Is the pump dying?

tamosius

Please see the video, I captured the noise that the main circulation pump is making when there is a call for radiant heating:
https://youtu.be/TYRWx4ZaJx0

Besides that it's quite noisy, on 10 second mark the pump will make "oynk" noise, kinda trying to stall?

I don't think it's entrapped air, since water is coming right away when unscrewing that center vent plug, so I don't think it's running dry.

The system is pressurized to 17 psi.

The pump kinda stops making noise when there is a DHW call, and it reaches higher temperatures.

I do have hydronic separator installed, throwing out there, just in case.
Do those pumps have ball bearings? When I switch to higher speed (running at speed 1 gives me best delta T, though), it does sound like ball bearings are warned off.

I haven't removed and took it apart yet, kinda next thing to do.

The system I suspect is quite dirty, since it doesn't have dirt separator, and pipes are black from inside.

EBEBRATT-Ed

The pump is lubricated by water. Dirt, grit and sludge can cause it to fail. How old is the system? You may want to flush, have water checked etc.

Big Ed_4

To add from Ed's post , loosen the center screw to purge any air ...

pedmec

with the pump "NOT RUNNING"

tamosius

I have the pump purged before, didn't mention, it seemed too obvious.

The system is around 12 years old. I think I have replaced water in the system once. I 'm looking for a decently priced dirt separator now (alibaba has decently priced, they look exactly as one of the branded ones... it might be the same stuff, but like x10 cheaper). Sorry, tangent...

Back to a regular programming. Show and tell time, after I have removed the core of the pump, I found some sort of fibers on the impeller, no idea waht they are from:



All debris I could remove next to a penny for comparison. Those on the right, brownish, they fell off from the *inside* of the core. Black ones were stuck in the impeller:



Put it back together, and while the pump makes horrible noises on speed 2 and 3, on speed 1 it's whisper quiet.

I think what is happening with that pump is that it has a permanent magnet core (am I right?), and all the magnetite is stuck around it, since the water is used as lubricator.

Does anyone know who sells cores for Wilo pumps? I found a bunch on aliexpress, but they can't spec **** - it would be like buying a cat in a bag.

tamosius

Oh, another question. The way the core of the pump is put together, it is not possible to take apart and clean? That flat grove is there in case one would like to spin the impeller in case it's stuck, correct?

hot_rod

That is a PSC type pump motor so it does not have permanent magnet. ECM type circ do.

Yes you can pull the rotor from the rotor can and clean it out. It has a bushing, not ball bearings

tamosius

hot_rod said:

That is a PSC type pump motor so it does not have permanent magnet. ECM type circ do.

Yes you can pull the rotor from the rotor can and clean it out. It has a bushing, not ball bearings

I tried to grab onto the impeller and pull it, but I couldn't. It's kinda loose, I can pull/push like 1/8" or 3mm, but then it would stop when pulling. I'll make another video to describe. I'm pretty sure some more curious minds could use that as a how-to manual.

I'll google more about PSC type motors, thanks, that's really helpful.

The best way to recycle is to fix the old stuff, right?

hot_rod

3 steps, remove motor.
Pull out rotor can, the big stainless part.
With a pocket knife separate the rotor from the rotor can.
Now you see the shaft and bushing in the can.

Grundfos uses ceramic shafts on the small UP series, it helps eliminate magnetite sticking, on ECM type motors.

If the shaft is scored or diameter reduced, your done

* probably not a factory approved hack.

tamosius

hot_rod said:

With a pocket knife separate the rotor from the rotor can.

* probably not a factory approved hack.

Fantastic! I appreciate for the pictures! Quite scary, not sure whether I should do that before the weekend, in case I would need urgently get a new pump.

I wrote to Wilo what I think about not selling rotary assemblies, once they responded that they don't sell rotary assemblies for Star line of pumps.
This is the biggest BS, considering that replacing a rotary assembly is faster than replacing whole pump, since I don't need to redo wires. From that point of view, it's even safer (that really doesn't concern me that much, since I'm fine doing electrical work, though the argument still can be made).

From logistics point of view, less weight needs to be sent all over the place, less shelve space is needed to store them, one rotary assembly normally covers 3-5 variations of pumps, so that is no brainer either. From manufacturing point of view, rotaries are assembled on a different line, and later are added as a unit into the casing, so that is not an issue either..
From waste reducing point of view, what's the point replacing the pump casing with flange if they have no issues at all, and normally would last over 20 years. Mine is 12 years old, and has no signs of anything going bad with those parts of the pump.

So really, it's not a brainer. Just sell rotary assemblies at 1/3 price of the pump, and I would happily replace those assemblies more often just to keep the noise down.

/The end of the rant

Now, are there any brand, who really going that direction, ie, "we do good pumps, and we expect that you will only need to replace moving parts, so we sell them" ?

If I end up replacing a pump at some point, I will go with such brand just because I can't support this wastefulness that Wilo is pushing on us.

hot_rod

I think the PSC motor Star series exists just for the US market. Most everywhere else has gone all ECM technology.

I keep hearing the DOE is going to phase out fractional HP PSC type pump motors and require all ECM. But that date keeps getting pushed out. I've heard by 2025 lately.

If you have more than one zone an ECM in delta P mode will save operating cost and allow your system to have cruise control. The pump with automatically adjust itself to changing flow requirements.

Probably find that Star or equivalent brand on e-bay for cheap Generally expired date code stuff.

tamosius

hot_rod said:

I think the PSC motor Star series exists just for the US market. Most everywhere else has gone all ECM technology.

I keep hearing the DOE is going to phase out fractional HP PSC type pump motors and require all ECM. But that date keeps getting pushed out. I've heard by 2025 lately.

