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I'm stumped.

I installed a 3 section Peerless in a 1200 sq.ft. bungalow 5 years ago. Everything Beckett. One zone. Been purring like a kitten for 5 years. Annual check-up: clean as a whistle. Customer calls Sunday morning - no heat. AquaSmart says that the boiler temp is 190 degrees and that it is circulating. Temp/pressure gauge confirms temp and 15 psi. Supply and return are both 1.25". Supply piping is too hot to touch. Return piping is cold as you-know-what. Shut it off, isolate the circulator and pull it out of the housing. Turn on the switch: no motor. Replace the circulator, listen to it humming and go home happy. Check back an hour later and no change: supply hot, return cold. Come back Monday and start double-checking everything. Found no current on C1-C2. Replaced the AquaSmart. No change. I can hear the circulator purring. Use the Webstone stop-and-purge on the return and purge the system until I have hot at the return. Go away, come back - no change. Purge again. no change. Purge until I have cold water in both the supply and return. (I purge with the pressure reducing valve open and the drain valve throttled.) Still no change. I have not crawled under the house because the pressure gauge is working and shows no loss in pressure. What am I missing? I have been doing this type of work for 35 years so this is not my first rodeo. But, for once, this one has me stumped. Any suggestions?


  • Jamie Hall
    Jamie Hall Member Posts: 21,114
    Fools rush in where angels fear to tread... that's me. Having said that, I presume that when you inspected the circulator that the impellor is in good shape and spins with the motor? Because clearly it is not circulating, despite what it says -- since from your purging you know that water will flow through it if is pushed!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 13,442
    I assume the pump is pumping the right way (stupid question probably) no stuck check valves or flow checks? Can you put a gauge on each side of the pump?
  • Zman
    Zman Member Posts: 7,446
    I'll bet it is something obscure that will have you kicking yourself.
    I had one the other day where the webstone valve was mostly closed but the handle was showing it was open. It was just stripped out.
    I am thinking that 20 minutes or so sitting on a bucket and it will come to you.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 5,634
    I always ask the following question: " If you replace the X (Usually expensive part)" and it does the same thing, what will you check next? The answer is usually something very inexpensive like a fuse or something. I then say "check that first"

    First thing I would check is the power to the circulator motor. Can you see the coupling? or is it a wet-rotor pump? Since you can isolate it, you could take it off the flange and look to see it operate. (no parts involved yet). You can use a cut off extension cord and wire the pump hot to an outlet. If the impeller spins, then the circulator-pump is not the problem.

    Once you determine the pump is good, run the circulator pump hot from the extension cord to see if the water circulates. the heat should move thru the system and the return will get hot. if the return never gets hot, the system has an issue, like air, blockage, closed valve, insufficient pressure. If the water circulates, then the control is the issue.

    Now rewire back to the control and operate. If the control has power to C1 and C2 (check with meter) then the pump should operate. If the meter shows no power to C1 and C2 then find the problem in the control.

    Is the control set properly for the circulator to operate? If you have a control that has a reverse aquastat for the circulator, (this is used to make sure the boiler always has enough temperature for domestic hot water demand. the circ will stop if the water in the boiler drops below the minimum setting.) then it is possible to set the low limit too high and the circulator will never operate because the boiler temperature high limit shuts off the burner before the water gets hot enough to operate the circulator pump.

    Another thought is C1 has power but C2 has a bad connection on the printed circuit board. This would be called an "open common". The return path for the electricity is not complete. See if you have power between C1 and L2. If you have power, then solve the open common by using the L2 and not the C2

    These are random ramblings from an old fart sitting on @Zman's bucket in your basement
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Big Ed_4
    Big Ed_4 Member Posts: 2,239
    Do you have voltage at the Circulator ?
    I have enough experience to know , that I dont know it all
  • GrundfosHVACOEM
    GrundfosHVACOEM Member Posts: 2
    Can you put a gauge after the circulator and before ? Just to make sure the circulator is moving water if you can and you see not difference in pressure from inlet to discharge Houston you have a problem..