15
WHL-032 REV. 6.2.16
Cascade Operation
- When multiple boilers are installed, they can be wired together in a cascaded system. A maximum of twenty (20)
boilers can be controlled from a single boiler control. In Cascaded Systems, one boiler
is designated as the “Master” and the other
boilers are designed as “Followers”.
When the Master boiler receives a call for heat from a room thermostat, the control will determine the set point. If Outdoor Reset or 0-
10V is used, connect the outdoor sensor or 0-10V to the low voltage terminals provided on the Master boiler. The set point will be
determined based on the programmed reset curve parameters. If Outdoor Reset or 0-10V is not used, a fixed temperature set point can
be programmed into the control.
NOTE:
This setpoint is for the system sensor.
If the water temperature at the system sensor is less than the set point
– the cascade system temperature differential (32:Cd), then the
control will initiate a call for heat. The Master boiler will energize the lead boiler in the cascade system. In a new system start-up this will
be the Master boiler.
The boiler will fire at its ignition speed and then modulate its firing rate to maintain the set point. If the first boiler reaches 80% of its
firing rate, the Master will modulate down and split the load in half. At this point, the Master will fire the second boiler in the system. If
there are more than two boilers in the system, the same principle will be applied. Once the Master reaches 80% of the capacity, it will
modulate down and split the total amount of load by the number of unit in operation.
If the set point still cannot be met, the Master will continue firing more Followers until either the heat demand is met or all boilers on the
Cascade are firing. As the heat demand decreases, all boilers on will modulate down according to the heating load. The first boiler to
modulate down to 40% will shut off. The same principle will be applied to the remaining boilers in operation until the heating demand or
system sensor is satisfied. When the system sensor is satisfied, the boilers will turn off. However, the system pump will continue to
operate until the heating demand is satisfied.
PART 4 – PREPARE BOILER LOCATION
A. UNCRATING THE BOILER
UNCRATING BOILER
– Any claims for damage or shortage in shipment must be filed immediately against the transportation company
by the consignee.
Cold weather handling
– If boiler has been stored in a very cold location (below 0
o
F) before installation, handle with care until the plastic
components come to room temperature.
Remove all sides of the shipping crate to allow the boiler to be lifted into its installation location.
Carefully consider installation when determining boiler location. Please read the entire manual before attempting installation. Failure to
properly take factors such as boiler venting, piping, condensate removal, and wiring into account before installation could result in
wasted time, money, and possible property damage and personal injury.
B. BEFORE LOCATING THE BOILER
Incorrect ambient conditions can lead to damage to the heating system and put safe operation at risk. Ensure that the boiler installation
location adheres to the information included in this manual. Failure to do so could result in property damage, serious personal injury, or
death.
Failure of boiler or components due to incorrect operating conditions IS NOT covered by product warranty.
