Grundfos Alpha 2 pump

[genou]

Anyone know these ? I have one as part of my CH system. Currently it has a flickering front panel, is unresponsive to button pushes and most crucially, is not pumping. I've tried power down/up to no effect. I'd be grateful for any insight into the situation.

[Mike4]

Anyone know these ? I have one as part of my CH system. Currently it has a flickering front panel, is unresponsive to button pushes and most crucially, is not pumping. I've tried power down/up to no effect. I'd be grateful for any insight into the situation.

A universally unloved pump model from Grundfos. Their first domestic, over-complicated, electronically controlled, 'energy saving' pump. Unloved because it has no mechanical method of freeing a jammed impeller and the body is about 2" taller than all their previous models meaning it often does not fit as a service replacement. The first domestic pump produced as a result of political interference in the industry.

Broadly speaking I don't know what is wrong with it other than it might be jammed. If you are of a practical bent, check the terminals with a multimeter to make sure the pump really is getting 230Vac and not some random reduced voltage, then if it is, close the isolator valves and take the motor head off. (4 x M5 set screws, 4mm Allen key). Give the impeller a spin to check it is free and if so, cut your losses and fit a new pump.

Or failing that, download the instructions for it from the net and they might tell you what the flickering front panel means. It's probably an error code.

Hope that helps a bit....

[bungeejumper]

Well, I was happy enough with my Alpha 2 pump to buy another one. Agree with Mike4 that they're over-complicated, but mine (the 15/60 model) was smooth and quiet.

Right, first question. Is it trying to go at all, and did it 'tick' for a while before it failed? The chances are that the impeller has become clogged with a bit of limescale. You might be able to break it by switching the power on and off repeatedly, so that it rattles itself free. Do this by switching the switch (or pulling the fuse in your mains system) - not by disconnecting the easy-fit plug close to the pump, because it's still live, silly.

Second question, then - How's your tap water generally? (Mine is so hard that it's got LOVE and HATE tattooed on its knuckles.) Forget what follows if not.

Third question. Before you do any dismantling, have you got a mid-sized spanner about your person? It's always worth a try to whack the sides of the pump sharply, just a few times, in the (reasonable!) hope of shattering the flake of scale. That should get you started again, although it would still be a good time to strip the impeller properly.

Soooooo, as Mike says, It's quite easy to get to the impeller once you've turned off the water at the gate valves (or, alternatively, drained the system down). You just undo the front four bolts and remove the head assembly, then whack the shaft gently sideways with a bit of wood, and then the whole front comes away, seal and all. Youtube has loads of videos of how to do it. It's at this point, of course, that you find out whether you've got watertight gate valves. or whether you've drained it down far enough.

Of course, you can still replace the damn pump with a simpler and cheaper one. My Alpha 2 was a straight swap for an older Grundfos pump - the distance between the ports was standard, insofar as these things ever are.

Best of luck

BJ

[genou]

Well, I was happy enough with my Alpha 2 pump to buy another one. Agree with Mike4 that they're over-complicated, but mine (the 15/60 model) was smooth and quiet.

Right, first question. Is it trying to go at all, and did it 'tick' for a while before it failed? The chances are that the impeller has become clogged with a bit of limescale. You might be able to break it by switching the power on and off repeatedly, so that it rattles itself free. Do this by switching the switch (or pulling the fuse in your mains system) - not by disconnecting the easy-fit plug close to the pump, because it's still live, silly.

Second question, then - How's your tap water generally? (Mine is so hard that it's got LOVE and HATE tattooed on its knuckles.) Forget what follows if not.

Third question. Before you do any dismantling, have you got a mid-sized spanner about your person? It's always worth a try to whack the sides of the pump sharply, just a few times, in the (reasonable!) hope of shattering the flake of scale. That should get you started again, although it would still be a good time to strip the impeller properly.

Soooooo, as Mike says, It's quite easy to get to the impeller once you've turned off the water at the gate valves (or, alternatively, drained the system down). You just undo the front four bolts and remove the head assembly, then whack the shaft gently sideways with a bit of wood, and then the whole front comes away, seal and all. Youtube has loads of videos of how to do it. It's at this point, of course, that you find out whether you've got watertight gate valves. or whether you've drained it down far enough.

Of course, you can still replace the damn pump with a simpler and cheaper one. My Alpha 2 was a straight swap for an older Grundfos pump - the distance between the ports was standard, insofar as these things ever are.

Best of luck

BJ

When powered on it makes no noise at all. All that happens is that the panel lights up , but is flickering at about 60Hz, and does not respond to the control button. There's no error code that I can understand as such - the manual says these should be numeric, not flashing lights. I've tried powering up/down completely , and also switching demand on/off ( does the pump see any difference here in trying to spin up ? )

The water here is completely soft, and the circulating water is Fernoxed to buggery. I have tried a mild couple of whacks, but I don't really have a sense of how hard I should be trying to hit it.

I can't see the relationship between a flickering display and a stuck impeller. Is not the power state that is flickering - it is the whole display. My gut feel is that it is an electrical failure in the pump.

