Replacing Grundfos 15-60 selectric pump

[donkeeboy]

Hi,

My worcester bosch boiler CDI 40 (not combi) keeps going on a E9 fault code every week or two - I reset the boiler and everything works fine until the next time. E9 means 'Safety temperature circuit has tripped'. Been like this for 2 or 3 months now.

I phoned worcester bosch, he said take the bleed nut out the pump (Grundfos 15-60 selectric - on speed setting 3), force a screw driver in the hole and see if I can stop it - if I can then I have a weak pump. Well I did that, and I could stop the pump with screw driver pretty easy. So it looks like I need a new pump.

Firstly - is it a forgone conclusion that the pump is dying? Is it worth me taking the pump out and cleaning it in a situation like this?

Secondly - Grundfos have a good name - but this pump is only 3 years old. Surely I should expect it to last longer than that. Whats the typical lifetime of a 15-60 pump? It was all installed with my new boiler by a corgi guy 3 years ago.

Thirdly - I'm looking at the replacement bare pump, I can pull this off myself, however all the product pages state the pumps are OK for systems up to 35KW. Well my boiler is 40.8 KW. Maybe this is why it only lasted 3 years, is this a problem? I cant see no bigger pumps, should I get another 15-60 or something else do you think? My system is big - 19 rads + normal style hotwater cylinder. Its a sealed system.

Thanks in advance everybody.

 

[AllyBongo]

If all your rads are heating ok, its probably not your pump

 

[donkeeboy]

Thanks for the reply.

What about this test that Worcester bosch told be to do - by pushing a screw driver into pump hand and see if it will stop? I did that and stopped it - they reckon that means I got a weak pump. Anyone got an opinion on that?

When I get the E9 fault code, nothing works, boiler shuts off. Once reset it will indeed work and get rads hot for a few days, or may a couple of weeks before the next E9 fault.

Its either a blockage, the pump, or the boiler sensors or something. I really dont thnks its a blockage, else prob would stil be there after boiler reset. Only drained the system a few months ago, water was pretty clear.

I have actually witnessed the boiler do this by chance one time when I was stood next to it - it starts making a lot of noise - like it was overheating. Sounds likes its taking off. So I dont thinks its boiler sensors tripping out by mistake - there really is something happening to it. Im no expert, but I think it prob well could be the pump.

I dont want to get a new one tho if I really dont need one, or its gonna die after 3 years again though like this one.

Thanks

 

[cdodds2004]

many things can lower the life off your pump, for instance if its a old system and is pumping aload of crap around that can lower life exspectency of the system drastically, do u no if the system was power flushed before the boiler was installed? does it have inhibitor in? usually a sign of a a well maintained system,

 

[donkeeboy]

Yes it was all 3 years ago - new boiler + pump. Yes it was all power flushed at that time. Its had inhibitor in it, and I drained it a few months ago water still pretty clear. I put new inhibitor in it then too. Its all pretty new and in good nick in other words.

I just wonder about the adverts for the Grundfos 15-60 pump - saying for use on systems up to 35KW. Mine is 40.8KW.

 

[AllyBongo]

What temp does the boiler get to when it starts boiling? Could be the primary sensor playing up, think cdi's should shut off about 88 degrees. Check the burner light to see when it goes off.

 

[donkeeboy]

Under normal operation, it never gets hotter that 80/81 degrees. When it saw it go crazy that time, it went into the 90's and was going up VERY fast. I turned it off in the hi 90's quick.

Basically it seems to act very much like it is air locked - but I am SURE it is not an airlock, I have been bleeding the pump for air a 100 times since this started happinging and no air - well only small amounts of air. It was airlocked after I drained it in the summer, and that time you could really hear loads of air spurting out, not like now.

Cheers.

 

[cdodds2004]

how many radiators do u have on your system, i would hedge my bets and say that your pump is fine on that system, so u have ruled out dirty system, and air, could be a bad pump or possibly a faulty temp sensor causing intermitent cut out, also dont rule out faulty circuit board but would explore all other avenues first, first port of call would be to replace pump, rule that out first, maybe try the new modulating pumps

 

[tamz]

It sounds like there may still be a pocket of air in the system which gets trapped in the boiler from time to time.

You can stop any pump with a screwdriver and it does not take much to hold it.
The 35kw you mention is a bit of a generalisation. Pumps should be selected to suit the load which can be calculated.

 

[donkeeboy]

Thats interesting what you say about being able to stop any pump like that. Now im not sure what to think, im thinking more towards a fault in the boiler now, but thats just a guess.

By the way its just done it again (E9) 30 mins ago. This time I removed the bleed screw from pump completely, reset the boiler, waited 20 mins while it did its initialisation tests, and watched it. When it fired up 20 mins later, there was NO air emitted from the pump (bleed screw completely removed). I was thinking this may be a good idea as the airilock (if that what it is) should be right there, in the boiler directly before the pump at that point in time.

Interestingly, when i found the boiler in its E9 state just a while ago, I noticed the pump was still running. I took off the bleed screw then too, no gush of air, and pump was definitely spinning, I poker a screw driver in there.

This is starting to happen ever more frequently now. Im more confused now tamz has contradicting what Worcester Bosch told be about the pump (ie being able to stop it with a screw driver means its no good).

