Replacing Grundfos 15-60 selectric pump

[spaarks]

If it works on HW independently then surely there can't be a blockage?
I suppose it would be possible (if unlikely) for an MV to be somehow stuck closed even when the indicator shows open (I've seen it happen in hydraulic valves). Try giving it a light tap (no, not with a big hammer!). I believe some valves can be operated manually.
If it was mine I'd change out the MV at this point.

 

[Bartdude]

It does sound like a problem with the motorised valve. I don't like using a 3 port valve with bigger systems,I've always thought that 2 port valves provide better flow.

 

[spaarks]

Yeah, I've been told by several people that the 2 port (S system?) are more reliable as well.

Nerobi10 could it be your pump is just jammed (maybe by some crud that moved when you bled the rads). The pump is quite easy to dissemble (or hit it with a hammer!). The whirring noise could indicate an electrical problem such as a faulty capacitor.

The flow and return pipes coming out of your boiler should be at different temperatures - I think 11C, which you will be able to feel by hand. If they are the same temperature it shows there is no flow.

 

[donkeeboy]

Heres another thing - I just took MV off and I noticed (whilst CH+HW turned off) that it still continued to make a very quiet electrical whirring noise - even though it did not need to do anything. Is this normal? It sounded like one of those cheap electrical clocks whirring away. Let me be clear though, this is NOT the normal noise it makes when motor is movng it to a new position - that is much louder and more noticable. Its not trying to move to new position when off, just whirrs away quiety, maybe its normal or maybe it a sign of fault.

Incedentally, with MV off, I could move valve very freely and easily with my fingers, does not seems to me stilcking at all. It aonly moved a very small amount though - like an 1/8 of a turn, but I guess thats normal. It felt right.

Thats interesting what you gues say about the S plan being more reliable - too late for that now for me though Its all been redone.

Sparrks, yeah I feel the same about the blockage too, it dont ring true since it works fine most of the time. I just wondered if some crud was going around and just causing blockage intermittently as it circulated. Prob not - basically what it boils down to is that I can drain the system for free before I replace the MV which is gonna cost money, so I may as well it in that order.

Plan - drain system (too cold today), presume it will be no different, dissassemble pump and clean it inside, prob not that either, replace MV. If no different after this then I will be doing an E9 trip out myself as I wont be too pleased!

Thanks for the help, will update progress in due course. - If this quiet MV whirring whilst not in action is indeed abnormal be good if some one could tip me off. Cheers.

 

[raymondo68]

Hi Donkeeboy

Having read all threads I suspect that this is a problem with the MV. I would be interested to know the make of the MV and the size of the pipe that feeds it from the boiler i.e. the main flow. It sounds as though the MV is not responding correctly under a certain set of circumstances.

You can buy a replacement head for most MV's and make the change without draining down, however I would strongly recommend that you get the wiring configuration checked when the change is made.

Incidentally on a system this size I would normally expect to see an S plan system as mentioned earlier, and it is not too late to make the alterations.

Good luck

Raymondo

 

[donkeeboy]

Thanks Raymond,

Its a Drayton Mid position actuator model MA1. Its only 3 years old.

I hear what your saying about the S-plan, several people have said that. I assumed it was all tickity-boo as corgi guy did it all 3 yrs ago bit of a shame that. I think I will look into changing it over in the summer, dont want to do any serious work on it in winter.

You know, thinking about this S-Plan a bit more, some one said it will give better flow than my existing Y-plan. Is it significant?

Because before I had all this work done 3 yrs ago, I had a beastly cast iron 48.5KW behmoth known as a Ideal Concorde. Must have been 40 years old. Plumbers came in and looked at in shock when i wanted new system quotes! Back then, I always called it 'the death trap', but since upgrading I know refer to it retrospectively as 'the good one'! I was prob to hard on the thing when we had it. My new system is OK, but its so much more unreliable even tho its a good boiler, just so much more to go wrong nowadays, some of which is very much for the better im sure.

ANyway getting to the point, the old boiler pre-historic though it was, could really heat this place up like a sauna if I wanted to. And its a big place, and an old place - not very well insulated. It was 48.5KW but 40 years old min, and poorly maintained I would guess. I never serviced it for its last 10 years anyway. So I was prob not getting nothing like 48.5KW of power out of it. The new boiler is 40.8KW, and basically it just dont get the house as hot has the old one - nowhere near, absolutely nowhere near at all. There is nothing wrong with it, it just dont have the clout of the old one.

