B&G Series 100 randomly shuts off?

1075NH

Hello, been a regular browser here for some time, great site. And now finally i would love the help of some people if they could.
I bought my home almost 4 years from a union pipe fitter so needless to say this homes heating system is extremely complex and very overbuilt. I have radiant floor heat, baseboard radiators, an oil boiler (Viessmann), an outdoor wood boiler (Greenwood Aspen, heavily modified), Aos roof mounted hydronic panels, 3 hot water tanks and all sorts of commercial grade expansion tanks, pumps, heat exchangers, etc. I don't even understand. I had a residential heating guy come out here to look at my system so i could have a better understanding of it and he gave up and told me to call a commercial level tech.

Than being said, my current issue is on my outdoor wood boiler. Mounted at the boiler is a B&G series 100 bronze circulator pump that pumps the water from the boiler to the heat exchanger in my garage and then back to the boiler. I have used my wood boiler every winter with zero issues until last year. Within a few days of starting up the boiler for the year last winter the water was not getting very hot at the heat exchanger despite the temp at the boiler being 180. This was never an issue in the past. Then the boiler started boiling over and dumping water out the top (open system) very often. I noticed the circulator pump was turning on and off randomly. Which certainly explains why i was having the issues. The boiler was overheating because when the pump would stop the boiler had no way to get rid of the excess heat. Then the pump would kick on the boiler would cool down enough and id have heat and things would be fine. Then it would happen again. This was happening multiple times a day. I finally shut the system down until now when i finally have time to hopefully fix it.

My outdoor boiler has one power circuit. When the breaker is switched on the circulator pump runs continuously and the electronic boiler temp control is on. The only thing the temp control does is turn the fan for the firebox on and off. Their is no Aquastat on the pump. Its directly wired to AC. The pump always ran 24/7. I removed the pump yesterday and used a Supco motor tester and it instantly failed the test. The pump looks to be at least 25+years old. So i'm not surprised. But when i wired the pump on my workbench it kicks on and seems to run fine (granted, not under any load) and its quiet. I could pretty easily spin the pump shaft on the bearing housing on the boiler. So i know that's not seized.

So all of the above being said, the simple question is.... Would a B&G pump randomly turn on and off despite having power constantly applied? Even when the pump was not running the boiler control was still on. So i know their was power there. Is their some sort of thermal overload inside the pump motor? Could the pump perhaps be seizing up and then un-seizing itself despite not doing enough damage to itself to allow it to still work on my bench test?

Any help from you experts would be appreciated. I searched every source i could find about these pumps and have not seen anyone talking about this issue. Thanks!

STEVEusaPA

Maybe the impeller is sticking, your motor is running to overload and shutting off. Then it cools and kicks back on.
First I would make sure my power was clean, checking volts and Hz, making sure all connections were good and tight.
Then, I'd connect the pump back up to the impeller, turn it on, and read the amp draw, starting and running, and see if the running amps start to drift higher. If it does it there and the readings are significantly higher than on the bench, I'd suspect the impeller. You can get parts and rebuild them, but it's easier to just replace the whole thing to a modern bronze circulator.
Add isolation flanges for the next change out.

As far as your controls, I'd add some kind of high limit that shuts down the boiler, or at least notifies you, to prevent a runaway boiler.
@Ironman is an expert on wood boilers (along with everything else), and could probably advise you better on how an outdoor boiler should be piped and wired, and which controls are best.

1075NH

Thanks for the response Steve. I will run all those tests you suggested and see what i come up with. I found a lightly used replacement motor and bought a brand new coupling. Both should be here next week. I'm going to reassemble it with the new(er) motor and see what happens. But definitely going to check the amp draw with it too.

I had contemplated replacing the whole pump assembly with a cartridge style setup. Does Taco (or anyone) make a direct bolt in replacement that can replace the whole B&G setup without having to make changes to the piping? The whole back of the boiler is done in copper with ProPress. Really not looking forward to having to make any major changes to the piping if it can be avoided.
As for the boiler control, the current system shuts off the blower at 180 degrees which with a working circulator pump is my safety system. But with the pump failure even with the blower off their is much residual heat it just goes out of control. I'd love to hear about ideas for a fail-safe system.

