Grundfos UPS 26-99 FC?

MarkPFalade

What would cause the seal on a less than 1 year old pump like this fail? It is being used for both chilled and warm water (50% glycol). It has stopped moving solution even though it is turning and if you pull the end cap it leaks glycol. System temps go from 36*F to 120*F, system pressure from 11 psi to 20 psi. Haven't I heard about some Grundfos issues around here before? Any info wil be helpful

Thanks! 

EricAune

Not cavitating is it?

I had a similar problem with a Taco about a year ago, turned out it must have been a manufacture defect.   Changes out and have not had a problem since.



Have seen this on cavitated pumps though.

MarkPFalade

Thanks

I don't believe it would be cavitating. 20 feet round trip of 1 1/4" copper to a tank with the suction feeding off the lowest fitting. It's been running on low and was working like a champ,,, till the call came in. It was idle for a while between shutdown after summer and the startup I did for heat Thursday. Maybe a month or so. I don't know that it would be an issue. I'm just fishing for answers here. The crazy stuff always happens on the weekend. I plan to call them monday but thought I'd see what everybody around here had to say. I swear I recall some discussion of Grundfos problems somewhere.

Mark Eatherton

Not a blown seal....

When you pull the rotor plug, yo have direct access to the armature and it is normal to get fluid from there. In fact, as part of their commissioning, you are supposed to bleed air out of there to insure fully wetted bearing assemblies.



You might try unjamming the armature with a small flat tipped screw driver. If that works, you might have gotten some byproducts of glycol corrosion (you know those bluish green crystaline thingies you see on leaky joints) in the bearings, and locked things up.



ME

MarkPFalade

Hmph,

First day with the new Grundfos I guess. The armature IS turning, I found the fkuid when I was checking to see if it was. Did not know about the whole bleed thing. Why won't it pump??

Mark Eatherton

If the shaft is a turning...

WHILE the pump is powered, you either have a pump that is not fully purged, or a check or isolation valve that is not letting fluid through, or an impeller that has snapped off the shaft that is spinning.



If the shaft is spinning free with the pump in the off position, but doesn't spin when powered, you have a dead pump/ Could be the capacitor...



ME

rich pickering

1 year old?

Check the impeller. 

Jean-David Beyer

1 year old!

I do not know about the capacitors in induction motors, but if you remember the bad old days when cars used distributors and induction coils to generate the spark for ignition, I had a tune-up and after that, the car would barely run. The mechanic could not, at first, figure out what was wrong. He suspected the capacitor across the points of the distributor, so he replaced it with another new one (he had put a new one in as part of the tune-up. It ran worse than ever. On the theory that there could have been two bad capacitors, he tried a third. To make a long story short, it turned out that the entire lot of capacitors was bad, fresh from the factory.

MarkPFalade

yes

Pump spins while powered and has been pumping since February with no problems. There are no checks and all isolation valves are open. There is a wye strainer but I did a real clean job so I can't see it being clogged. That leaves impeller snapped off the shaft. Next question would be why? In other words, once I go through fixing it I don't want it to happen again. This is only the second grundfos I have ever purchased, I'm not exactly impressed.

Afterthought, if air makes it's way into the system can it pocket in this pump (mounted horizontally) and require that it be purged again?

hot_rod

a ball O solder

will jam and snap an impeller, stone, rust, any particle large enough to get between the impeller and volute. Do you have a strainer or dirt separator anywhere on the system?



hr

Mark Eatherton

Other things to consider....

Based on the model, there is a check valve internal to the pump. If you pop the four retaining cap screws off, you can gain access to it, and I have seen them fouled with micro chips that can make it right past the strainer.



Generally speaking, if the pump is air bound, it will make sounds like a washing machine.



I can count the number of pumps with snapped shafts that I've encountered on one finger...



In speaking with the factory, they have told me that if the pump were dropped at any point in time, it could fracture the carbon shaft, and cause it to eventually fail, or if the pump is in the wrong position in respect to the expansion tank, AND the system is running extremely high operating temperatures AND low system pressure, the impeller can create enough of a low pressure condition at the eye of the impeller that it will cause the fluid to flash to steam, thereby BLOWING the impeller off the shaft... I doubt that is your case, but something that other people should consider.



If I were you, I would do the following in this order.



1. Attempt to re-purge the system. If no go,



2. Pull the pump apart and inspect the impeller, and internal check. If the impeller is busted, replace the pump. If the check is fouled or stuck, clear it, reassemble, re-purge and see what happens.



3. Report back and let us know what you find.



ME

MarkPFalade

Answers...

Thanks ME & HR, the check valve was pulled out permanently during installation. There IS a strainer but it is after the pump per the piping diagram provided with the unit (yes, we're talking the new GAHP system I put in), Seem very quiet, no washing machine effects that I could hear. Pump draws from lowest fitting on 45 gallon tank with expansion tank on tank outlet to pump inlet piping. Again per piping diagram. The buffer tank outlet is several inches above tank bottom so picking up dirt at this stage of the game seems unlikely, but you never know. The system has been running since Feb 09 without a problem. I have pressure ports on both sides of the unit (in the pump circuit) and neither of those squeaked any air when I cracked them. Both showed the same pressure while the pump was running. They are there to sense pressure diff across the unit, which is a function of flow through the unit. You actually set the correct flow by achieving the proper delta P across the unit. There is no pressure port on the inlet side of the pump. Correct me if I'm wrong, I have never taken a Grundfos apart before. I'm under the assumptyion that I can leave the body in place and just pull the motor assembly?

Mark Eatherton

Yup....

Take your metric allen wrenches....



ME

MarkPFalade

Metric Allen wrenches?