So if I changed to an S-Plan, would I expect any better performance out of it all? I do not know what configuration the old boiler was setup in - it was all hidden behind a mnass of cast iron.

 

[raymondo68]

Thats interesting donkeeboy

The reason I asked about the pipe size between the boiler and the valve is that a normal 22mm 3 port valve is really only suitable for systems upto about 18Kw. I think your MA1 is probably 22mm and is therefore in my opinion too small to really allow adequate flow, others are free to comment???

The MA1 valve has a gearing system that will falter when it starts to wear. If you can upgrade to 2 x 2 port Honeywell valves (S plan) I think you will notice a difference. Also 28mm primary flow and return pipework would not be out of place on a system of that size.

The reason your old system appeared to perform better is that it is unlikely that there were any motorised valves. The hot water was probably provided by a gravity circuit and the heating by a completely separate circuit with its own dedicated pump. Again I would be interested in the views of some of the more experienced guys.

Incidentally Corgi Registration or Gas Safe Registration as it is now lets you know that the fitter is qualified to install the boiler safely in terms of connection to the gas service and the removal of flue gases. Efficient central heating design is another thing altogether especially as your system is on the large side, many rule of thumb calculations do not work for larger installations. That said, your system used to perform well and there is no reason why it should not do so again.

Good luck

Raymondo

 

[donkeeboy]

Raymond,

Thanks very much indeed. Thats very interesting. Yes its currently 22mm pipwork, sry I forget to say.

Yeah before there was nothing much there, just the boiler, electrical programmer, and a pump. That was it. Pretty sure the was no MV.

I just looked, and indeed where the new 22 pipes are fitted, they are fitted onto the remainder of the old pipes, which are chunky - looks 1 inch pipe to me easy, maybe 1.5 inches.

Im def going to get onto the S-plan in the summer. I never realised any of this until now. Cheers

 

[mfgs]

Bit of a weird problem as a 3 port is always either open to one circuit or both. The noise you are hearing sounds like a dodgy motor but wouldnt explain it overheating and locking out as it shouldnt be a closed circuit at any time unless the ball has picked up some crap on it? Even if it was partially blocked the boiler should modulate enough in time for it to not lock out that quickly.

The F+R should definately be in 28mm with a 40kw boiler aswell which wont be helping matters.

 

[donkeeboy]

Hi Guys,

Just thought I would update you all on how I have been getting on with this strange problem. Something funny happened yesterday!

Yesterday, I intended to replace the MV. But first I took the pump head off to see if its got any crud in it - it didnt, it was totally clean.

Then I took the MV actuator off, incidentally, I turned the valve with my fingers (this time with the power off of course due to disconnected pump) When I did this it did not move freely like it did before - if flicked from left to right with a far amount of force, and made a pretty loud clunk noise whenever I did it, which was a few times. Last time I did this (with power on) the valve spindle moved freely with no clunking, and I could move it wherever I wanted (eg in the middle), without it clunking straight to one side or the other.

Impiortantly one thing thing i noticed, once the actuaator was loose - it rattled badly - there was something inside it loose, and something not too small too, which really tattled about when you shook the actuator. Im thinking now whatever was rattling loose inside the actuator was impeding it from working properly.

Then I went down the plumbers merchant for a new actuator (Drayton MA1 3 port). Well it was well too pricey! I seen on online for much much less, I figured it would be more down the merchants, but not like double the price. So in the end, I left it, and came home and put the old actuator back on. (I had not removed any wiring).

So heres the funny bit - after this (effectively doing nothing, just removing existing parts, and put same parts back) it seems to be working fine! You may remember I caan recreate this problem now by doing a specific sequence of events, I tried many times yesterday to get it to trip out (its not 100% that it does it everytime) but I did not trip out once! 10-15 times, nothing. Although in the yest morning before I did the above, I tried it once and bang - 1st time it tripped out.

How strange! So basically, I do not think disconnecting the pump was anything to do with it, I think taking the MV off and getting this clunking noise on the valve (or much more likely - the loose thing rattling inside the actuator) has somehow cured itself, and now, fingers crossed it seems to be working fine!

Best bet is that, by me shaking the actuator made the loose part rattling move to a different, non problematic area in the actuator, out of the way so now it works good again. Just a guess, I'm no expert, seems to be the most sensible guess though.

Thought I would let you all know, maybe someone else may have this strange problem, or one of you will in the future. Thanks very much for all your help, its been much appreciated. Im pretty hopeful it will all keep on working OK now, if not seems clear enough just to replace actuator. Thanks all once again.