Bradford-White Corp Copper Brute II Hydronic Boiler Manual De Usuario

Page 51

a load distribution problem. See 

Section 6.3

 regarding 

controller setup. Contact your Bradford White 

representative to discuss possible remedies.

Short cycling will generally occur only in 

combination space heating and water heating 
applications when the water heater is operating in the 

space-heating mode. Because the Copper Brute II is a 

stage-fired water heater and its input will reduce when 
there is a reduction in heating load, short cycling is 

greatly reduced. If the heating load drops below the 

minimum input of the water heater for an extended 
period, the water heater will have a tendency to short 

cycle. If short cycling is frequently experienced, 
regardless of the control’s attempt to limit it, the 

heating load should be redistributed to control it. See 

Section 6.3

 regarding controller setup.

If short cycling occurs in a water heater 

application, it is probably caused by undersized 
piping between the water heater and the storage tank 
or by some other factor that restricts proper water 

flow through the water heater. The cause should be 

determined and corrected. 

Appliances operating with an improper air/

fuel ratio are very inefficient and consequently, have 

very high gas consumption. Because efficiency is 
high when the CO

2

 is high (or O

2

 is low), appliances 

operating with low CO

2

or high O

2

 (especially LP 

appliances) consume more gas. Adjust the CO

2

 or O

2

 

for optimum efficiency. If no combustion analyzing 
equipment (CO

2

 or O

2

) is available then a proper 

adjustment of the air/fuel ratio (CO

2

 or O

2

) cannot be 

accomplished. However, by briefly sniffing the flue 
gases it is possible to determine if the CO

2

 or O

2

 is 

within the proper range. No significant flue gas odor 

should be detected when combustion is proper. A 
strong piercing smell indicates poor combustion and 

generally a lean mixture - low CO

2

 or high O

2 

. The 

CO

2

 should be 8% at high fire. To check the CO

2

, first 

verify that the supply gas pressure is within 5" to 13" 

w.c. (1.2 to 3.2 kPa) With the Copper Brute II running 

with all stages firing, set the air box pressure to 1.5" 

w.c. (0.37 kPa) (as a starting point), by adjusting the 

air shutter(s) at the bottom of the fan(s). Check the 
CO

2

, and adjust the air shutters if further adjustment 

to the CO

2

 is needed. Sizes 1250 to 2000 have two 

blowers and two air chambers (boxes). The pressure of 

each air box must be equal when the final adjustment 

is made.

There are many causes of lockouts. The three 

most common causes are: (1) inadequate gas supply, 

(2) poor combustion, (3) ignitor failure.

1.  Inadequate gas supply: Before proceeding, ensure 

that the gas supply has not been shutoff or the LP 

tank (LP boilers) is not empty. Then, restart the 

boiler and observe the operational cycle. After 

a 15-second fan pre-purge, the ignitor will heat 

up for 20 seconds, and then the unit will light. 
If it does not, check the gas supply pressure to 
the appliance, after resetting the appliance and 

attempting another start-up. The gas pressure 

to the appliance must be above 5" w.c. (1.2kPa) 

throughout the entire start-up cycle. If it is not, 
correct the supply problem (check gas valves or 

supply piping). If the supply pressure is adequate, 

consult the factory for assistance.

2.  Poor Combustion: Poor combustion should 

be suspected if there is a strong flue gas odor. 

The odor may result from an improper gas/air 
ratio (high or low O

2

 or CO

2

). Copper Brute II 

appliances operate best with 45% excess air (8% 
CO

2

 on natural gas, 9.2% CO

2

 on LP). Check the 

CO

2

 of the appliance and adjust if necessary.

3.  Ignitor failure: If the boiler goes through a 

normal start cycle but combustion does not 

occur, ignitor failure should be suspected. Check 
the ignitor by unplugging the ignitor plug and 

measuring the ignitor resistance. It should be 

50-80 ohms. If the resistance is not 50-80 ohms, 

replace the ignitor. If the resistance is correct, 

reset the boiler and check for 120 VAC at the 

ignitor plug during the start cycle. If there is no 
voltage, replace the faulty ignitor wire harness or 

the ignition control.

A defective burner can cause a delayed ignition. 

If the gas supply pressure is proper and the gas 
valves are functioning properly, then burners should 

be inspected. There should be no distortion or 
perforations in the burners outside of the active burner 

port area. Replace if indicated.

Because the Copper Brute II is a stage-fired 

boiler, and its input will decrease when there is a 
reduction in heating load, short cycling is greatly 

reduced. If the heating load drops below the minimum 

input of the boiler for an extended period, the boiler 

will have a tendency to short cycle. This can be a 
symptom of improper control strategy or setpoints, or