Any tips on removing an airlock? Previously I just been loosening it off and often it fizzes a bit buit nothing much then stops, I tighten it back up. Should I take off the bleed nut totally, and leave it running like that for an hour or two or something? I want to try and find the airlock, or to be able to rule it out.

Cheers guys.

 

[tamz]

Before you can tell the difference between a weak pump and one which is ok you have to have felt the difference between both. If it is really easy to stop it it may indeed be the pump in which case swap the head for a replacement 15 - 60.
In any case the problem is caused by circulation or lack of it including air.

Just a thought. Is the pump wired to the boiler?

 

[cdodds2004]

u thinking no pump over run wired in, i have seen a few boilers wired up like that naughty naughty

 

[donkeeboy]

Sry gents, i missed last 2 msgs as they was on the next page! Didnt realise...

About the pump, no I have not felt the difference between a weak pump and a good one I am afraid. I can just say I can stop it pretty easy, but it does requie an amount of effort. For instance, apart from the pain, I would NOT be able to stop it with my finger for instance, its still got mopre force than that.

Yes the pump is wired into the boiler. It should all be correct and proper (and modern) it was all put in 3 yrs ago new system by professional corgi guy, and wired by professional electrician.

Cdodds, if 'pump over run' means the pump running for a few minutes after boiler fires off, then yes it does do that.

Gonna carry on bleeding it as much as possible, if it carries on E9 faulting, and I think it will, then I will replace the pump. Thanks guys.

 

[spaarks]

Your pump should last a lot longer. I installed my SMC Commodore 130 over 20 years ago and it is still pumping well and very quiet.

 

[tamz]

I installed my SMC Commodore 130 over 20 years ago and it is still pumping well and very quiet.

One of the best pumps ever made.

 

[donkeeboy]

UPDATE:

Just a kwik recap - this is not so much a problem with replacing a pump - my Worc-Bosch boiler keeps tripping out on E9 (temperature rising to fast trip out). I was lead to beleive by WorcsBosch it would be the pump, now I'm no expert but I really do not think it is the pump, it works fine between trip outs, and is only 3 years old. Therefore I have been a bit stuck, not wanting to replace part after part hoping to eventually replace the right thing.

Well anyway, I am now able to recreate the circumstances to get this intermittent fault to occur! I am very much hoping it will mean something to someone, and get me a better idea of how to pregress forward from here. OK, this is how to get the fault to happen :-

A) The central heating is ON by itself (I got a 3 port MV btw)
B) Then whilst the CH is still ON, the HW kicks in too, so now CH+HW are both ON.
C) Now whilst CH+HW both on, room temperature is reached, and CH turns OFF, so now just HW is ON.
D) Soon as C happens ((a few seconds later), the boiler takes off, starts getting really noisy, temp starts rising too fast. The fault is reproduced! E9 trip out!

I should point out that the motorised valve is moving from position to position perfectly fine, I can see it moving, and CH and HW work fine independantly, and indeed both together, except when the CH goes off whilst both CH+HW are on at the time.

What can it be? I am really very keen indeed to get this sorted now, and help will be very much appreciated indeed. Thanks in advance.

 

[Spanner2k7]

hi,
if your heating is working fine, on its own and when hot water is on, then i would suggest there is nothing wrong with the boiler or pump, if the boiler locks out when it is just hot water then this is pointing to a restriction between the motorised valve hot water side back to the boiler. Is there a manual air vent my the cylinder, if so open it to check for air. If there is no air then I would say some kind of blockage on the pipework

 

[stevetheplumber]

since both work fine indpedant or together its not boiler since it happens when the valve moves id try another 3 way valve posible the ball in the valve is loose or its sticking although i belive there is always flow thru a 3 way regardless of position another possibity is the power to pump is going of during the valve travel due to a sticking micro swith in the valve wire a test lamp to the pump supplies and see if it goes out when you recreate the fault
unlikly to be a blockage as they work at other times

 

[spaarks]

The odd thing is that the HW works ok on its own, and that the valve moves to the correct position in condition 'C'.

How about checking that the pump is still running when 'C' happens? I can't imagine why it wouldn't but it seems like something is stopping the flow to the HW coil and you seem to have eliminated the valve and the pipework.

 

[donkeeboy]

Thanks gents.

No manual vent on cylinder that I know of,. I have been bleeding the pump like crazy though (HW only 2m away) no air of any significance.

Yes the pump definitely keeps running when it trips out (stage C). It keeps running until reset.

Its all pointing towards MV, or a blockage. Neither really make any sense though. Im sure its not blocked I just drained it summer, water was very clear. MV works, all the kit is 3 yrs old. Def not pump nopr boiler though so glad I didnt replace pump.

I think I will drain it again next mild day we get.

One more thing - is it possible for MVs to get 'out of alignment' so to speak? IE moving to positions but being a bit out of whack causing something like this?

Also, if I drain the system again, should I have MV in a specific position? I guess CH+HW makes sense, but in summer I left it alone so it would have been in CH-OFF HW-OFF position. maybe that means any debris will drain into the HW loop i dont know.

Strange how it all works though most of the time, and all of the time on CH, and indeed HW. It just needs that specific sequence of things to happen to do it, and even then not always.

Its happening more and more freqently, started out once every two weeks or so, then every week, every few days, now 10 weeks on its just happened 5 times this weekend alone.

Hmm very strange. I will keep you updated as things pan out. THanks for your help everybody.

 

[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