Crown Boiler 24-04 Manual De Usuario

33

1.  HOT WATER HEATING - This boiler must be 

installed in strict accordance to the instructions 

found in this installation manual.  Deviations 

from these installation instructions may void 

manufacturer’s warranty.   See warning below 

to determine the use of the RTC.  A Return 

Temperature Control (RTC) may be provided to 

protect the boiler from thermal shock and sustained 

condensing operation.  In addition, a properly 

selected boiler circulator and diverting valve, along 

with the return sensor, must be installed when using 

the RTC.  A number of typical Crown applications 

have been added to the appendix (Appendix A).  

Select the appropriate application before proceeding.
a.  Parallel Piping Systems – An existing parallel 

piping system may be used, provided the return 

water is not below 135°F for prolonged periods 

of time, and the return water temperature is 

not more than 40°F less than the idle boiler 

temperature (see warning below).  A flow 

analysis should be performed to determine the 

flow through the boiler when the minimum (and 

smallest) and maximum number of zones are 

activated.  A sufficient flow through the boiler 

should be maintained to assure a maximum of 

40°F difference between the boiler supply and 

return.

  If the conditions above cannot be met, then 

parallel piping systems must be converted to a 

primary/secondary arrangement, de-coupling 

the system pump from the boiler loop.  The 

system pump cannot influence the flow through 

the boiler(s) in a primary/secondary piping 

arrangement.  The concept must be for the boiler 

loop to inject heat into a primary loop, provided 

the return water into the boiler is at least 135°F.  

  A by-pass containing two closely spaced tees 

must be installed to de-couple the boiler loop 

from the primary loop (see Figure 30).  Care 

must be taken to avoid dead heading the 

system pump.  Conversions should be reviewed 

and approved by a Consulting Engineer or 

other qualified professional to avoid system 

deficiencies.  

b.  Primary/Secondary Piping – Boiler(s) must 

be installed into a heating system that is 

(are) designed as a primary/secondary piping 

arrangement when the flow through the boiler 

cannot be maintained to provide a 20°F - 40°F 

difference between the boiler supply and 

return.    When using an RTC, the boiler loop 

contains a boiler, boiler circulator and diverting 

valve, along with the return temperature control 

(RTC) and return sensor.  The diverting valve 

consists of a 3-way valve, positioned through 

the use of an electronic actuator.  The boiler loop 

injects heat into the primary loop, provided the 

temperature of the boiler return water is greater 

than 135°F.  If the temperature is below 135°F, 

the diverting valve closes, recirculating the 

boiler water until it has heated above the 135°F 

minimum limit.  The supply and return of the 

boiler loop is connected to the primary loop 

through the use of two closely spaced “Tees”, at 

a maximum branch centerline distance of 4 times 

the primary loop diameter (4 x D Max.)  The 

RTC provides a signal to the actuator based on 

the absolute water temperature and the rate of 

change in water temperature.   

c.  Multiple Boilers – Multiple boilers are installed 

the same as single boiler installations.  Each 

boiler loop will contain it’s own boiler circulator, 

diverting valve, RTC and return sensor (see 

Appendix A).  Commonly available sequencers 

can be used in conjunction with the Return 

Temperature Control by energizing the control’s 

heat demand circuit.  The outdoor reset feature 

of the sequencer must be used in multiple 

boiler installations.  The outdoor reset feature