Weil-McLain ECO 70 Manual page 53

TM -
G
AS FIRED WATER BOILER
Multiple boiler installations
DHW tank piping with multiple ECO
boilers
DHW direct connection—single tank
1. If BTUH output of a single boiler is sufficient for the
DHW tank/demand, pipe the indirect water heater to
the last boiler in the firing sequence. This will allow the
previous boilers to continue space heating while the last
boiler delivers DHW priority.
2. Pipe from the near-boiler piping to the DHW tank's
boiler connections as shown in Figure 50, page 47.
3. Connect the DHW tank aquastat directly to the DHW
input on the last boiler in the sequence.
Piping layout—typical piping for multiple boilers (4-boiler system shown) with DHW storage heaters grouped
as zone in secondary loop off primary system loop
Part number 550-142-122/0513
— Boiler Manual
(continued)
When using a multiple-boiler control with lead boiler
rotation, it is recommended that the boiler connected to
the DHW tank is always set as the last boiler to operate
in the sequence so that space heat can be maintained
during times of DHW demand.
DHW tanks as zone—multiple tanks
1. If using multiple DHW tanks or multiple banks of tanks, pipe the
tanks to the primary system loop with a secondary connection as
shown in Figure 58.
2. DHW tanks are zoned with circulators as shown.
3. DHW circulators should be controlled with a Weil-McLain
WMCR zone controller.
4. If DHW priority is required, use separate zone controllers for
DHW and space heating. Connect the isolation switch output
of the DHW zone controller to the DHW input of the multiple
boiler control (Weil-McLain BCP, BMC, or BSC).
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