Ravenheat HE85T combi boiler CH constant re-firing

[psarinuk]

I was not at home when he serviced the boiler and wife is not sure if he opened the combustion chamber.

I've looked at some other threads on similar issue, they are pointing towards faulty fan PCB.

Is it worth getting a new one and replacing it (£50)?

 

[Agile]

I never think its worth getting any replacement part until I have diagnosed the actual fault !

However, as I pointed out on the 10th Novemberm it could be the fan PCB and its would not be a bad idea to replace it as it is quite probably the fault!

Tony

 

[Slugbabydotcom]

With 13 screws this has the most idiot proof combustion chamber cover that I have come across.
The flue sensing ring should be at 90º to the direction of the fue elbow. Experience has taught me to try it in different positions as the exhaust flue pipe is not always central in the flue elbow.
I can't see the boiler but from the info so far I concur with Tony regarding the fan pcb being the most likely culprit.
Don't forget there are other candidates and you can add a flame sensing problem to the stuff I wrote previously

 

[Agile]

I always imagined that it should be at 180° to the outlet.

Do you rotate it whilst monitoring the pressure applied to the APS ?

Tony

 

[Slugbabydotcom]

Its impossible to freely rotate it as the screws for the flue elbow go through it. There are only 4 positions it can be in relation to the flue bend.

At 180º; there is reduced airflow as it has further to travel So I would assume that:-
At 90º; the vacuum is nearest to the average of the rest of the flue.

 

[psarinuk]

Thanks Tony and slugbaby!

I spoke to Ravenheat as well and they informed that too much fan PCBs on these are failing these days, so they advised me to replace that.

I rang them twice so I could speak to a different adviser and he said the same thing, so much so that the price for Ravenheat fan PCB has doubled from £25 to £50 in retail due to demand he said!

Have to buy from some online boiler spare company as Ravenheat don't stock spares!

As alawys, I would keep you posted with the outcome when I replace one.

 

[Agile]

I dont know why you think you will get better information from Ravenheat! We actually repair boilers, they just answer phones and trot out the company policy stock answers.

Ravenheat have their own company to the right of their HQ which sells their spares! But they are also sold by all the other boiler parts suppliers.

Tony

 

[psarinuk]

Hi

Probably bit too early to celeberate but replaced the fan PCB today and the CH quick cycle when boiler is COLD has not happened since fan PCB replacement.

Maybe the boiler is not cold enough to produce the same situation yet, would know for sure tomorrow morning or in a few days.

Tony, Slugbaby: I did not touch the flue ring sensor or check its alignment with the flue elbow. It was working before, so I hope its not something I've to worry about now.

Also cleaned the iron oxides in magnaclean, there was not much ferrous material inside and the water was crystal clear (maybe due to the inhibitor).

Comments welcome and thanks once again for your help!

 

[Agile]

I think this may be a faulty fan relay PCB !

Tony

Better late than never!

I have never changed one yet and I am interested to examine why they fail. Is there any possibility that you could post the old one to me. NW10 address easily searched on Google.

Tony

 

[turbofan]

was it a suscess story or not,let us know,please.

 

[psarinuk]

So far so good..

It seems the problem is sorted as the cycling has not happened since, but please allow a few more days, it has gone fine before as well for more than a week and then it all went wrong..

So I will give it a few more days before awarding medals..

I've just checked my inbox and a few people have asked for the old part. I don't think it will help people other than ones like Tony who can investigate why it failed.

Tony, please PM me your address.

Thanks.

 

[bluemore]

Hi all

I've a Ravenheat HE85T combi boiler which is also similar to CSI85.

WHen I put it ON for CH, the boiler comes on and then goes off. It carries on this cycle every 5-10 seconds, so I've turned it into DHW mode only (CH off).

DHW is running absolutely fine.

WHat could be the issue? I replaced both DHW and CH thermistors in Jan 08 when I had an intermittent DHW issue.
(The CH thermistor is a dry clip on type, the part number is 0007son11010/0 and more expensive than the DHW one which is a wet type with part number 0007TER05005/0)

Thanks in advance....

I've just started my annual battle with my csi85 but by now I know what goes and what the signs are.
The fans are crap but that is also contributed to by condensation in the chamber due to poor fittings. This creates rust on the spindle so plenty of light oil...
The thermistors are really poor quality and give a wide range of readings depending upon the moon phase. I used to read mine using a meter and a cup of hot water (with the sensor suspended into the water with a bit of string. Now I just replace them (CH and DHW together) when I get the usual symptoms as described.
I have had on at least 3 separate occasions, water collect inside the ring (with the pressure tube for balancing air). This causes the boiler RED light to come on. It must be the wind direction. Easy fixed with kitchen roll.
So beware of people telling you it's PCB's or gas regulators and the like.
I have found a simple but effective test for the thermistors. The connections (green female connector) when wiggled will cause the boiler to ignite on and off. I use this as a sure sign they need replaced.
I regard the thermistors as (at least) and annual replacement part. Its is the weakest design of the boiler