My Vokera Excell 80SP's Weekend

[scatmanjohn]

Gave the Venturi a visual.

First point is you shouldn't be in there messing about really.

How can you give the venturi a "visual"

The ONLY way to get at the venturi is to remove the fan.

It will have lots of hard crusty deposits on it which will need removing. I use a small file..

this morning, the Mrs turned the hot tap on for a few seconds and after that..... the fan stopped.
I then ran the water for longer to let the boiler kick in. Following this the fan started again.

I will say it again. That is a boiler flow switch fault.

 

[rednaxela]

I'm not really messing, just looking. Being an Electronic Engineer, I'm up on electrics, but don't touch anything else.
I could see the fan blades by looking up through the burner chamber. They looked ok. The silicon pipe was in good condition with no deposits.

I think I may be missing the point on what the venturi is.. I thought it was the disc with microswitch fixed to it?
Is it something else in the flue?
If it is, I will call my man in and get him to strip it down. I don't mind taking covers off, but I'm not keen to start fiddling with the guts.

Alex.

 

[ChrisR]

what the venturi is.. I thought it was the disc with microswitch fixed to it?

Nah

It's in the fan, which is a bit involved to get out. Get yer man to do that and service it, and check the flow switch operation.

 

[scatmanjohn]

alex wrote:

I thought it was the disc with microswitch fixed to it?

Thats the air pressure switch, the tubes connect the APS to the Venturi.


Good Luck

 

[rednaxela]

Hi All.

Its time to call my Corgi man in.
From all comments here, I think I will ask him to replace the DHW Heat Exchanger. I would prefer a new one over a cleaned one especially as I have read that they do not last for ever.

With regard to the fan, it stopped again this morning when the "Mrs" briefly turned on the tap for a few seconds. (the same time as the last time it stopped, after no use all night)
While it was stopped, i measured the voltage across the slow resisitor. It was 0V.
I could see that the arm was at the correct point, ie, the flow microswitch was de-activated. I tapped the switch body, with no result. I then clicked it on and off quickly. The pump came to life for a as long as it was clicked, after a very short pause, I heard a click from the PCB box and the fan started.
My assumtions are that it could be a sticky relay on the PCB.
I believe this cannot be got as as I was told the PCB was not built to be taken apart for repair.

Hopefully, soon we will have constant hot water 8o)

Alex.

 

[scatmanjohn]

alex wrote:

I could see that the arm was at the correct point

The fulcrum arm has nothing to do with the boiler flow switch.

VENTURI.....VENTURI.....VENTURI.....VENTURI

 

[DP]

This post is going nowhere.

Despite the regulars giving good advice. advice seaker is not taking any advice.

Shame, throwing good money down the drain.

 

[Agile]

As an electronics engineer I am sure that you could replace the relay on the PCB .

There are even a few firms who "recondition" them!

However a CORGI engineer is not permitted to use refurbished PCbs as they are not "manufacturer approved".

As a DIYer, providing that you are competent then you could change the fan relay on your own boiler at home!

Tony

 

[geoff@cetltd]

There are even a few firms who "recondition" them!

Really ?

However a CORGI engineer is not permitted to use refurbished PCbs as they are not "manufacturer approved".

Really ?

Tony

 

[rednaxela]

Hi all,

ok, message received and point taken. I will ask my corgi man to look at the venturi first. He doesn't want to, but then again the advice on this site is not oriented towards cash at the end of the day.

Looking at the manual, it looks like just a case of taking the burner front plate off, removing a couple of screws, then sliding the connection ring up so that the fan assembly can slide out.
It looks very straight forward and I would like to DIY.

I have recieved mixed reviews about what can and can't be done by DIY.
Is it a case of "a compitent person can do this type of work" or is it completely illigal?
Much as I feel able to carry out this sort of thing, I don't want to go too far away from what is and isn't allowed.

I do appreciate all I have been told on here and thank you all for your time. My assumptions have been based on what I learn on here and what I have been told by my repair man. Believe me, I don't want to waste any money.. 8o)

Alex.

 

[rednaxela]

Hello, here to make an apology.... (hanging head low)

After talking to a my plumber he said it would be ok for me to have a look myself, if I got stuck, he would come round.
All went well. The venturi pipes didn't have much crust on them. More could be found on the outside of the pipes which i cleaned off. the crust was made up of very tiny ball like things.
I have taken some photo's.
I cleaned the fan blades with a soft brush. Quite a bit of powder came out.

Put everything back together and currently the hot water is keeping a much better temperature than before. It is still running hot, hotter in 30 second cycles, but is not going cold again as before.

Can you tell me if the air on the outside of the venturi tubes is important?

Also, should the hot water be very stable on this boiler? I'm still wondering if the DHW HE may still be an issue. Would it be worth measuring the temperature gradient of the water over time?

thanks, Alex.

 

[scatmanjohn]

Alex... It doesn't take much in the venturi for it to cause a problem.

Did you take it out of the fan outlet (its in two pieces) and clean the internal surfaces with a small file or similar tool.

Now what about your slow fan problem? Have you observed the boiler flow switch.
If you get get your head under the boiler you will be able to see it moving in & out. (is it very slow to go back in after a demand)

 

[vokera80e]

Replace the microswitch..£6.

 

[scatmanjohn]

Replace the microswitch..£6.

What ? and then find its just the push rod not going back in?

Did you read the earlier posts?

 

[rednaxela]

I removed the fan from the upper casing, but that is as far as I went. I had access to the venturi tubes from the silicon pipe exit on the horizontal pipe, and from the opening on the vertical. I think I got it all off from inside with my small file.

With regard to the slow fan stopping. When it last happened, I was lucky enough to be able to take the main cover off. The push rod assembly had returned to its rest position leaving a gap between it and the microswitch.
Perhaps the microswitch is intermittent, or I am wondering if it is a sticky relay on the control PCB. (I'm not sure if this can be dis-assembled as it looked like the top PCB had been plastic clip welded into the casing). I would need to have a proper look though. I see this allot in my work. Many electronic circuits are not designed to be repaired. (on purpose)

I think I will leave it a few days to see if the fault happens again, just in case everything was related...

Thanks,
Alex.