Grundfos Pump working intermittently

Calibos

Completely new Heating and Plumbing system installed 6 years ago in our Victorian renovation. Floors were lowered at the back of the house for an Attic conversion. The Bathroom in this Attic conversion is thus almost on the same level as the Cold storage tank in the unconverted attic space. The Showerhose Head hangs higher than the cold storage tank.

Thus a Grundfos 1.5bar Amazon Universal Negative Head Dual Hot/Cold pump was installed. Feeds the Sink Taps, Toilet Cistern and Shower in this attic conversion bathroom.

Link to Product Page

I understand that this is a Rolls Royce of pumps with Brass Impellers and Housings.

The pump stopped working 100% reliably a few weeks ago after 6 years of daily usage. I found a thread here on boards from 2014.

http://www.boards.ie/vbulletin/showthread.php?p=89277652

I found that water still flows slowly from the tap (or showerhead when its unhooked from its wall mount and left hanging with the head lower than the level of the cold storage tank) even when the pump has stopped working. This to me says that the filters of the pump are not blocked. After reading that thread, I left the sink tap on so that there was a call for water to the pump and then I gave the brass housings on the pump a few taps with a hammer and tried switching the pump on/off a few times at the power outlet. Not sure the hammer tapping did anything but the On/Off cycling did seem to work and the pump comes to life. The pump seems to seize again when its been left about 24 hours unused. The On/Off cycling has to be done again to get it working again.

Would I be correct in thinking that this sounds like hard water mineral build up on the brass impellers/housings. So like that chap in the 2014 boards thread, I probably just need to open up the impeller housings and clean the housings and impellers. Do I just do what he did with emery paper and brasso or is there a product to buy that would do a better job (submerge and soak the impeller and housing?? Calgon??

Has anyone worked with these pumps. Is it just a push/compression fitting where the flexible houses join to the pump. Do I switch off at the isolation switch, disconnect the electrics in the pump electric box. Close the hot and cold inlet valves and with bucket and towels handy, push down on the collets and pull the flexible hoses out of the pump? Remove pump and dismantle the brass housings.




Or am I barking up the wrong tree and it could be an issue with the flow sensor or Negative Head pressure vessel like in this 2011 boards thread.

http://www.boards.ie/vbulletin/showthread.php?t=2056277556

What can I do to diagnose the flow sensor or pressure vessel??

K.Flyer

From what you describe, I would be looking at the pcb and capacitor first.
Both can sometimes be jostled into action with the electric being switched on and off.
Please leave the hammer in the tool box, hitting it with a hammer, even tapping, especially the pump heads, will only cause damage.
Delayed starting is a very common problem with those Grundfos Neg Head pumps, but fitted with different components usually solves the problem.

nmacc

Definitely agree with K. Flyer.

Your pump has three switches, two flow and one pressure. If you turn on both taps and the shower is below the level of the tank, then all three switches should be in play, so if it won't start it's most likely the circuitry. If tapping it worked then it could be a relay, but there's no way of knowing without testing it.

if you're in Bray then it's not lime. Except for a few folks on their own wells in the Windgates area, the water in Bray is soft.

Calibos

K.Flyer wrote: »

From what you describe, I would be looking at the pcb and capacitor first.
Both can sometimes be jostled into action with the electric being switched on and off.
Please leave the hammer in the tool box, hitting it with a hammer, even tapping, especially the pump heads, will only cause damage.
Delayed starting is a very common problem with those Grundfos Neg Head pumps, but fitted with different components usually solves the problem.

nmacc wrote: »

Definitely agree with K. Flyer.

Your pump has three switches, two flow and one pressure. If you turn on both taps and the shower is below the level of the tank, then all three switches should be in play, so if it won't start it's most likely the circuitry. If tapping it worked then it could be a relay, but there's no way of knowing without testing it.

if you're in Bray then it's not lime. Except for a few folks on their own wells in the Windgates area, the water in Bray is soft.

The Showerhead is mounted above the level of the tank. So you are saying the next time it seizes I should unhook the showerhead and let it hang with the head now below the level of the tank and open up our mixer tap full. If the pump doesn't start then its definitely the PCB?? Will do it again but I think I actually did just that to diagnose that the filter had to be OK because there was low pressure flow from the tank through the seized pump. So its deffo looking like the PCB then?

I'd read about the light hammer tapping in the old boards thread. However the pump didn't start with the tapping, it started after a few on/off power cycles so I guess that means it wasn't a relay being jostled bring the pump back to life. That was the one and only time I tried the tapping. Won't do it again

Wasn't sure about Water Hardness. A google showed me This Thats why I thought it was hard.

Right so, if its looking like the PCB then am I right in saying that I just need to Order Part 13 (GRUN-EA006 Grundfos PCB - Brass Twin Negative Head EA006) from here: http://www.showerdoc.com/grundfos-amazon-pump-negative-head-shower-spares

GBP£36.22 (€48)

Is there anywhere else you guys would recommend getting the spare parts instead?