If you have more than one zone an ECM in delta P mode will save operating cost and allow your system to have cruise control. The pump with automatically adjust itself to changing flow requirements.

Probably find that Star or equivalent brand on e-bay for cheap Generally expired date code stuff.

Very interesting info. I definitely would like a replacement that is future proof.
Though, my system still doesn't have a magnetic filter, so any little magnetite would be oh so attracted to a permanent magnet of an ECM pump (as far I understand, it does have a permanent magnet).
It is my plan, though, to address that by cleaning, purging, and installing magnetic filter at some point during coming summer. But that is kinda longish term.

So, when it comes to finding a proper replacement, my boiler is Viessmann Vitodens WB1B-26.
It does have low loss header (LLH) installed, separating DHW loop and radiant heating loops from boiler's loop, which is using mentioned Wilo S21 pump.

Both DHW loop and radiant heating loops are run by separate pumps (both are using Wilo Star S16), instead of having a divertor valve that would switch based on whether it's radiant heat vs DHW call. not sure why, maybe the intention was to run those pumps at different speeds?

So, to sum it up, I have 3 major loops with 3 pumps, and boiler is separated from heating loopers using LLH, but I'm repeating myself now.

Now, radiant heating has 3 manifolds, and in total, 14 loops, and each loop would have a valve.
All these 14 loops are different sizes.
Each bedroom (3) + bathroom = 4 loops have own thermostat. They all have kinda drastic differences in requirements how warm/cool we want to keep them (just explaining the reasoning behind so many zones)

The main living area is yet another zone, 6 loops. All those loops are installed under the plywood subfloor, using aluminum heat spreading plates.

Basement has another 4 loops, all under the same zone/thermostat, pipes are encased in the concrete floor (so, lots of thermal mass).

So, having so many loops, with different requirements when and how much we want to heat, probably explains LLH.

We have Taco controller for DHW priority, and it sends a signal for DHW vs radiant heat requests to the boiler, and the boiler, once it gets a request to start working, starts the pump (ie boiler's pump ON/OFF is controlled by the boiler).

TLDR: this is my system pretty much, except that for C there are 3 manifolds and thus BTU required for C is variable:



What pisses me off with all this installation, is that back then, Vitodens couldn't modulate to really low levels, and the minimum output is 34 MBH / 9.9kW which is insane high, if only a bathroom, or some bedroom is calling for the request to heat, and the boiler is short cycling during the day.

So, anyway, considering that I need as few BTUs as possible, I run my Wilo S21 at speed 1, and so even when we are heating a water tank, it actually produces enough heat to reheat water while running at lowest levels..

Conclusion: due to current system design, I don't see a need to have a variable pump for the main loop (ie at the boiler), because the pump load is never changing because of LLH.
Maybe, I could run that pump based on delta T, but that isn't going to help too much, since the boiler is oversized anyway in most cases?

OK, finally we are getting to a juicy part. Viessman suggests Grundfos 15-58, or Taco 00R.
When I looked at Taco 00R, I noticed that the curve it has is like running the Wilo S21 or Grundfos 15-58 at speed 3.
Based on Viessmann manuals, te best efficiency are at lower flows, and those are achieved running those pumps at lower speeds, so I see a bit of contradiction there. The only explanation I can come up is that they assume that loops are going to be pushed by the same pump without LLH, on the other hand they strongly recommend LLH anyways.

While looking at Taco pump replacement guide (https://www.tacocomfort.com/documents/FileLibrary/Taco Circulator Replacement Guide.pdf) it seems that Grundfos 15-58 and Wilo S21 replacement is Taco 0015.
But, when I enter flow and head loss parameters in pump suggestion calculator based on pressure drop from Viessman manual (4.2GPM / 7ft), Taco 0015 is nowhere to be seen, and suggested pump is Taco 0013, 0012, I guess smaller ones.




I must be doing something wrong, or I don't understand one should use a system's pressure drop based on flow rate to pick a pump based on its characteristics - I thought those two graphs would need to overlay, and crossing point shows a theoretical flow rate.

Sorry for the long post, there is lots to unpack there. Please do feel free to pick anything being said apart. I'm pretty sure I can learn.

hot_rod

A 15-58 Grundfos would be my choice . A 3 speed pump for adjustability

tamosius

hot_rod said:

A 15-58 Grundfos would be my choice . A 3 speed pump for adjustability

why would you need adjustability for a main/boiler side pump where there is LLH?

PC7060

hot_rod said:

A 15-58 Grundfos would be my choice . A 3 speed pump for adjustability

I recently looked at the data sheet for the new model Alpha (15-58FR). I’m curious about these bullets; are bearing better that previous Alpha 2. I assume the auto-deblocking  is  a correction for the stalled pumped issue after long stop period. 

• Anti-magnetic shafts and bearings
• Robust Start function enabling automatic deblocking

hot_rod

tamosius said:

A 15-58 Grundfos would be my choice . A 3 speed pump for adjustability

why would you need adjustability for a main/boiler side pump where there is LLH?

So you can adjust flow to obtain the delta t across the boiler that you want or need 

hot_rod

PC7060 said:

hot_rod said:

A 15-58 Grundfos would be my choice . A 3 speed pump for adjustability

I recently looked at the data sheet for the new model Alpha (15-58FR). I’m curious about these bullets; are bearing better that previous Alpha 2. I assume the auto-deblocking  is  a correction for the stalled pumped issue after long stop period. 

• Anti-magnetic shafts and bearings
• Robust Start function enabling automatic deblocking

As far as I know the Alpha line has always had ceramic shaft and bearings.
ECMs are DC motors so starting torque is better than a PSC type circ.

Probably the best feature is the exercise function to run the motor occasionally during the off season

Generally it is crappy water that can seize the motor over long off periods. Hydronic conditioners can help with bad fill water