Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

No external pump output

Bob6 Member Posts: 5
We have a 2 year old Rheem Prestige combi boiler.  Yesterday the output to the external circulation pump stopped working.  The panel screen shows that the pump is to be turned on but zero voltage at the terminals.  The rest of the system is working fine, no blown fuses, power transformer is fine, just no voltage the the zone pump.  I ordered a replacement circuit board, but don't see any components on it like a relay that would be used to turn on a pump.  Any ideas?



  • 109A_5
    109A_5 Member Posts: 826
    Hello @Bob6,

    No model number so this is a just guess as to the manual. Looks like there are relays or maybe they are actually Triacs (a solid state AC switch). Failed solder joint ? Pin fitment at a connector ?

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Bob6
    Bob6 Member Posts: 5
    Hello.  I completely missed that schematic in the manual.  It's a Rheem Prestige model RCBH199DVLP.  The schematic you posted looks to be correct.  I'll take a look at the solder joints.  Has to be something simple.  It has been running fine for 2 years and zip, no external pump.  

    Thanks for your help,

    EBEBRATT-Ed Member Posts: 13,760

    You might check the pump motor to see if it is ok. Disconnect it and temp wire it to a source of power. You don't want to smoke a new circuit board due to a defective pump.
  • Bob6
    Bob6 Member Posts: 5
    Already did that.  Motor is fine.  To be on the safe side I'm going to add in a 1 amp inline fuse into the pump wiring before I swap out the board when it comes.  The unit is limited to 2 amp pump max.  The pump is .71 amps.  Fuses are cheap, boards not so much.  Personally I think your thoughts on bad solder joint is probably the most logical cause.  Seen that before on circuit boards on various cars I've owned in the past.  
  • Jamie Hall
    Jamie Hall Member Posts: 21,517
    Before you swap out the boards, check all the connections -- particularly plugs and sockets. You doubtless know that anyway, since you mention cars... I'd say that 90% of the failures on modern cars are bad power, bad grounds, or crusty sockets and plugs.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Bob6
    Bob6 Member Posts: 5
    Will do.
  • Bob6
    Bob6 Member Posts: 5
    Thanks everyone.  It's really helpful getting feedback from others.  Most people nowadays don't know jack on equipment and your comments have helped a lot.  Hope I can return the favor in the future.