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primary loop circulator

See the video but basically the thermostats are calling for heat and I *think* the primary pump remains off. The white and black from the primary circ go to c1 and c2 on the 3250. Across c1 and c2 shows 0 volts even when heat is called. When the boiler goes to purge or fires then c1 and c2 show 120v. Am I doing this right?

Comments

  • unclejohn
    unclejohn Member Posts: 1,751
    When you read across a closed switch you read 0 volts. When the switch opens you will read 110 volts. Check for voltage at the pump on L1 & L2.
  • MikeBos
    MikeBos Member Posts: 17
    @unclejohn Tested and L1 and L2 and that always has 120v. C1 and C2 only have 120v when 3250 shows purge or the boiler is fired.
  • Sounds as though the 3250 only talks to the boiler and it should be talking to the Taco zone valve control. "End Switch" terminals on the zone valve control should be wired to the "T T" on the pump control.
    What's the brand name of the 3250?
    Often wrong, never in doubt.
  • MikeBos
    MikeBos Member Posts: 17
    @Alan (California Radiant) Forbes HydroStat 3250-plus I see the TT on the 3250 goes out to the SR503-4 switching relay isolated end switch then goes out to the RMB(unconfirmed terminal) then goes to the zvc404-4 zone valve control end switch where it terminates. Thanks folks for the help !
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 2,974
    edited November 2020
    So the end switches on the ZVC and SR controls will initialize both the RMB and the 3250.
    I think the problem is that each device (the RMB and 3250) have transformers and the way that you have daisy chained them together, they will compete.
    Often wrong, never in doubt.
  • MikeBos
    MikeBos Member Posts: 17
    edited November 2020
    Installed 4 ago years by professionals. Recently (heating season just started in MA) I noticed when radiant loop is calling that the RMB mix supply temp does not rapidly go toward the target temp and sometimes even goes the opposite direction. At the moment target is 114f . I just watched the source temp start at 103 and go down to 98f then proceed to go to 122f. This got me wondering if the primary circ was even pumping. Very confusing.
  • MikeBos
    MikeBos Member Posts: 17
    Had the oil guy over to take a look. He says it working as designed. I don't think so. I've read elsewhere that the primary circ should be running when high or low temp are calling. Contacted Taco but no word back yet.
  • Jamie Hall
    Jamie Hall Member Posts: 17,162
    MikeBos said:

    Had the oil guy over to take a look. He says it working as designed. I don't think so. I've read elsewhere that the primary circ should be running when high or low temp are calling. Contacted Taco but no word back yet.

    Not necessarily. If by primary, you mean the boiler loop, it should run when the boiler is running -- whatever controls the boiler.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Robert_25
    Robert_25 Member Posts: 365
    https://hydrolevel.com/wp-content/uploads/2019/11/HydroStat-3250-Plus-Instructions-web-111919.pdf

    See page 9 in the attached.  There are some options in the menu that control how the circulator relay behaves.
  • MikeBos
    MikeBos Member Posts: 17
    The primary is the high temp loop and when needed it fires the boiler and the primary circ. Based of a low limit of 160f .
    My ZC/ZR are not wired but thanks. I checked and it is in TT mode 'a'
    My main question is based on my primary/secondary setup should the primary circ be running when there is a call for heat regardless of high temp or low temp ( upstairs baseboard / downstairs infloor radiant )
  • Robert_25
    Robert_25 Member Posts: 365
    Yes, the circulator should run on a heat call from either zone - but if the boiler temperature drops below the low limit during heat call, the circulator will stop until the boiler recovers.
  • MikeBos
    MikeBos Member Posts: 17
    Found the below paragraph in the docs. I have the RMB in 'enable' mode. Maybe I'm seeing this logic where the contacts call only like described in the doc? BTW when I jump the boiler contact(in the mixer),it kicks on the primary circulator. When I jump the end switch in the valve controller for the radiant it kicks on the constant pump that is in the mixer. I think maybe since I have an outdoor thermo that adjusts to the max mixing target temp as the outdoor temp drops. Maybe the system just has not needed to exceed the 25% variable. I could prob test further by turning the target temp up much higher requiring that the mixer variable pump run over 25%. I'll try that next. Unfortunately there is a test mode that runs the variable up to 100% but this did not close the switch for the primary circ but not sure it's part of the test?

    FROM THE MANUAL:
    When the RMC “Enables” the boiler, the RMC opens and closes the boiler contact based on the output of the variable speed injectionpump. The actual temperature and cycling of the boiler is then determined by other controls or the aquastats on the boiler itself.When operating in the boiler enable mode, the boiler contact turns on once the variable speed output exceeds 25%. The boilercontact shuts off if the output of the variable speed drops below 5% for more than three minutes or if the demand is removed from theRMC.
  • MikeBos
    MikeBos Member Posts: 17
    And again from the docs my sensor should have been on the boiler return when in 'enable' . So I suppose I'll see the variable circ behave differently based on that sensor move.