Is my Grundfos Good or Bad?

I dropped my Grundfos MQ3-45 off at the "Authorized Grundfos Service Center" for diagnosis a few weeks back. Long story short, the Service Manager says the reason why I couldn't get it to work was because I was connecting a pump wired for 230V to 115V, and that it tests good at his shop.

My primary concern was that the Logic Board was good. (They cost several hundred dollars to replace.) The pump was new 8 years ago, and was only used about 5 times at the cabin in the first year, before it sat unused for the next 7 years, so I would expect it's wear to be very minimal. Also, I have 2nd hand information that when it was used, it was able to lift water from a shallow well (actually a creek) about 32 ft. and provide adequate water to the cabin.

My concern is that it took several weeks to get the Service Center to even look at the pump, then a couple more weeks to finally get in contact with the Service Manager. It felt like they didn't want to do the work, and then when they "did" the work, it was a superficial job and
'push it out the door". And I need to know that, if I transport this pump 1000 miles to Ruidoso and install it, that it is going to provide adequate water.

The Service Manager said that they tested it and it produced about "42 pounds of pressure". I need to know what this means and/or what he meant, because when I went to look up the Grundfos pump's specs, it gives two different pressure specs and I don't know what they are, and which one he is referring to with his 42 psi number.

The Specs mention "109 psi" which as "output pressure" would be wonderful, and it also mentions 40 psi, which might be the Service Manager's number, but I have no idea what that is. There's words being used I don't understand also, like "static", "suction lift", "head", etc...

My concern is that if the pressure switch is preset to turn on at 30 psi and turn off at 50, but never develops more than 40, the pump will never turn off. He said it would turn off when the pump sense that water was no longer flowing, but the whole deal feels "hurry up" and I need to be able to rely on this information, as it's going 1000 miles away (literally) and the nearest Lowes is 150 miles away.

Another concern is, when I was trying to figure out what was wrong with it, I disassembled the jet-pump side of the pump. I THOUGHT I put it back together again correctly, but many of the parts looked exactly alike and if they are not, I might have mixed them up. So again I'm wondering if the 40 psi number quoted could be something closer to the 109 psi, if I had assembled the jet pump correctly. I'd hoped the Service Center would have disassembled the Jet Pump (for inspection) and then reassembled it, but I have almost no faith that they did anything but the bare minimum to get me to go away, and I need reliable information for the reason stated previously. The time to get this thing fixed is now, not when I'm in the middle of nowhere with no water or access to repair facility, etc...

Any help with this would be greatly appreciated, and thanks in advance.

PS
I'll post this on the chance it is useful. It looks like the site is Canadian. I don't know if that matters one way or the other, but I thought I'd mention it.

http://www.grundfos.ca/web/homeca.nsf/Webopslag/ALEE-64EH2U

Probably the service manager wasn't the one that actually tested the pump. It's a he said, he said situation. A qualified service technician could have tested the pump in just a few minutes. Manufactures and service centers want to sell pumps not service them. I too have concerns about the test. By the diagram and model http://www.us.grundfos.com/Web/Download.nsf/Pages/6A0893C7B967963088256EDF00546536/$File/L-MQ-PG-001.pdf it tells me that the pump is a 3 stage 45 psi pump but I'm not sure. Grundfos makes good pumps but variable flow pumps of any make are a nightmare. Sorry I can't be of more assistance.

That is one of the least dependable pumps made. See this link for a picture.
https://terrylove.com/forums/showth...and-tank-combo-replacement&highlight=dumpster

Please note the snip of the specs above.

What does "inlet pressure" mean? Is this "suction" ?

What does "System Pressure" mean? Is this output pressure?

Seems like inlet pressure would be a negative number.

Any idea how the Service Manager's "42 psi" number might fit in here?

Thanks again.

BillyJoeJimBob said:

What does "inlet pressure" mean?

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Those pumps are often used for boosting existing pressure. System pressure is the max the casing can sustian. It is not what the pump is capable of producing.

LLigetfa said:

Those pumps are often used for boosting existing pressure. System pressure is the max the casing can sustian. It is not what the pump is capable of producing.

Click to expand...

Thanks! Okay I get that. Then what is "inlet pressure"? Is that a negative pressure, like "suction" or "pulling power" or what? I'm still trying to reconcile what the Service Manager said and what the Grundfos specs are.

Is this the same thing as "output pressure"? He said that it developed about 42 psi. in the test. I assume the test was just dropping a suction pipe into a bucket of water.

If it only outputs 42 psi, how is it going to turn off at 50?

An Update

Well, I finally broke down and called the Grundfos Repair place and talked to a lower-level Tech who was a lot more informative.

He said that 42 psi was output pressure from a "flooded suction pipe" (no lift) and that that was normal for that pump. So that was the answer to my main question. If it used to be able to provide adequate water (8 years ago) and it's working normal now, then I think it's safe to assume it will be able to provide water again when we go back.

But now I have another question.

