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Option #1 (DEFAULT): System Pump Used for CH Only, DHW Priority Pumping – An example of this system is shown
in Figure 12.2, as well as in Figures 9.3A and 9.3B. When this option is selected, the system operates as follows:
a) Boiler pump runs whenever there is a demand
b) DHW pump circulates water through the portion of the system loop where the boiler loop is connected (i.e. the closely
spaced tees for the boiler loop).
c) The system pump is used only to circulate water through the heating (CH) zone/s.
d) The system pump is not allowed to operate while the boiler is responding to a call for DHW (this strategy permits the
entire output of the boiler to be directed to the indirect water heater and in some cases is also needed to protect some
types of radiation from excessive temperatures).
Option #2: System Pump Used for CH Only, No DHW Priority Pumping – An example of this system is shown in Figure
12.2, as well as in Figures 9.3A and 9.3B. The only difference between Option #2 and Option #1 is that Option #2 permits the
system circulator to operate at the same time as the DHW pump when there is a call for both heat and DHW.
Option #3: System Pump Used for Both CH and DHW, No DHW Priority Pumping – An example of this system is
shown in Figure 12.3, When this option is selected, the system operates as follows:
a) Boiler pump runs whenever there is a demand.
b) DHW circulates water only as far as a set of closely spaced tees in the system loop.
c) The system pump is required to circulate water for either a space heating or DHW demand.
d) A fourth pump (controlled by an installer supplied relay) is required to circulate water through the radiation.
TochangetheDHWconguration,pressthelargebuttoncontainingthedescriptionrepeatedlyuntilthedesireddescription
isreached.Whentheselectionischanged,thisbuttonwillash.Whenthedesiredcongurationisreached,pressSETto
selectit.Whenthischangeisacceptedbythecontrol,thebuttonwillstopashing.PressEXITtoReturntotheConguration
Menu.
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