Monitor Screens; Output Control And Burner Sequence - Lochinvar TTW Series Installation, Commissioning And Maintenance Instructions

When cascade connection is programmed correctly, the water heater display will show the following.
Explanation "Cascade communication indicator"
NO CASCADE COMMUNICATION
>
Always showing the fixed ">>>"
CORRECT CASCADE COMMUNICATION
>
Showing alternating no.1 & no.2 with 1-second interval.
17.3.2

MONITOR SCREENS

To obtain cascade information, see 16.4.
17.3.3

OUTPUT CONTROL AND BURNER SEQUENCE

The total cascade set-up will act as one single big water heater, switching on- and off burners, depending on the total load necessary to adjust
and keep the flow temperature at the calculated value.
When the heat demand rises, more burners are switched on, and when heat demand falls, one or more burners will be switched off. The burner
that was switched on last will be switched off first, see table below.
To distribute operating hours equally over all burners, the working sequence of the burners will change every hour.
Hour Switching ON sequence
Master – Slave 1 – Slave 2 – Slave 3 – Slave 4 – Slave
X
5 – Slave 6 – Slave 7
Slave 7 – Master – Slave 1 – Slave 2 – Slave 3 – Slave
X+2
4 – Slave 5 – Slave 6
Slave 6 – Slave 7 – Master – Slave 1 – Slave 2 – Slave
X+4
3 – Slave 4 – Slave 5
Slave 5 – Slave 6 – Slave 7 – Master – Slave 1 – Slave
X+6
2 – Slave 3 – Slave 4
........... .........................................................
Table: burner sequence example of a four water heater cascade (four TTW water heaters = eight burners).
In this table a total of four water heaters (one master burner, seven slaves) is mentioned as an example, in practice the maximum number in a
cascade, without extra (external) control, is six water heaters (= twelve burners).
> > no.1
> no.1
no.2
>
Switching OFF sequence
Slave 7 – Slave 6 – Slave 5 – Slave 4 – Slave 3 – Slave
2 – Slave 1 – Master
Slave 6 – Slave 5 – Slave 4 – Slave 3 – Slave 2 – Slave
1 – Master – Slave 7
Slave 5 – Slave 4 – Slave 3 – Slave 2 – Slave 1 – Master
– Slave 7 – Slave 6
Slave 4 – Slave 3 – Slave 2 – Slave 1 –
Slave 7 – Slave 6 – Slave 5
.........................................................
Master –
86