The Tech also said that these pumps were commonly used as Booster Pumps. I'm wondering if it might be possible to install a second pump and run the two in series with each other.

Is this commonly done? Is this a dumb idea?

Thanks in advance.

BillyJoeJimBob said:

Thanks! Okay I get that. Then what is "inlet pressure"?

Click to expand...

The inlet pressure is the maximum allowable positive pressure when the pump is used as a booster.

When the pump is used to lift water from a depth (negative pressure), I doubt it would ever produce 50 PSI but as the tech said, it should sense a loss of flow and turn itself off. As for the 2nd hand info you got about it lifting 32 feet, that has got to be BS. If you want any kind of pressure at all, that pump will have to be down at the water's edge.

BillyJoeJimBob said:

But now I have another question.

The Tech also said that these pumps were commonly used as Booster Pumps. I'm wondering if it might be possible to install a second pump and run the two in series with each other.

Is this commonly done? Is this a dumb idea?

Thanks in advance.

Click to expand...

How about the idea of connecting two pumps in series ?

BillyJoeJimBob said:

How about the idea of connecting two pumps in series ?

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That would work, but makes for a complicated control set up. If your going to get another pump anyway, get one big enough to do the job by itself. Preferably something dependable without that "electronic board" control.

valveman said:

That would work, but makes for a complicated control set up. If your going to get another pump anyway, get one big enough to do the job by itself. Preferably something dependable without that "electronic board" control.

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I appreciate the answer. At this point, we are spending a lot of money in a bunch of different places, all of the expenditures are critical. I'm just trying to get the situation up to "good enough" and can improve it from there. Long term, I agree that either getting a larger pump is a better idea, but I just need something to get me through the next few months. I have a (probably) working Grundfos, and a Gould with a cracked pump housing. I could buy a cheap pump a Lowes again (I returned the last one.).

The control situation was also a concern. Can you run two pumps from one control switch?

BillyJoeJimBob said:

The control situation was also a concern. Can you run two pumps from one control switch?

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Yes but probably not the MQ. Put the Goulds pump to running with a regular 30/50 switch, and let the MQ add it's 40 more to that.

valveman said:

Put the Goulds pump to running with a regular 30/50 switch...

Click to expand...

The max in for the MQ is 44 so maybe 20/40. With another 40 added by the MQ, you could max out 80 PSI.

The Final Verdict

Came back to SA on Monday from a week in Ruidoso. Installed the Grundfos and it worked beautifully.

I would like to thank everyone for the help and advice. Most particularly, the advice on how to convert the 115 VAC to 230 VAC. I purchased the circuit breaker in Alamagordo when I bought a 38 gallon lowboy hot water heater.

On day 2 I installed the Grundfos. There was already a 230 circuit there, and it worked perfectly. Develops 42 psi after pulling the water up about 30 feet from a catch basin. Flow at the kitchen faucet (the farthest point) is low, but the flow at the tub (the closest point) is HUGE. Didn't measure it, but it was at least 10 gpm. There may be some kind of blockage in the line to the kitchen. I am not going to worry about it, but am considering converting all the PVC and CPVC to PEX at some point. (That will be another thread.)

On day 3 I installed the Hot Water Heater. That went in like a dream. Hurt my back getting it out of the SUV. That was the only casualty, but it got better in a few days. Lol, I changed-out the circuit breaker while the panel was live. I guess that was the only interesting point. Connected the wires to the circuit breaker, then snapped it into the panel. Pucker factor was a bit high, but I've been stupid before so I had experience on my side.

So we spent the rest of the week cleaning mouse poop and burning pine needles. And we could take a hot shower anytime we wanted. That was absolutely wonderful. And I owe all of it to the people here. My most sincere thanks.

~ BillyJoeJimBob

Thank us by buying a backup pump for when that known trouble maker goes out again.

ballvalve said:

Thank us by buying a backup pump for when that known trouble maker goes out again.

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This pump seems to be special in that it is able to draw water up about 30 ft., and is still able to produce 42 psi. It's called a "Jet Pump". Can all jet pumps do this? What would be a good replacement for this pump, or preferably something that has even better output?

A regular "Jet Pump" would be better. You can get larger horsepower like 1.5 or 2 HP, which will pump more water. Look at brands like Goulds, F&W, AY McDonald, Sta-Rite, etc.

valveman said:

A regular "Jet Pump" would be better. You can get larger horsepower like 1.5 or 2 HP, which will pump more water. Look at brands like Goulds, F&W, AY McDonald, Sta-Rite, etc.

Click to expand...

What is the difference between a "regular" Jet Pump, and this particular Grundfos? I've had it apart and have seen the logic board, the air bladder thing, the plastic impellors in the pump housing, etc... I know everyone hates it for being unreliable, but it looks high-tech. Sort of "all in one", I guess. Self-priming; the logic board has some kind of "timing" routine that does the self-prime. That seems like a desireable feature. Is there a more reliable equivalent? Any particular model? I'll start posting specific models and asking about each, if that's best.