Ariston Micro Genus 27 Blowing fuses

[jack7755]

Hi Folks,
I have a couple of questions that you might be able to help me with. Firstly, can someone help with a manual for the Ariston Micro Genus 27 MFFI. I have tried the MTS web site and they pointed me at www.centralheating.co.uk. When I tried there the files I downloaded were corrupt. I phoned their tech support number and they asked me to request the documents via their website. This I tried to do but the page won't let me complete despite filling in all the information requested. So can anyone help?

My second question is related to the same boiler. The boiler is about 5 years old and it has started blowing fuses. All was well until the cold snap a few days ago when we tried to boost the system for 1hr. The boiler didn't start. When I looked at it the power light was off. I checked out the system and found the two 2 amp fuses on the PCB blown. The fused spur was still ok. I have since replaced the fuses and the boiler fires up for a while and then there is a flash as the fuses blow again. I replaced the fuses again and the same happend, although the boiler fan for about 10 mins this time. I had thought that it might be the pump that is blowing the fuses, but I'm not sure. Do any of you guys have any knowledge of this fault. I have read all the posts I can find on this kind of thing, so I will go home tonight and check the pump is not jammed.
Any help would be appreciated as the weather is heading for minus 4 by Thursday.

 

[fela kuti]

i have uploaded the service manual here

http://www.megaupload.com/?d=CIFKWGF0

 

[jack7755]

Thanks for the link to the manual it is just what I need. I am just hoping that someone can help with the diagnosis.

 

[ollski]

What resistance readings are you getting across the pump and the fan?

 

[jack7755]

Hi thanks for taking up the challeng. I have metered the fan and get a reading of approx. 30 ohms. The pump has a capacitor across it as I am sure you know and I get a low initial reading but it settles on about 215 ohms. Does this provide any clues? I'm not sure what the norm is for these devices. I have made my measurements at the connector end, unplugged from the PCB. Thanks again..

 

[jack7755]

A bit of further information. On further checking there doesn't appear to be an earth fault on the fan or the pump. Tonight I replaced the fuses and switched off the CH and powered up the boiler. I drew hot water from the kitchen sink on and off for about 45 mins and the system worked fine. I then brought on the CH and the system worked fine, bringing the radiators up to temperature. I continued to draw hot water from the kitchen sink and all remained fine. The boiler turned off when the temperature was reached and came back on when needed. This went on for about 1 and half hours, when the outside temperature was just below freezing. At the end of the hour and a half the fuses went again. Could this be down to sludge in the system. The combi boiler was installed on existing radiators and pipe work and I wasn't around to check they flushed the system. Any help would be gratefully received.

 

[jack7755]

Hi folks,

I know you are doing this in your spare time but is there anyway someone could look at this post.

Regards

 

[Gasguru]

If I were faced with this scenario I would stick the PAT (Portable Appliance Tester) on the fan and pump. This would test (at high voltage) if the windings are breaking down. A normal multimeter can't do this.
The gas valve safety solenoids also run as mains voltage.

I'm not sure what voltage the diverter actuator runs at but it may be worth unclipping this and checking as water leaks are possible around the diverter operating pin.

Have you checked the board(s) for brokem joints - repeating surges of current may blow a fuse.

 

[jack7755]

Thanks for that input, I hope to get a hold of a PAT on Monday. In the interim has anyone had a similar problem to mine and maybe shed a bit more light on the problem. I will take the covers off the system today and use the mark one eyeball to check out for leaks.

Thanks again, in anticipation.

 

[jack7755]

Eureka!! I think I have found the problem. When I took the cover plates off I saw some staining near the cable entry point inside the boiler. On further examination I followed the likely route and there was a lot of staining on the pipe up to the heat exchanger. There was a bit of a puddle on the flat surface that the pipe goes through. I then removed the plug from the diverter valve actuator and it was dripping wet. Along with this was the unmistakeable smell of burning from the top half of the actuator. My next step is to cure the leak and it looks like changing the actuator would be a wise precaution. Can the actuator be removed and replaced without draining the boiler? The manual says unplug the electrical connector and remove retaining clip "S1". Is this a wet connection or does the actuator operate on a sealed valve inside the brass body.

Regards

 

[Gasguru]

Remove clip and pull out the diverter head. You need to sort the leak though.

 

[jack7755]

Thanks for that, but can you tell me if I need to drain the boiler before disconnecting the diverter valve? I will be taking care of the leak, what is the best compound to seal the threads? I should have the new valve by Wednesday. I will give it a go then.

Regards

 

[Gasguru]

The actuator head is removed by removing the retaining clip. You do not need to drain the boiler to do this. Just replace the head.

I don't understand where the water leak is.

Are you saying the water leak is from the combustion chamber? There are only two connections onto the heat exchanger and I've not known them to leak.

If it is from the diverter pin in the left hand manifold then you will need to drain the boiler (heating and domestic side). Uses standard fibre washers underneath. You will need a set of O rings as the plate heat exchanger has to be removed (from memory so I may be wrong). You can probably buy a repair kit but I would advise you replace the whole diverter section.

 

[jack7755]

Thanks again, the leak seems coming from a pipe joint. The location of the joint is, if you have the manual, page 6 figure 1.18 the joint is marked "J" in the picture. There was staining down the pipe with a collection of water on the self as the pipe passes down to the lower section of the boiler. I can't see any other leaks, but once I have the new part in, I will keep an eye on the various possible leak points before I re-assemble the boiler cover plates.

Regards

 

[Gasguru]

Probably a 3/4 fibre washer.