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Relay panel for taco circulators not working

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Hi all.

I just switched my thermostats (2 different zones) to heat and no circulation in my hot water baseboards.

The grundfos relay panel has no power.  I swapped the 250 main fuse and it flashed when I turned a knob the power then appears to have blown the fuse again.

I saw that on my genysis burner control the looped thermostat wire on the top was disconnected on one side so I reconnected it now, but no luck.

I'm thinking perhaps the burner genysis 7505 is shot and maybe I should swap it out?  Am I going in the right direction?  Any other ideas?

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,433
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    A fuse which blows immediately is a short somewhere. Before you start banging away with the parts cannon, start by checking all the wiring and all the connections for being as they should be.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Lucent100EdTheHeaterMan
  • Joe Mattiello
    Joe Mattiello Member Posts: 707
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    If it’s a control pañal, take everything off, and methodically put wiring back on control until you’ve identified the problem. 
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
    EdTheHeaterMan
  • Lucent100
    Lucent100 Member Posts: 5
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    The bridge wire for the thermostat was disconnected on one terminal on the genysis 7505 I found.

    I hooked it back up but no good.  Would that have fried the genysis 7505? 
  • Ironman
    Ironman Member Posts: 7,379
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    Lucent100 said:
    The bridge wire for the thermostat was disconnected on one terminal on the genysis 7505 I found.

    I hooked it back up but no good.  Would that have fried the genysis 7505? 
    Not if you connected it between TT.

    I realize that you may not be a pro and that you may be giving the best description that you can, but it’s just too vague.

    A pro would be confirming that the wiring is correct and then using his meter to diagnose. Without pictures of what you have, and then readings taken step by step with a meter, it’s gonna be difficult to solve your problem.

    What Joe Mattiello said might be your best DIY shot.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Lucent100EdTheHeaterManSTEVEusaPA
  • Lucent100
    Lucent100 Member Posts: 5
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    The wire came off the TR connection on the front right of the genisys 7505 control.  I hooked it back up and restarted the system.

    Here are a few photos.  Nothing else was touched inside.  The fuse in the grundfos panel mounted on the side of the side of the boiler keeps blowing.


  • Jamie Hall
    Jamie Hall Member Posts: 23,433
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    A fuse which blows immediately is a short somewhere. Before you start banging away with the parts cannon, start by checking all the wiring and all the connections for being as they should be.

    Let's try this again
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    mattmia2Ironman
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,068
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    I see 4 fuses here. which fuse is the problem fuse?

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Lucent100
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,068
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    I wonder if there is a shorted wire under one of those connectors. Many times the electrician forgets to install the anti-short bushing and finds there is a broken section of insulation under that clamp.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Lucent100
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    I.know it’s MC, but none of that line voltage wiring should be touching the very hot boiler door.
    And that loop from the E switch, under the burner and up and around to the aquastat looks ridiculous to me, as does the giant loop from the switch to the zone panel.
    As to your problem, as @Ironman stated, you just have to work the meter, and follow the path of what is supposed to happen.
    The jumper on your primary control has no voltage, it’s just a switch. If you have 120 volts going to the primary from L1, and 120v from your high limit to the primary, then your burner will fire if T-T are jumpered.

    There was an error rendering this rich post.

    Lucent100Ironman
  • Lucent100
    Lucent100 Member Posts: 5
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    There are 5 fuses and it's the main line in on the bottom right that blows.  Look all the way down in the lower right where the power comes in.
  • 109A_5
    109A_5 Member Posts: 1,387
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    Hello @Lucent100,

    Since the fuse that is blowing is 250 mA or 0.25 Amps or 1/4 Amps, the pump loads are probably not the problem. Since at 250 mA it is not a 'Main Fuse' that supplies all loads connected to that box. It appears that fuse only supplies power to the transformer. The output of the transformer (24 VAC) supplies power to the thermostats and the coils of the relays, any internal electronic logic and the indicator LEDs.

    Not sure what this means in your original post " I swapped the 250 main fuse and it flashed when I turned a knob the power then appears to have blown the fuse again. " What knob ? A thermostat ?

    If only one thermostat activation blows the fuse the White wire from that thermostat wire may be compromised to ground (assuming the 'Common' side of the 24 VAC transformer is grounded somewhere). The other thing is one of the flyback diodes across a relay coil is defective overloading the circuit when the circuit attempts to energize the relay coil or a relay coil is defective.

