Bradford-White Corp BWCV User Manual

Internet Version for Reference Only

Page 26

Copper Brute II

Page 27

Minimum Off Time (MIN OFF) – The 

minimum off time is the minimum amount time that a 

stage must be off before it is allowed to turn on. Once 

a stage turns off, it cannot turn on until a minimum 

off time elapses. The minimum off time is adjustable 

through the MIN OFF setting in the Adjust menu.

– PID staging allows the control to determine when 

the next stage is required to turn on. The control 

automatically determines the settings that are manually 

selected in proportional staging mode. After each stage 

is turned on in the firing sequence, the control waits a 

minimum amount of time before turning on the next 

stage. After the minimum time delay between stages 

has expired, the control examines the control error to 

determine when the next stage is to fire. The control 

error is determined using PID logic.

Proportional compares the actual operating 

sensor temperature to the heater target temperature. 

The colder the temperature, the sooner the next stage 

is turned on.

Integral compares the actual operating sensor 

temperature to the heater target temperature over a 

period of time.

Derivative determines how fast or slow the 

operating sensor temperature is changing. If the 

temperature is increasing slowly, the next stage is 

turned on sooner. If the temperature is increasing 

quickly, the next stage is turned on later, if at all.

Boiler Mass (BOIL MASS) – The boiler mass 

setting allows the installer to adjust the control to the 

thermal mass of different types of heat sources used. 

The boiler mass setting automatically determines the 

interstage differential, interstage delay on, interstage 

delay off, minimum on time and minimum off time of 

the stages when PID staging is used. A higher thermal 

mass setting provides slower staging, while a lower 

thermal mass setting provides faster staging. Copper 

Brute II water heaters are low-mass appliances, and 

therefore, should be used with the lower thermal mass 

setting. Set BOIL MASS to “1”.

The minimum boiler setting (BOIL MIN) is the 

lowest water temperature that the control is allowed 

to use as a target temperature. During mild conditions, 

if the control calculates a target temperature that is 

below this setting, the target temperature is adjusted to 

at least the minimum setting. During this condition, if 

the unit is operating, the MIN segment turns on in the 

LCD while the target temperature or operating sensor 

temperature is viewed. For Copper Brute II units, this 

must be set no lower than 120°F (49°C) to protect the 

unit from condensing on the heat exchanger (see Figure 

14).

Differential has an abbreviated name of DIFF. An 

on/off heat source must be operated with a differential 

in order to prevent short cycling. The differential 

is divided around the boiler target temperature (see 

Figure 13). The first stage contact will close when the 

water temperature at the operating sensor is one-half of 

the differential setting below the target temperature. It 

will open when the water temperature at the operating 

sensor is one-half of the differential setting above the 

target temperature. The remaining stages will operate 

sequentially, based on the staging mode selected.

The Copper Brute II 500 and 750 control 

operates two stages. The Copper Brute II 1000 control 

operates three stages. The Copper Brute II control for 

models 1250-2000 operates four stages. The method 

of staging used by the control is either P (proportional) 

or PID (proportional & integral & derivative), and 

is selected using the STGMODE item in the Adjust 

menu.

Proportional (P) – Proportional staging, also 

known as step staging, is based on manually adjusted 

settings which determine when the next stage is 

required to turn on. These manual settings are based 

on temperature and time. The interstage differential 

sets the temperature drop at which the next stage turns 

on. However, in order for a stage to fire, the interstage 

delay on and minimum off times must first elapse.

Interstage Differential (STG DIFF) – The 

interstage differential is the temperature drop at which 

the next stage will turn on. Once a stage turns on, the 

next stage cannot turn on until the temperature drops 

the interstage differential below the temperature at 

which the previous stage turned on. The interstage 

differential is adjustable through the STG DIFF setting 

in the Adjust menu. See Figure 13.

Interstage Delay On (ON DLY) – The 

interstage delay on is the amount of time that must 

elapse before turning on the next stage. Once a stage 

turns on, the next stage cannot turn on until the 

interstage delay on time elapses. The interstage delay 

on is adjustable through the ON DLY setting in the 

Adjust menu.

Interstage Delay Off (OFF DLY) – The 

interstage delay off is the amount of time that must 

elapse before turning off the next stage. Once a stage 

turns off, the next stage cannot turn off until the 

interstage delay off time elapses. The interstage delay 

off is adjustable through the OFF DLY setting in the 

Adjust menu.

Minimum On Time (MIN ON) – The minimum 

on time is the minimum amount time that a stage must 

be on before it is allowed to turn off. Once a stage 

turns on, it cannot turn off until a minimum on time 

elapses. The minimum on time is adjustable through 

the MIN ON setting in the Adjust menu.