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Slow-blo fuse keeps blowing every few days for Circulator Pump

SuburbanHomeOwnerSuburbanHomeOwner Posts: 18Member
edited December 2 in THE MAIN WALL
Hi all. Thank you for this great resource. I just joined yesterday and have already learned so much.

Have a zone control board that keeps blowing a fuse every few days that provides heat to my kids' bedrooms. The weather is getting cold and we will be going away and i'm afraid of pipes bursting when I'm not around to change fuses (yes, I know this isn't addressing the root cause, only the symptom and probably made the situation worse).

The wiring for this particular fuse runs to a B&G series 100 circulator pump, on a gas fired furnace from 1998. We have forced hot air.

This same fuse issue was happening intermittently on my old Taco SR506 6 zone switching relay. Thinking it was an issue with the board last year, I personally replaced it with a newer version of the same board. However, the same thing is happening again every week or so during this heating season. I wired everything up exactly as it was before. The system uses a 6 amp slow-blo fuse. Each time I replace the fuse, I have heat again for another week.

At the start of this heating season, the fuse was blowing immediately and after going through a half dozen fuses, I couldn't figure it out and the kids slept in our bedroom. The person who performed the tune-up on our heating system 2 weeks later told me that the issue was related to a broken coupler and quoted me $ for a replacement! I found the part at Home Depot for $18 and replaced it in 15 mins! :smile:

However, the issue with the blowing fuses continues. In my mind, there is either some short in the system, or some surplus load when the pump would start up. Once it gets going, it's fine. I have also kept it oiled a few drops a year.

I've already replaced the zone board, and the coupler. When I had the pump off, I checked the motor mounts and all looked fine. I'm wondering now if the issue is with the bearing assembly.

In another thread, IronMan suggested that I should have bought a Taco 007/008 or Grundfos ups15-58has for my application, but I already have a new bg 100 pump I bought off eBay on hand. Oh well...

I'm thinking that this weekend, I should try and replace the pump. I assume that I can leave and reuse the pump body plumbed, since I have ball valves above and below the pump. Another thought I had was simply replacing just the motor (since this way, I wouldn't have to break any plumbing seals), but I read somewhere that water due to a leaking bearing assembly could a surge in amp at pump start-up. When I was replacing the broken coupler a few weeks back, I had accidentally loosened one of the nuts holding the bearing bracket to the pump body and some water leaked out from behind the nut, which makes me further suspect that there is some kind of leak. -- THIS IS unless there is supposed to be water coming out of the pump body as it's plumbed inline...

To summarize, my questions are as follows:
1. do you think a bad bearing assembly could be what is blowing the fuse on my control board or could it be something simpler? I do have a multi meter and a clamp meter but would need to know what to do with them.
2. if I replace the bearing assembly, must I bleed the system thereafter despite having shut off valves above and below the pump in question?
3. is there supposed be water coming out of the nut holding together the bg 100 pump body and the actual pump/motor? (https://media.statesupply.com/filemanager/s/s/ssc-cat_bg-series-100.pdf)

Thank you all!

photo IMG_9546.jpg

photo IMG_1552.jpg

Comments

  • hot rod_7hot rod_7 Posts: 9,030Member
    Yes you would need to determine the current draw when that zone pump fires up. A clamp around meter would indicate the current draw. Clamp around the wire at the relay, or at the pump if there is more space to get around.

    A tights of failed bearing in the motor or pump assembly could be the cause of the high current draw.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • DZoroDZoro Posts: 482Member
    Time to update the pumps, before you loose another control board. Correct pumps probably will take care of the other issues as well.
  • hot rod_7hot rod_7 Posts: 9,030Member
    Circulators connected to a single header like that need to have check or flo checks on each circuit to prevent un-wanted flow or flow reversal.

    Personally one small P circulator and zone valves is a better option in my opinion.

    You have a lifetime supply of pumps if the system only used one and you have zone valves :)
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Solid_Fuel_ManSolid_Fuel_Man Posts: 1,196Member
    Yes, please just get rid of those huge energy hog 3 piece pumps!

    The electric savings alone would likely pay for all the stuff you'll end up updating, with the side benefit of reliability.

    I am also a one pump and valves guy. But that will require some piping etc. Cheap and dirty is just replace the pumps where they are, but you already know you will need to do some work to make that work.

    Best way is pumping away from expansion tank (pump on the supply) and valves can be either on the return or the supply. I like to put them on the return of each zone.
    Master electrician specialising in boiler and burner controls, multiple fuel systems, radiant system controls, building controls, and universal refrigeration tech.
  • GilmorrieGilmorrie Posts: 86Member
    The suggestions for modifying the system are relevant, but maybe not on Dec. 1. But, the question at hand is the fuse that keeps blowing.

    What fuse are you talking about? Is it shown in one of your pictures? What is the amp rating of the fuse? What is the rated amp draw and horsepower of the pump? What electrical loads go through the fuse besides the pump?
  • SuburbanHomeOwnerSuburbanHomeOwner Posts: 18Member
    edited December 1
    Thank you all for this great insight. The fuse that keeps blowing is a 6A slow-blow (littelfuse). I've circled it in the image below. You can see it next to the 3rd relay (?) from the right side of the board.