    So since only that fuse is blowing the most likely things is thermostat wiring (the White wire) or a defect on the circuit board. All other connections to that box are isolated by a relay (Main XX and H, N for the pumps (switched Hot)). I don't believe the Genisys 7505 control has anything to do with this issue.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    Ironman
  • Ironman
    Ironman Member Posts: 7,379
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    Here would be a good place to start looking for the short:


    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    mattmia2STEVEusaPA
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,068
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    Based on @109A_5's explanation above, you will want to remove the thermostat wires from the UPZCP-6 relay, install a new fuse and power on the system. If the fuse does not fail and everything else is connected properly then take a small piece of wire to use as a jumper. Turn off the power and connect the wire from R to W on one of the zones that you are using. Click on files below for illustrations

    Then turn on the power and see if the fuse blows. if not, then power off and change the jumper to the other zone. power on and see if the fuse blows. If the fuse blows on this test then the UPZCP-6 control may be defective. You may try using a different zone to power up that circulator and see if the problem is only on the one that blows the fuse. For example if zone 2 blows the fuse then place the circulator pump wires on zone 4 and the jumper on zone 4. if the fues does not blow then you may be able to use that control as long as you never need to use zone two

    IF the fuse does not blow on that test then power off and remove the jumper.
    Connect one of the thermostat wires normally. Power up the system and make the thermostat call for heat asn see if the fuse blows. If yes then you have a problem with that thermostat wire. Run a new wire from the thermostat to the UPZCP-6 control.

    If the fuse does not blow and that zone runs properly then connect the other zone thermostat wires normally and do the same test. This is called a process of elimination. once you have discovered what exact change you made that causes the failure, then you can look closely at that problem.

    Let us know how you make out.

    Yours truly,
    Mr. Ed

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

    Lucent100
  • archibald tuttle
    archibald tuttle Member Posts: 1,085
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    @EdTheHeaterMan really nice explanation ed
    EdTheHeaterManLucent100
  • mattmia2
    mattmia2 Member Posts: 9,741
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    Ironman said:

    Here would be a good place to start looking for the short:


    I had that happen with 12-3 romex. It was rather spectacular.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    But why keep blowing the fuse? Put a pro short tool or equivalent in line until you find the low voltage short

    There was an error rendering this rich post.

  • mattmia2
    mattmia2 Member Posts: 9,741
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    or a 24v or so lamp to limit the current.
  • 109A_5
    109A_5 Member Posts: 1,387
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    mattmia2 said:

    or a 24v or so lamp to limit the current.

    If the fuse is on the 120 Volt side of the transformer you want to use a 120VAC lamp maybe 15 or 25 Watt incandescent type only in place of the fuse. If the lamp remains dim things are normal, if lamp lights up bright the transformer is overloaded.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • 109A_5
    109A_5 Member Posts: 1,387
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    But why keep blowing the fuse? Put a pro short tool or equivalent in line until you find the low voltage short

    Do they make a 250 mA or 0.25 Amp or 1/4 Amp "pro short tool" ? I thought they were 3 Amps or more and limited to 24 VAC use. Looks to me like the fuse is on the 120 VAC (transformer primary) side. A proper sized incandescent lamp is less expensive (if you can find them) and automatically self resetting. Maybe a refrigerator lamp in this case.

    A 3 Amps or more "pro short tool" on the primary side may let the transformer burn up in this case. Also in this case, no easy place to put it on the secondary side, since the transformer is soldered to the circuit board and the over-Current defect may actually be on the circuit board.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Lucent100
    Lucent100 Member Posts: 5
    edited September 2023
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    Thanks all.  Seems like it's the relay board itself.  I ordered a new one.  Maybe a lightning strike during the summer?  Maybe just a bad board, who knows.

    I turned the boiler off last night, hooked up the 120 line straight to my downstairs circulator and ran it for a bit to at least take the chill out of the house.

    I learned a ton about the boiler wiring through this process, so thanks a million again.

    I am looking to buy more 250 mA fuses in case again, but they are not easy to find apparently.  I tried the part number through the grundfos manual and they are saying it discontinued.  If anyone knows where to get these little fuses it is appreciated 
  • 109A_5
    109A_5 Member Posts: 1,387
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    You may have to measure the physical size and maybe get all the numbers / letters from it to match it up. Maybe 5 x 20 mm size not sure, may be a bit bigger.

    Digikey.com, Mouser.com, maybe ebay.com or amazon.com.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    Lucent100