Mike_Sheppard

EDIT: ignore my capacitor advice. I was thinking of the series 60 pump not the series 100. Series 100 doesn’t have a capacitor. My bad!!

If you have a multimeter that can read capacitance, check the capacitor. If the capacitor has gone bad the motor will go off on thermal overload. If I remember correctly those normally have 10uF capacitors in them. Don’t forget to discharge the capacitor first before touching the terminals.

The amp draw will change depending on how much water you’re moving, but it should not exceed the rated amp draw indicated on the motor. If your pumps turns freely and the amp draw is less than nameplate, and motor is overheating, your motor is bad. If the amp draw is higher than namellate then the impeller could be rubbing, bearings could be going bad, capacitor could be bad, or motor going bad.

If everything spins freely it is most likely motor or capacitor.

Big Ed_4

Yes it could it has a thermal over load , change the motor

1075NH

I did't think B&G Series 100 pumps had capacitors? Their isn't one i have seen listed in any parts diagram and under the wiring access cover is simple a set of leads. Not the typical capacitor style motor hookup.

Solid_Fuel_Man

As far as safeties on an open boiler, that's it. Turn off the fan at 180 and run the pump 24/7. Boiling over is what happens, a closed system is a bit more complex with gravity flow dump loops etc.

All the above is good advice, although I'm not a fan of 3 piece circulators in today's world. That running 24/7 is costing you some coin in electricity. Even a change to a wet rotor will give you some electrical savings. Do you treat the open system with any chemicals? Shouldn't need a bronze circulator there, I bet it was put in because he got it from a job (i have lots of that too!)

Mike_Sheppard

> @1075NH said:
> I did't think B&G Series 100 pumps had capacitors? Their isn't one i have seen listed in any parts diagram and under the wiring access cover is simple a set of leads. Not the typical capacitor style motor hookup.

You are correct. My mistake. I was thinking of the series 60 pump. Thank you!

HVACNUT

> @1075NH said:
>
> Than being said, my current issue is on my outdoor wood boiler. Mounted at the boiler is a B&G series 100 bronze circulator pump that pumps the water from the boiler to the heat exchanger in my garage and then back to the boiler. I have used my wood boiler every winter with zero issues until last year. Within a few days of starting up the boiler for the year last winter the water was not getting very hot at the heat exchanger despite the temp at the boiler being 180. This was never an issue in the past. Then the boiler started boiling over and dumping water out the top (open system) very often.


For starters, IMO, since you frequent this site, you should've come here first.
Maybe talk you out of a
"lightly used replacement motor", and politely sway you to getting a wet rotor circ.


Open system or not, where exactly was the water coming from? Boiler relief valve, domestic relief valve?
Why was it boiling over? Faulty or bypassed limit?
You wrote 180 so we're assuming that's the limit setting on the boiler side?


I noticed the circulator pump was turning on and off randomly. Which certainly explains why i was having the issues. The boiler was overheating because when the pump would stop the boiler had no way to get rid of the excess heat.


Like the others guys said, the motor probably opened on thermal overload. Admittedly I dont know if they're protected. I can't remember because I haven't seen one in forever. Ah but I do know, a couple drops of oil...
However, anytime the boiler makes limit, the burner circuit should open, regardless of whether or not the circ is running, and it should in no way build enough pressure to start blowing water all over the joint.




Then the pump would kick on the boiler would cool down enough and id have heat and things would be fine. Then it would happen again. This was happening multiple times a day. I finally shut the system down until now when i finally have time to hopefully fix it.
>
> My outdoor boiler has one power circuit. When the breaker is switched on the circulator pump runs continuously and the electronic boiler temp control is on.

Why is the circulator on a switch and not being controlled by a thermostat. And the fan circuit should be wired through a "close on rise" aquastat, sequencer or other time delay relay.