    It's not the board as it's new, and I recently switched the wiring from the empty slot just to the left, thinking that it was a faulty relay, or switch, or some part of the control board. (ie it used to be the 4th relay from the right blowing, so I switched it to the 3rd relay from the right, and it's still occurring. This is why I suspect the pump).

    below is a photo of some of the fuses i've gone through this heating season already...
    photo IMG_3895.jpg

    photo IMG_3243.jpg
  • GilmorrieGilmorrie Posts: 86Member
    The fuse should be sized based on the ampacity of the conductors supplying the pump. Replace the fuse with one of a higher rating.
  • Jamie HallJamie Hall Posts: 8,945Member
    An amp reading on the motor while it's trying to start would be helpful -- but not necessarily all that useful. Other's have mentioned a bad bearing either in the motor or the pump -- certainly quite possible. Could also be excessive misalignment between the motor and the pump; wouldn't take much. However, it could also be a failing capacitor. They do...
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • JUGHNEJUGHNE Posts: 4,942Member
    edited December 1
    That is a capacitor start motor. The cap assists the start winding to get the motor rotating. Once it is up to speed....maybe a second or so....a centrifugal (mechanical switch...you hear "click" close, ready for the next start up, when the motor shuts off) disconnects the start cap. If the cap is not up to par or the switch does not drop it out of the circuit then the current will stay high enough to blow the fuse. The cap can explode if left in the circuit too long (seldom, but I know it happens...don't ask).

    So if you have the time window change the cap.
    If not then change the entire motor if you have a replacement.
  • HVACNUTHVACNUT Posts: 1,589Member
    edited December 1
    > @Gilmorrie said:
    > The fuse should be sized based on the ampacity of the conductors supplying the pump. Replace the fuse with one of a higher rating.

    DO NOT INSTALL A LARGER FUSE.
    The circ relay contacts on the SR506 are rated to 1/3 HP, 6A max @ 120v.
    A larger fuse will melt your nice new board.

    An ammeter with min/max capture capability will steer you to a wet rotor pump.
  • Jamie HallJamie Hall Posts: 8,945Member
    HVACNUT said:

    > @Gilmorrie said:

    > The fuse should be sized based on the ampacity of the conductors supplying the pump. Replace the fuse with one of a higher rating.



    DO NOT INSTALL A LARGER FUSE.

    The circ relay contacts on the SR506 are rated to 1/3 HP, 6A max @ 120v.

    A larger fuse will melt your nice new board.



    An ammeter with min/max capture capability will steer you to a wet rotor pump.

    This is an excellent general point when dealing with circuit boards and relays -- the folks who build these things, though we often think they are perverse idiots, usually have some idea as to what current the various bits can take, and for how long. If they put in a 6 amp slo blo, there's a reason for it somewhere in there. Or a 1/2 amp fast blo. Or whatever. Always, always replace a fuse with the same amperage and speed rating.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • EBEBRATT-EdEBEBRATT-Ed Posts: 4,499Member
    First
    1. Don't install a larger fuse you will burn up your new board.
    2. Check the amp draw of the suspected pump and also check the amp draw of whatever runs through the 6 amp fuse. (If it feeds anything other than that one pump.)

    3. Buy a RIB Relay #RIBU1C

    4. Wire the coil of the relay, The coil leads on the relay will be white with a black stripe(HOT) wire it to where the pump hot wire is now wired and remove the pump hot wire for now.

    The other coil lead will be white with a yellow stripe. Wire that lead to wherever the pump white wire is terminated and also leave the pump white wire wired to where it now is wired.

    5. Then take the pump hot wire you removed above and wire it to the NO contact wire on the relay (the orange relay lead). Then take the yellow relay lead and connect it to 120 volt hot supply wire.

    if you do this the control board will pull in the rib relay when you need heat. The pump power wire will run through the relay contacts. The pump will operate the same as it always did.
  • SuburbanHomeOwnerSuburbanHomeOwner Posts: 18Member
    edited December 1
    Yes, I figured there was a reason for the manufacturer sizing the fuses as is. The old SR506 used an even smaller 5A slow-blo fuses so makes sense. These things are meant to blow to prevent a larger issue.

    To answer @JUGHNE, the motor mounts looked just fine when I had taken the unit apart to change the spring coupler.

    photo IMG_3078.jpg

    photo IMG_3077.jpg

    I know that a wet rotor like a Taco or a Grundfos would likely alleviate my issues, but unfortunately, I already spent money on a brand new BG100 pump (that was before I joined this forum, and was advised otherwise for good reason). Oh well. I have it on hand so feel obligated to use it.

    All i can do now is somehow use the clamp meter I have (which doesn't look to have a min/max capture, but then again, I'm not 100% sure how to use this guy: https://www.amazon.com/gp/product/B072BPVGY9/ref=oh_aui_search_detailpage?ie=UTF8&psc=1), and try to figure out what to do.

