Viessmann 100 Combi WB1A flue melted

[suntanneddude69]

Hi,

Have any other engineers come across or heard of the flue connection on top of the boiler casing melting (and not by using a blowtorch for any comedians ) for this early model of boiler?

SD

 

[JohnD]

have you seen it happen then?

got a photo?

 

[mysteryman]

It is caused by the boiler overheating, quite possibly due to a failed pump or other circulation issue, or sludge.

 

[JohnD]

wot no thermostat?

 

[mysteryman]

There is a limit thermostat, obviously. The OP asked what the likely cause was, and I have given the answer to that question.

 

[suntanneddude69]

sorry no pics.

history: called out to F4 fault -ignition problems, changed to new black spark generator with new PCB & ignition electrode. this cleared F4 but then thing was overheating rapidly, checked black flexi's from HE and all crispy for a sealed system? looked at Hep2o pipework & original installer has put standard & not barrier pipe in. Concluded crap in system so opened up flexi and nice + crispy with lots of debris. Opened up CC (yes I know different circuit etc) and insulation ring had seriously crumbled, spoke to Viessmann tech support who agreed with me that burner assembly ought to be changed for safety reasons as difficult to clean as will leave hot spots & lead to vitiation etc. They said it had happened over a very long time by condensate water getting onto this. Changed, powerflushed etc. Advised idiot customer about ****e installation and also very long horizontal condensate run in unheated & very cold loft in overflow pipe. Any way spoke to very senior service engineer from V and he said condensate had probably frozen & due to pipe length boiler had not 'realised this' and got too hot & melted flue. Customer changed condensate pipe himself but now thinks its all my fault & we have been fleecing him for parts not needed. But a boiler is a sequence of events and you cross each one as you get to them, correct? Any ideas short of capping his meter for him (FOC of course )

 

[suntanneddude69]

it cuts out at about 88 degrees but gets to this point in seconds, have checked & water in HE.

 

[Agile]

I would love to become more involved in this discussion but it should be in the CC !

Can the OP repost it there? Or a helpful mod?

Tony

 

[suntanneddude69]

PostPosted: Fri Jan 14, 2011 12:20 am Post Subject:
I would love to become more involved in this discussion but it should be in the CC !

Can the OP repost it there? Or a helpful mod?

Tony

Have applied for access to CC

 

[mysteryman]

Which bit of 'poor circulation' don't you understand?

 

[suntanneddude69]

mystery man,

I do know full well what poor circulation is, thank you, but after speaking to tech support and them confirming my thoughts, this boiler has more than one problem. Standard pipe has been installed which is sucking in air, causing debris in system - issue 1. condensate pipe too small & long horizontal run which has obviously frozen causing insulation ring to crumble thru backing up - issue 2. flow switch sticking - issue 3. intermittant f4 faults - issue 4. flue inner (plastic) pipe melted - issue 5. And the list goes on.

So 'poor circulation' is NOT the only issue.

SD

 

[suntanneddude69]

To the person who has sent me a message,

Your settings will not allow me to answer you as I am not showing as your friend

SD

 

[Agile]

Its the prospective friend who has to apply to be a friend first!

It does not always work though! I wanted to be a friend to Beyonce but she ignored me! So did Susan Boyle and then even Ann Widdicombe!

 

[mysteryman]

I fully understand that you have had other problems. However, the question you asked was about the cause of the flue melting, and you have told us that there is much debris in the system, and what you describe as flowswitch sticking. This is a further indication of dirt.

These flowswitches rarely give false indications. Condensate pipe problems and F4 problems are not the cause of the flue melting.

If there is no circulation when the burner fires, the temperature rise can be so rapid that the flue melts before the limit thermostat trips out.

Regardless of that, you need to get the system clean before it will work. The boiler was clean internally when it was installed, and it doesn't make itself dirty.

In general, properly installed boilers do not give trouble.