page 14

3
Install water piping
Sizing DHW system piping
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
Figure 5 DHW piping (see Table 2 for approxi-
mate head losses)
Figure 6 Pump curves for typical circulators
suggested for DHW loop
14
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GAS FIRED WATER BOILER SERIES
(continued)
3. Table 2 uses the available head from the circulators listed to help you select the
4. Procedure to select a circulator using Table 2:
Table 2
2 — Boiler Manual
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.
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.
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.
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, or
Bell & Gossett PL-36)
Part number 550-100-026/0404