I'll be a happy chappy if this resolves the problem for €48 Coulda been a lot worse if the whole pump needed replacing at nearly €600 :eek:

hatchman

I would be thinking the capacitor would be what you need to change rather than the PCB. I'm no expert but they are usually the problem linked to the symptoms you describe.

K.Flyer

If a pump is on the original pcb and capacitor, I would usually change both of them at the same time. As they age the pcb relays wear out and will eventually become unreliable, and the capacitor will have starting issues as well.

Calibos

So its part 14 from that page?

http://www.showerdoc.com/grundfos-amazon-pump-negative-head-shower-spares

I'd just need to check whats printed on the currently fitted Capacitor to find out which one to order?

Calibos

Intended to order the PCB and Capacitor tomorrow. For my testing I've been turning on the tap and if the pump didn't start after a few seconds I knew I had to do the on/off cycle. Tonight I flushed the toilet and the cistern didn't fill as the pump hadn't started up as usual. I couldn't immediately get to the pump straight away to do the on/off cycling but could hear the pump motor hum. I knew this meant the casing would be hot to touch and there would be a smell when I made it over to the pump. However after about a minute the pump did fire up by itself before I had a chance to do the on/off cycling.

So does the fact that the pump did fire up by itself without the on/off cycling albeit after a full minute change the diagnosis of PCB/Capacitor to flow sensors or anything else or are we still going with PCB/Capacitor?

K.Flyer

If there was a flow of water and the pump was making a humming sound, that is indicative of a capacitor problem.
Only other reason for a humming sound is a seized motor, but a seized motor rarely will start up, and if it does it then tends to be quite noisy.

Calibos

Cool. Right so. I'll isolate the power to the pump and pop the lid off the PCB box and inspect the capacitor to get the number off it and then order a new PCB and the correct capacitor from that UK site I linked to. (unless you recommend a different parts supplier)

Calibos

Decided in the end to just order the capacitor and take the extra €5 shipping hit and delay if it turns out I needed a new PCB as well.

Capacitor arrived in the post today. Before I fit, is there any precautions I need to take other than turning off the power to the pump at the wall switch?

K.Flyer

Nope, other than isolating electrics and they are the same uF rate, just make sure to connect back up the same way. Take a pic as a reminder just in case.

Calibos

How do I remove the capacitor cables from the connection block on the PCB. I had just assumed pushing a small jewelers flat head screw driver in to the slots would release a spring clip holding the wire or somesuch. No joy so far. Is there a trick to it or am I not pushing the little screw driver in hard enough

K.Flyer

Does the new capacitor not have spade connectors like the old one?

Calibos

K.Flyer wrote: »

Does the new capacitor not have spade connectors like the old one?

It does. I tried pulling on them and they didn't budge so I decided not to force them off. So it's safe to give them a good tug then?

The other thing was that with the print on both capacitors facing the same way, the live and neutral wires were on the opposite spades. Does this reverse of polarity not matter? [Edit] Actually scratch that, when I pull the spades off the old capacitor I just push them onto the matching spades of the new one and it's irrelevant what spades the wires on the new capacitor were attached to.

Btw thank you so much for all the help in this thread and especially this late tonight!

K.Flyer

And after all that... is the pump now working

Calibos

K.Flyer wrote: »

And after all that... is the pump now working

Needed a vice grips to pull the buggers off the spades.

So far so good. the pump certainly sprung into action as soon as I opened the tap. However it has sometimes been working without the need to power cycle, then not work 20 minutes later etc. I'll know for sure, if it works first time everytime over the course of the next day or two.

Thanks for the help. At the beginning I was worried I might be needing a new €600 pump but as it turned out your recommended fix only cost me about €20 incl P&P

SmallBalls

K.Flyer wrote: »

Delayed starting is a very common problem with those Grundfos Neg Head pumps, but fitted with different components usually solves the problem.

Pressure switch?

I know the switches fitted can be adjusted but even adjusted to their max I've still had problems on jobs with the delayed starting, really annoying. I've gone back to fitting Stuart Turner now for neg head pumps because of this.

K.Flyer

SmallBalls wrote: »

Pressure switch?

I know the switches fitted can be adjusted but even adjusted to their max I've still had problems on jobs with the delayed starting, really annoying. I've gone back to fitting Stuart Turner now for neg head pumps because of this.

That is the reason I dislike the Neg Head Grundfos pumps and stick to the Stuarts. I've spent too many hours on my knees adjusting those damn pressure switches only for it to end up being a complete waste of time.
I have been assured of new aftermarket switches available solving the problem and I will be picking up a set to have at the ready for the next Grundy I get with that issue.

Calibos

Looks like the capacitor did the job alright. Pump fires up first time everytime since I fitted the new capacitor.

Thanks again!!

Dtp1979

K.Flyer wrote: »

That is the reason I dislike the Neg Head Grundfos pumps and stick to the Stuarts. I've spent too many hours on my knees adjusting those damn pressure switches only for it to end up being a complete waste of time.
I have been assured of new aftermarket switches available solving the problem and I will be picking up a set to have at the ready for the next Grundy I get with that issue.

I'm glad. I thought I was the only one!