    I'm thinking 3 options:
    1. replace just the motor portion of the existing pump and try my luck. If it ends up being the motor mount, then this may solve my issue and avoid breaking into the sealed water component of my heating system.
    2. replace the entire pump (except portion of cast iron pump body plumbed into pipe (volute?), which can be reused), with the new pump I have. This would fix a potentially bad bearing assembly. (i'm assuming there's a leak internal to the bearing assembly and water is mixing with the oil). This option I fear most because I have to break the water seals and I’m afraid of starting a leak I can’t stop. I’m not even sure I have all the right gaskets to reconnect the new pump to the old body volute.
    3. maybe i'm just not oiling the thing enough, and I should just fill the oil reservoir for the bearing assembly all the way to the top. I didn't know to oil the thing for the first 3 years I lived here, and it was only the last 2 years that I started adding the occasional drops of oil. Perhaps it's just empty...


    Thank you all for being so patient with me.
  • SuburbanHomeOwnerSuburbanHomeOwner Posts: 18Member
    @hot rod_7 , OMG I love that, and would half seriously consider it!
  • hot rod_7hot rod_7 Posts: 9,030Member
    I thought I saw a ECM motor replacement for those pumps, recently? Maybe an aftermarket brand. It would probably be more $$ than an ECM pump replacement, however.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • NY_RobNY_Rob Posts: 1,221Member
    edited December 1
    A new 007 is under $100 at your local Home Depot.

    Buy it, install it, purge, done!

    Problem solved in 30min for $100.

    Resell the B&G "as is" on ebay if you feel the need to recoup a couple of $$.
  • JUGHNEJUGHNE Posts: 4,942Member
    I was not talking about motor mounts.....though if really bad can be a problem for the coupler.
    I was referring to you having an electrical problem within your motor.
    It could be a bad start capacitor and/or start switch within the motor......with the intermittent problem you have these could be the issue.
    If you changed the cap or entire motor.....all on the dry side of the pump....it might solve your problem.

    Have you oiled all 3 points....2 motor cups a little.....1 pump point, just pull the square cover with the oil cup off and you see felt inside that should be wet with oil.

    These pumps were great in their day, but as you gather from others here that day is becoming limited.
    For me once the shaft seal leaks water they go to the bone pile.
    I have about 4 buckets full of misc parts for all other repairs of the old 100's.
  • Solid_Fuel_ManSolid_Fuel_Man Posts: 1,196Member
    edited December 1
    The 6 amp slo-blo fuse is in place really yo protect the little relay in the SR5xx switching relay. At 6 Amos, the engineers figure 99% of all applications will be covered and all is well. The fuse blowing at long intervals I dictated one of two things:

    1. Your old 3 piece has a marginal bearing in either the pump or more assembly which is adding friction at some times and causing higher that the slo-blo fuse's ratungs.

    2. The in rush current of that split phase motor is such that with each start it hits the fuse enough to deteriorate it enough that after a given number of starts it blows.

    You have other pumps of the same capacity on this SR5xx switching relay so I'm inclined to believe its reason #1, which means just replace stuff.

    I too would just sell the 3 piece on Ebay, and replace with a readily available wet rotor pump of your color choice. I have had excellent luck with the green ones. A 007 is cheap and available at most big-box stores so you dont even need to wait for the internet to deliver one to you. I've had hundreds of the wet rotor last 20+ years with no maintenance, this is due to the fact that the system water is the lubricant for the pump, no external oil is needed, and no coupling, and only 2 bearings, both are water lubricated. Your 3 piece has 2 bearings in the motor, and one in the pump housing, with that mechanical seal to keep water in the pump and out of the basement.
    Master electrician specialising in boiler and burner controls, multiple fuel systems, radiant system controls, building controls, and universal refrigeration tech.
  • Solid_Fuel_ManSolid_Fuel_Man Posts: 1,196Member
    This is the rotor of a wet rotor circulator I cut open a few years back. This was a bronze 0010 used as a DHW recirc pump running 24/7 and the impeller disintegrated due to very poor piping practice causing cavitation. The motor still turned this, but no water moved.
    Master electrician specialising in boiler and burner controls, multiple fuel systems, radiant system controls, building controls, and universal refrigeration tech.
  • SuburbanHomeOwnerSuburbanHomeOwner Posts: 18Member
    Thanks everyone again. The fuse blew again last night, so since I have this extra bg100 on hand anyway at it was late at night and 20 degrees out, I replaced the dry-side just to see what would happen. I also followed directions on another thread to bleed the system, so am hoping it was some motor issue and not something drawing amperage on the bearing assembly.

    Rest assured, I will switch to a wet rotor pump at first chance once any of these remaining guys are up for replacement. Thanks all again. Fingers crossed!
  • GBartGBart Posts: 646Member

    This is the rotor of a wet rotor circulator I cut open a few years back. This was a bronze 0010 used as a DHW recirc pump running 24/7 and the impeller disintegrated due to very poor piping practice causing cavitation. The motor still turned this, but no water moved.

    looks more like super heated steam
  • GBartGBart Posts: 646Member
    the B&G is a waste for most residential, it was the go to 50 years go, way over sized but its what we had, variable speed cartridge is the way to go now
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