[bungeejumper]

I can't see the relationship between a flickering display and a stuck impeller. Is not the power state that is flickering - it is the whole display. My gut feel is that it is an electrical failure in the pump.

LOL, nor could I, but that was what the user instructions said was probably the cause. Non-behaving buttons and all...(If you've lost your instructions you can get another set online.) Counter-intuitively, it turned out to be right - in my case, anyway.

It's a cost/effort toss-up between having a go and getting a plumber in. But if you're buying your own new pump, shop around, The Alpha 2 retail prices vary hideously, between £130 and £300 the last time I went shopping for one.

Best of luck, anyway

BJ

[genou]

You just undo the front four bolts and remove the head assembly, then whack the shaft gently sideways with a bit of wood, and then the whole front comes away, seal and all. Youtube has loads of videos of how to do it. It's at this point, of course, that you find out whether you've got watertight gate valves. or whether you've drained it down far enough.

Gate valves are tight. One drips when closed, but happy when re-opened. God knows why there is so much travel on them. Got the head off and the impeller was free spinning. Put it all back, and powered it up, and hey presto - the panel flickers at around 60Hz, and the pump runneth not.

https://www.youtube.com/watch?v=ZUNJd06iyWU

It's a cost/effort toss-up between having a go and getting a plumber in.

New pump time I think. Thank you for your help.

[Mike4]

You just undo the front four bolts and remove the head assembly, then whack the shaft gently sideways with a bit of wood, and then the whole front comes away, seal and all. Youtube has loads of videos of how to do it. It's at this point, of course, that you find out whether you've got watertight gate valves. or whether you've drained it down far enough.

Gate valves are tight. One drips when closed, but happy when re-opened. God knows why there is so much travel on them. Got the head off and the impeller was free spinning. Put it all back, and powered it up, and hey presto - the panel flickers at around 60Hz, and the pump runneth not.

https://www.youtube.com/watch?v=ZUNJd06iyWU

It's a cost/effort toss-up between having a go and getting a plumber in.

New pump time I think. Thank you for your help.

Ok a couple of things then:

1) The Grundfos UPS2 15-50/60 was the superseding model and suffered from failure of the electronic speed sensor. Here, it would spin for half a second then stop, re-initilise itself then spin for half a second again. Very confusing to plumbers as it would make the pipe get hot but the flow was only about 5% of what it ought to be so nothing worked. I mention this for completeness, and wonder if something similar could be happening with the OP's Alpha 2.

2) If the OP buys a new Grundfos in particular, they will probably end up with a Grundfos UPS3 15-50/65 and although it looks completely different, the dumb cast iron back body with the pipe connections is the same as the Alpha 2, meaning there is no need to disturb the potentially troublesome big nuts connecting to the pump valves. Just take the heads off both the old and the new pumps, them bung the new head onto the old casting body still in position on the pipes. Easy as Pi.

The UPS3 will be over £100 though, and there are a number of 'me too' cheapo pumps on the market costing half that, should the OP have lost confidence in the market leader. None of these that I've discovered has a pump head interchangeable with the Grundfos though. They never quite fit. I dunno if the new kids on the block are missing a trick, or whether it is deliberate because Grundfos perhaps have copyright on the back body design/dimensions.

[genou]

Very confusing to plumbers as it would make the pipe get hot...

Trust me, if there was any heat anywhere in this house I would know. The flow switch sees nothing, and the boiler remains schtum. The warmest room is elsewhere in the cellar, where there is a freezer and fridge-freezer. It is, to my current view, positively cosy. We had baked potato as a side tonight, cos that meant running the oven to warm the kitchen to eat in.

2) If the OP buys a new Grundfos in particular, they will probably end up with a Grundfos UPS3 15-50/65 and although it looks completely different, the dumb cast iron back body with the pipe connections is the same as the Alpha 2, meaning there is no need to disturb the potentially troublesome [**] big nuts connecting to the pump valves. Just take the heads off both the old and the new pumps, them bung the new head onto the old casting body still in position on the pipes. Easy as Pi.

It's an attractive solution. I hadn't noted the detail that the current pump is auto-adapting, but I assume that is par for the course now. Do they all share the same plug/connector to attach to the controller ?

We are now committed to going to the MiL's while a plan is formed, so that's a step in some direction or other.

{**] I have chatted to various fitters as they got out bigger and bigger wrenches to stop these things dripping. I think it would take a controlled explosion to release them now.

[Mike4]

It's an attractive solution. I hadn't noted the detail that the current pump is auto-adapting, but I assume that is par for the course now. Do they all share the same plug/connector to attach to the controller ?

I admire your optimism but do have a guess. You'll probably be right!

[bungeejumper]

I hadn't noted the detail that the current pump is auto-adapting, but I assume that is par for the course now.

No real idea, but I'd doubt it. Mike4 will know more than me, but as I recall, these self-regulating CH pumps were a well-meaning Brussels fantasy about improving Europe's energy efficiency - and unlike some other good euro ideas, this one didn't stack up. Certainly, pumps like the Alpha 2 could save you about £20 a year on your electricity bill - but if the price of that was that your over-complicated pump needed replacing every five years, then you weren't going to feel the financial benefits.

