Biasi 24S ...Pump problem?

[Tunni56]

Boiler stopped working over the weekend. Green status light rapidly flashing (not locked out)

The first fault listed in the service manual is the pump and the problem appears to be here. On inspection, I noticed a very slight leak under the pump housing where it mates with the boiler. Also water pours out in a non stop if the brass bolt is removed (that's not right is it? ...I expected possibly a drop or two but not continuous leak/flow)

On removing the pump and easing out the impeller, it appears that water has found it's way inside the actual pump ...This definitely can't be right!!

My best guess is that the rubber seals have failed allowing the water inside the pump, after I dried everything out the pump works ok (on the bench) but on refitting and tightening the 4 bolts up , the problem persists and I'm back to square one.

Can anyone confirm my suspiscions ie that water is entering the pump housing due to the rubber not sealing properly? ..or is there another likely explanation.

 

[hi-spec plumbing heating]

ya change it

 

[Agile]

Is this the original pump with the serial number on the body?

Is the shaft free to turn ?

Its normal for about 1 li/min to come out of the screw.

Is the large rubber washer correctly seated?

When fitted obviously the impeller must be free!

Tony

 

[Tunni56]

Hmmm. You got me guessing now Tony. especially if it's normal for 1 litre/min to flow out the vent screw, probably not the pump after all and I need to look elsewhere? In fact the pump does look fine, the resistance on the windings is spot on spec and impeller rotates free.

I assume the service manual lists the faults in logical order? If so second on the list after the pump is the 'full sequence board' Other than replace and see if it works, is there anyway of checking the board out for faults?

Any other ideas?

Phil

 

[ChrisR]

Does the pump coming on operate its flow switch? You'll need a small mirror iirc!

 

[Tunni56]

Going to have another look over the boiler see if I can isolate the fault. I notice that 6 resistors on the ignition device have got so hot they have scorched the board. I've seen it on pottertons (and no doubt it's prevelent on others as well)

This type of thing is just poor design, an engineer at potterton once told me they knew full well that one of their designs caused premature failure and that they did get around to a mod. Not much use when you have to fork out for a new board due to failure. Built in obsolescence. Who here doesn't believe they could easily design a boiler that would last 20 years or more

Phil

 

[Agile]

Those resisistors discolour the varnish but thats normal.

The first thing is to see if the pump operates the system flow switch.
You have to do that within four seconds otherwise the pump is turned off.

Tony

 

[namsag]

Biasi is the low end of the market boiler and you will find that most of the good installers won`t touch them unless the customer specifies them and repairs are left to people who struggle to get there own work and have to take the crumbs from manufacturers.

But if the pump is a wilo which basically was the same as a euramo.. Then when you take the centre screw out and water sprays out then the pump is shot

 

[Agile]

Any brand new Wilo lets a lot of water pass!

Thats normal for that make.

Tony

 

[namsag]

Will disagree with you there Agile although they let more out than a grunfoss they don`t let lots out and certainly not enough to soak you or spray at you.When working correctly
Only couple of days ago half a dozen of us where discussing wilo pumps and everyone agreed when they are knackered they spray at you when screw undone.
Not a bad pump better than myson and at 46 quid for 2 excellent value

 

[Agile]

I see a lot of virtually new Wilos and they all let a lot of water out.

They have plastic bearings which are very quickly worn by fine dirt in the system but they virtually never fail electrically.

In contrast I find that Grunfoss with a very hard shaft and a ceramic bearing are much more resistant to fine dirt but they often fail electrically with a very characteristic smell which I teach to my trainees.

After normalisation, I replace about 20-30 times more Grunfoss pumps which have failed electrically compared with Wilos.

The Wilos have recently been redesigned and can no longer have just the head changed!

Tony

 

[Tunni56]

I'm still trying to work out if this is a knackered pump causing the boiler not to work.

The water coming from out the screw vent sounds as if it's within spec ie it's a steady trickle/flow ie it doesnt spurt.

The large rubber washer along with the smaller rubber seal associated with the pump/impeller seem to be in good condition BUT after carefully refitting the pump and making certain that it is properly tightened the pump still drips water from the bottom of it's housing.

Although the shaft is free to turn/impeller free the pump does not operate when the boiler is turned on. The only action from the boiler is a few clicks and whirrs from the actuator on the divertor valve before the green LED clicks and starts ins rapid flashing.

Tony, namsag, does it sound like a faulty pump (it's the original Wilo) and are they as cheap as someone mentioned (£46 for 2!!) If so I'll just get a new one. At least that way I can eliminate it from my list.

Thanks for the answers so far guys

 

[Agile]

It sounds as if your pump is NOT working!

But you can test it by applying mains from a seperate source.

If that makes it work look at the positioning of the male and female pins in the plug/socket.

Theres a big chance that you will NOT be able to just buy a pump and it will fit! There are about three different ones fitted to the boilers and there are two different pumps being sold as general pumps.

Tony

 

[Tunni56]

My original suspiscions about the pump might still prove to be right. Although I got it to work on the bench with a seperate power supply it did not work when re attached to the boiler. I think this is to do with water entering the pumps main housing (hence the drip)

Can anyone confirm that the likely ingress of water into the pump housing is as a result of wear and nothing to do with the two rubber seals (as these seem to be OK! Or could seals that appear OK be faulty.

I cant understand how water can enter the main pump housing, is there another route the water can take apart from through the front past the large rubber washer?

...And how much are the pumps to buy (Wilo NFSL/premium -1C)

 

[Tunni56]

Forgot to add that the pump does not start even when separate power supply connected to it