Oh for the love of God...

lol...

Jean-David Beyer

Get 'em at Sears.

I purchased these at Sears. Craftsman. One for set for my bicycle and one set for everything else. The "bike" set has 1.5mm, 2mm, 3mm, 4mm, 4.5mm, 5mm, 6mm, and 7mm. The other set has 1.5mm, 2mm, 3mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 7mm, and 8mm. I imagine either set would work on a residential size circulator.



I have some metric socket wrenches for the W-M Ultra heat exchanger and the torque wrench to tighten them with. Those were not from Sears.

rich pickering

Regular allen wrench will work to.

But metric is nicer.



Just replaced two this week.  The impeller is made in two pieces.  It came apart.  5 others in the same system are still working. 

MarkPFalade

More thanks

I may actually have some around here. I have to look. ;-)

MarkPFalade

So,

I go back to the job, bleed the pump for sure, no luck, Pull it apart and everything looks just fine. No debris, impeller in one piece with no apparent wear or damage. Put the juice to it and it starts to run at what appears to be good speed. Hmph. Put it back together, try it installed again. Nothing. Hmph. Take the replacement I picked up apart to swap them out and notice the impellers are way different even though Mr supply guy said it was the same pump.

Take it and the original motor assy back to the supply house and put them both on the counter. Supply guy says, "Why do you want a 230V motor when the old one is 115V?" I say, "W-W-W-WHAT??!!" Sure enough, the existing motor was 115V installed and running on 230V, SINCE FEBRUARY! Seems that even though the original was special ordered 230V and I was billed for a 230V they gave me a 115V by mistake.

Having special ordered the thing I never thought to look and confirm that what I ordered was what I got. Supplier decided it was their fault and will eat the old one plus the "red label" UPS shipping so I can have it tomorrow. On the bright side, at least I know what the problem was and can rest mostly assured it won't go bad on me again for a while. "It's not easy being dumb!" lol...

Oh, I did go to the hardware store, brought the pump in with me and bought just the one exact metric allen wrench I needed. ;-)

Mark Eatherton

I don't think this thread is dead yet....

based on previous conversation, I thought the pump WAS spinning. If that is the case, it SHOULD have been moving SOME water, no?If it were a 120 V motor with 220 V being applied, it should have been spinning at 2 times its normal speed. I would have expected armature failure, but if that were the case, you would NOT have had any shaft movement when powered, UNLESS, there are other pumps in the mix...Are there any other pumps in this circuit that could cause the shaft to spin, maybe backwards???Bazarre.ME

EricAune

Mark,

Wouldn't it be likely that if the pump were to spin at say twice its normal speed, maybe that impeller was not pushing any water; just "mixing" (don't know the term I am looking for) in the housing?



Maybe the shaft is broken, it may only show with head pressure against it.

Jean-David Beyer

Cavitation

I think the word you want is cavitation.

MarkPFalade

Well,

Hard to say now. For all intents and purposes yesterday it appeared to be not pumping even though it was spinning. The greatest indication was no delta P across unit. So today I installed the replacement and still showed a no flow code on the logic board even though I now had a good delta P. Jumped out the flow switch and the unit ran ok otherwise, which now makes the flow switch suspect. Either way, the 115V motor I pulled HAD been running on 230V since Feb so replacing it was in order regardless of the rest of the outcome. It did not give the appearance of spinning twice as fast when I energized it out of the circuit where I could see the impeller. POSSIBLY (and this was the impression I got yesterday) it spun ok with no load but not when it was loaded up. Either way at least now I KNOW I have flow and I KNOW the pump motor is the right voltage. Now to change the flow switch. Add that to the 4th blown condenser fan motor in a similar unit on another job and I'm not having the best week with the Robur GAHP(s). :-(

Meanwhile all the billable time work sits and waits while I fiddle with these warrantee jobbies...sigh...

MarkPFalade

More thoughts

One thing I do notice, it now seems like it takes med speed on the 230V to do what the 110V did on low. Possibly it did just overtorque itself and spin the impeller free. The other thing is it went through the summer pumping CW so that probably had something to do with it not cooking. It did spend maybe 6 weeks of heat duty prior to that. Worked fine when I started it last Thursday, the place was heating up when I left. Saddest part is I put a Johnson S350R outdoor reset on it Thursday when I started it and I'm DYIN' to know how it works out.

MarkPFalade

Done

Replaced the flow switch and away it went. Hated to hear that air gurgling around in there again. ;-)

On the burnt fan motors, actually this is the third blown, although I'm not absolutely sure it's blown yet. So it would be the fourth motor it's had in it if I change it out. Right now all I know is I have a blown fuse. In the past this has meant blown motor. First one was definitely caused by grit from excessive dust blowing. Second time was assumed to be the same. Everything is clean now and the dust is under control, so now what?  There are 2 units there, the other one has been fine since start up.

Anyhow, thanks for the input!

LarryC

115 V motor on 230 V not equal twice as fast

Running the 115 V pump motor on 230 V does not result in the motor spinning twice as fast.  The frequency of the supply voltage and the number of magnetic poles of the rotor controls the speed of the motor.  The current in the motor windings is controlled by the line voltage, line frequency, and the rotor speed.  I bet the motor was running very hot with the overvoltage it was seeing.

MarkPFalade

My guess,

Is the startup torque would be a lot higher. It would snap up to speed much faster. If, in fact, it wasn't pumping I would guess the impeller broke loose. If I were to point my finger at what caused the flow switch to fail I would say it could have been fluttering due to poor flow from the pump which caused it to eventually fail open. Another bright side, at least I found all this now and not at 10 PM on a 0* night.