I never got very far into the theory of these innovations, but as I understand it, the idea is that they vary their power consumption automatically according to how many radiators you've got turned on - or rather, according to the amount of work that the pump is being asked to do. On mine, that can mean that the consumption figure on the display varies between 15 watts and 40 watts. (We have 17 rads and a fairly extensive system of pipe runs.)

In practice, the Alpha 2 gives you a choice of four self-regulating speed settings, plus another three fixed speeds exactly like the ones that cheaper "normal" pumps have. I experimented at length in search of the ideal settings, and I never noticed any real difference at all between them. All I'd got for my money was a load of extra electronics. Still generally satisfied with the pump, though.

BJ

[stewamax]

...there is no need to disturb the potentially troublesome big nuts connecting to the pump valves. Just take the heads off both the old and the new pumps, them bung the new head onto the old casting body still in position on the pipes. Easy as Pi.

Well said. If they are like the older Grundfos models, you just need a large Allen key. The head assembly and mating back block are accurately machined and seal together well

In practice, the Alpha 2 gives you a choice of four self-regulating speed settings, plus another three fixed speeds exactly like the ones that cheaper "normal" pumps have.

The older Grundfos models also have a proportional pressure mode that works well - particularly in the summer when most radiator TRVs are almost shut and the pump slows down to near silence except when there is a demand for domestic hot water (DHW).

Note however that all the domestic pumps I have looked at deliver either a fixed head* (when on constant flow or constant speed), or an increasing head (when on proportional pressure) as DHW or CH demand (i.e. flow) increases. This makes it impossible for external pressure-driven automatic bypass valves (ABVs) to work as they rely on the head falling as demand increases. Strange but true; if anyone doubts this just see the manufacturers' published 'head vs flow' curves.


* - from no-flow (when all TRVs are shut and there is no DHW demand) to almost full flow (when all TRVs are open and someone is having a bath)

[88V8]

It all seems a ghastly overcomplexification, for something that uses... what.. 100W?

When we had ch, as I designed and installed the system I just chose a pump to provide the necessary volume and head.
The pump was a can't-remember-the-make four-speeder... in the winter I ran it in 3rd gear, in summer when it only had to pump the HW, I ran it in 1st.
There was also an always-on loop through a towel rail to ensure that the pump was never dead-ended.

That pump ran from 1982 to 2012 when we sold the house and for all I know is still working.

Complexity for its own sake... so typical of modern appliances.

V8

[9873210]

It all seems a ghastly overcomplexification, for something that uses... what.. 100W?

When we had ch, as I designed and installed the system I just chose a pump to provide the necessary volume and head.
The pump was a can't-remember-the-make four-speeder... in the winter I ran it in 3rd gear, in summer when it only had to pump the HW, I ran it in 1st.
There was also an always-on loop through a towel rail to ensure that the pump was never dead-ended.

That pump ran from 1982 to 2012 when we sold the house and for all I know is still working.

Complexity for its own sake... so typical of modern appliances.

V8

Requiring an always-on loop is also a form of complexity.

From an industrial controls background what always amazes me about plumbing is you have multiple micro controllers exchanging information using pressure surges in a hydraulic system, instead of simply using CANbus or similar. Talk about your complex ad hoc bodge.

Industrial controls did away with that in the last century. The only controls not connected to the CANbus are simple mechanical emergency devices which never operate unless something has gone terribly wrong. It's not complexity for its own sake, its complexity to lower costs, perform better, last longer, allow single point remote diagnostics, ... .

[csearle]

...

I think the first CAN bus chipset was available in 1991. These plumbing systems were around way before that. Old habits die hard.

C.

[genou]

For those who appreciate closure in these things, the pump has indeed been replaced with a Grundfos UPS3.

System has been up for ~ 20 hours, and we have reached the giddy heights of 16.8C.

Thanks to all.

[servodude]

...

I think the first CAN bus chipset was available in 1991. These plumbing systems were around way before that. Old habits die hard.

C.

Not just plumbing!

I've worked on a wind turbine installation (adding third party telemetry) where the output of the multimillion dollar turbine was communicated to the multimillion dollar grid feed in system through one bloody 4to20mA input
- I had my hands on more info from both sides and all we were doing was passing it back to the community shareholders (and running a sign that showed the power being generated)
- they mostly used it to know when the 4to20 connection failed to "send someone round"

-sd

[csearle]

...through one bloody 4to20mA input

Am I right in thinking that the advantage of using a varying current is that it can be used over long distances, the current being the same everywhere? Also I imagine it is quite good at noise rejection? C.

[servodude]

...through one bloody 4to20mA input

Am I right in thinking that the advantage of using a varying current is that it can be used over long distances, the current being the same everywhere? Also I imagine it is quite good at noise rejection? C.

yeah for a single analog signal using a current loop is a great (if abstract) way to do it
- and there's a convenience in development of not being able to tell that someone has attached the "correct" source/sink (that's not such a great thing once installed)

-sd