So it seems theres at least two issues going on, one being you need a new circ. Use the 100 as a doorstop and get a properly sized wet rotor pump.
And two being theres something wrong in the burner circuit and that needs to be addressed. Not just a new circulator.

If you can post some pics of the piping, boiler, controls, wiring diagrams, that will help.

kevink1955

HVACNUT Are you aware this is a wood burner, there is no burner curcit to cut out on high temp. It appears that the fan is a combustion air blower and should be shut down on high temp to reduce the fire rate.

It is an open system so it was boiling due to the circulator stopping and the system loosing it's ability to remove the wood fire heat, no relief valve that i know of on this type of system.

I agree with almost everyone else, ditch the Model 100 and go with a wet rotor, the electrical cost alone makes it worthwhile

HVACNUT

> @kevink1955 said:
> HVACNUT Are you aware this is a wood burner, there is no burner curcit to cut out on high temp. It appears that the fan is a combustion air blower and should be shut down on high temp to reduce the fire rate.
>
> It is an open system so it was boiling due to the circulator stopping and the system loosing it's ability to remove the wood fire heat, no relief valve that i know of on this type of system.
>

Apologies. I'm not at all familiar with a HX through a wood burner and I'm thinking of the heat/domestic open system.
Regardless, shouldn't there be some kind of fail safe in that situation? Bypass damper?
Bucket of water with rope and pulley? 🤪

> I agree with almost everyone else, ditch the Model 100 and go with a wet rotor, the electrical cost alone makes it worthwhile

kevink1955

HvacNut,

I like the bucket of water, rope and pulley idea. Most of those boilers use the combustion blower as the firing control. No air means low fire but they can runaway without water flow. Sounds like the OP has a good grip on how the system works, he just needs a reliable pump

EBEBRATT-Ed

@1075nh,

You could put a flow switch in the piping and wire it to shut your fan down on loss of flow.

Or you could use a current sensor to shut off the fan if the pump is not drawing any power.

Flow switch is probably better., a current sensor may not pick up a broken coupling with a running motor

Solid_Fuel_Man

Once it reaches 180 the fan turns off anyway. Flow switch isn't going to prevent much, just give you a few extra minutes before boil over.

1075NH

Thank you all yet again for the insight so far. As Kevin pointed out, yes, this a wood boiler. So the only "burner control" is the blower turning on and off. And even when it shuts off the fire can continue to burn for quite a while. It's not an issue so long as that pump stays running. Because the heat exchanger can handle it and i even have two huge forced hot air radiators in the garage that will turn on automatically if the water temp gets too high. But this pump is critical that it remains running. If it doesn't then the boiler runs away and other than losing my expensive antifreeze as it boils over and out the top and makes a mess, their isn't any damage thankfully since it usually cools down long before it boils off so much that the metal warps.

Since i already ordered a new motor i figure its worth a shot replacing it and see if that's what the problem is. If the problem persists than maybe as others have pointed out the bearings are seizing and if that happens i am going to cut my losses and go with the Taco replacement. If i understand correctly what i have been reading online, the Taco 007-HBF5-J will be a direct replacement for the B&G Series 100? Just bolt in the new pump at the flanges? no piping to modify?

Ill take some pictures this week.

HVACNUT

IFC circs in parallel with flow switches and auto change over. And an alarm or light.
Screw that boiler over stuff.

ratio

Replace the motor mounts when you you replace the motor. When they get soft they take it out the pump coupling.

1075NH

1075NH

So this is the piping arrangement on the back of the boiler. You can see the pumps location (motor removed). Their aren't any leaks, the discoloration and staining is from condensation since everything you see is normally covered in insulation that i removed while i'm making repairs.

1075NH

New motor and coupler arrived so i installed it today and its running right now. Not lighting the boiler but want the pump to run for awhile and see if their are any issues. Here is the old pump with the "new-er" replacement.

1075NH

Old pump readings at startup and then running. Plus the insulation test

1075NH

The replacement motor showed practically identical startup and running readings. But a much better insulation check. Voltage at the boiler was stable as well.

Solid_Fuel_Man

You have some nice test equipment!