24v relay with loud humm and no noise from circulartor

[plumbud]

Hello, I have a weil Mclain series 10 CGM boiler, 27 years old apparently. Still runs really well. It heats three zones, I have a one story home, pressure is a constant reliable 15 psi and the boiler heats well, one day I noticed the boiler relay humming extra loudly and wouldn't turn off. I isolated the loud buzzing one one specific zone, if i disabled this zone the other two zones performed perfectly boiler turns on, sends heat turns off when finished, the one zone in question, the relay buzzes, the boiler heats, but the zone does not get hot, relay buzzes and stays on as the thermostat is calling for heat, when i feel the pipes the section for this zone around the boiler gets quite hot, but the return pipe stays fairly cool, the circulator gets extremely hot, but just beyond the circulator doesn't get very hot past say, 4 feet. i'm not getting any noise from the circulator the other two circulators you can hear them humming, i'm not sure whether my circulator is the issue or if my relay is going bad. I've just purged the system 15 minutes a piece, and double checked to make sure i didn't see any air. Any advice is really appreciated, thanks so much for reading.

 

[NY_Rob]

Check the zone valve on that problem zone, could be stuck closed, not opening all the way or just not operating.
Most zone valves have a manual operation lever or dial... give it a push/turn when the humming starts.

 

[Sponsor]

 

[plumbud]

I've actually looked over my system a few times i do not believe I have electronically controlled zone valves, but just regular shut off valves, it's an older system. thanks for the suggestion!

 

[plumbud]

My theory of repair would be to 1. replace the 24v relay, if that doesn't resolve the issue, then replace the circulator pump, does this sound right?

 

[NY_Rob]

How many thermostats do you have?

 

[plumbud]

three thermostats, one for each zone.

 

[Dana]

Is this one of three zone relays operating different circulator pumps, or it it internal to the boiler, operating a primary pump or ...???

 

[plumbud]

I'm pretty sure that the zone relay operates different circulator pumps, and i'm thinking the culprit is the zone relay itself, but the zone relay is only failing on one zone, this is the replacement part I've been thinking of swapping out. I notice that it buzzes louder when trying to operate the zone that's currently not working, but when it operates the zones that are working, it's a lower normal hum.. so maybe it's starting to fail? this is the piece that humms hope this helps, if not I can take photos.

http://www.supplyhouse.com/Weil-McLain-510-350-223-Plug-In-Relay-w-24V-Holding-Coil

 

[NY_Rob]

We have established you have three zones....

Does each zone have it's own circulator pump, or does each zone have it's own zone valve?

 

[Dana]

A zone relay only operates a single pump at a time, not multiple pumps independently.

Does your system have a pump each zone, and a fourth pump directly pumping the boiler, (typically a Taco 007 mounted in the side, as shown on p.23 of the manual.)

Or are the zones operated with zone valves, all being pumped by the single pump, energized by the noisy relay?

If there is a stuck-closed zone valve the circulator pump and relay might make noise to the higher current loads in the windings of effectively zero flow, and if it's quiet when other zones are operating the relay and circulator pump are fine, but the zone valve may need to be replaced.

 

[plumbud]

Each zone has it's own taco circulator 007. it's strange because I only seen 3 taco pumps on each zone return I've never found the 4th pump.. I don't believe there is one because it should be outside the boiler correct? I'll have to grab some photos. I don't see any zone valves the only electronic controls run directly to the taco circulators.

 

[NY_Rob]

With the information we now have and info from your original post:
"the one zone in question, the relay buzzes, the boiler heats, but the zone does not get hot, relay buzzes and stays on as the thermostat is calling for heat, when i feel the pipes the section for this zone around the boiler gets quite hot, but the return pipe stays fairly cool, the circulator gets extremely hot, but just beyond the circulator doesn't get very hot past say, 4 feet."

You could have a locked/binding rotor circulator on the trouble zone.
Activate one of the working zones, place your hand on the active circulator- note the sound and feel the vibration it makes.
Now activate the trouble zone, place your hand on it's circulator... do you hear it running, do you fee it vibrating?

 

[plumbud]

locked/ binding circulator sounds plausible, last time I touched the circulator for the trouble zone, I didn't feel or hear any sounds of movement, however that circulator gets extremely hot, hotter then other working zones.. I'll double check it, in the event that is bound, I believe you can just drain the system and then unbolt the circulator itself to inspect the fins and see if there's any debris around the circulator correct?

 

[NY_Rob]

If you can't hear it, and there is no vibration coming from it- the next step would be to check it's current draw with an ammeter.
Most homeowners don't have an ammeter, so you'll have to pull the pump and check for a bound rotor. In most cases you won't find debris in the impeller housing, binding is usually due to bad bearings, rust, etc. If it's bound... don't try to free it up, replace it.

On the newer 007's you can just pull the motor "cartridge" itself - you don't need to remove the whole assembly.

http://www.supplyhouse.com/Taco-007...nt-Cartridge-TAC007-042RP-for-007CI-4116000-p


https://www.youtube.com/watch?time_continue=30&v=3Gb96MSuwnA

 

[plumbud]

Thanks for the excellent advice! I'll double check and see if I feel anything or hear anything coming out of that circulator.

 

[Dana]

What NY_Rob said- check it with an ammeter, and compare it to the other pumps. It could be a locked rotor (plausible), or shorted windings (even more likely) that's keeping it from spinning, and causing it to pull lots of power.

The replacement cartridges are sometimes more expensive than replacing the pump. If replacing the pump, an ECM drive version will cut the total power consumption by a large fraction, and even though it's a more expensive pump, will usually pay for itself over time.

 

[plumbud]

After inspecting the circulator last night The only noise you hear is a very unique electrical buzz completely different from the low humm of circulating water, as was said probably because the relay is outputting more power then needed to get the rotor moving so judging by this i'm confident it's a seized rotor.I'll replace the entire circulator since it's so old. Thanks again for your terrific advice!

 

[NY_Rob]

Excellent, please post back with results once the replacement pump is in place.

 

[Dana]

Even though it's an up-charge from a Taco 007, something like a VR1816 or a lower power Grunfos Alpha would allow you to dial in the flow, and would use less than half the power. You can find them for under $200.

The ECM drive Taco 007E-F2 is a single speed version, a more efficient drop-in replacement for the older 007s for about $120 (at internet pricing.)

 

[plumbud]

I did want to ask about that, Furnace being around 27 years old, I actually had to replace alot of parts before i got to this point.

1. Initially the pilot wouldn't light because the connection was weak, replacing the pilot starter resolved the problem.
2. Ancient Auto air vent started weeping from my air scoop( float stuck) Replaced that solved problem.
3. When i went to refill the system, my Watts S1156f auto fill valve snapped apart in my hand like a nestle crunch, replaced that solved the problem
4. Heating and PSi gauge frozen, filled with rust, replaced that solved problem.
5. refilled and purged the system everything ran perfect for about a week until the Taco pump failed.
I also note that the purge valves are all dried up and slow leak for hours after a system purge and i want to replace those, probably in the spring, as well as the emergency pressure release valve leaks.



My story shows my system is down to it's bones The copper piping is still in good condition and the furnace itself seems to be performing in good condition, House heats nicely. My system is Natural Gas, two professional heating technicians have said the furnace itself looks fine.

But the question comes up regarding whether to purchase a new system or not. I absolutely don't mind doing the work. Great learning experience. Is refurbishing actually worth it in the long run?

Will a heating company charge me for new circulators either way?
Will purchasing better circulators on an older system lower my electricity and heating bills?
is a 27 year old furnace just wasting amounts of fuel?

Thanks again for your support and knowledge. I really appreciate it.