# Viessmann: What the hell is this?



## futz

Viessmann Vitodens 100 maybe two years old. It locked out with a F2 fault (high limit) once. I reset it and left it. I was horribly overloaded with work at the time. Had no time to do much more, and I thought, "It's too young for anything very major."

Now maybe six months later it F2 faulted again. I opened it up and found this mess. Vacuumed it all out.

Don't know whether it's related or not, but the fan is quite whiny and loud. Pulled it and had a look. No obvious problems - just the sound.

From the disintegration of the bottom of the rear refractory I'd say it's had some excess water in it. The condensate trap didn't _look_ horribly plugged, but may have been. It's hard to tell by looking and I had already cleaned it out when it occurred to me that I should have poured some water in it and checked before cleaning. It was at least dark brown at the bottom.


----------



## dclark

Multiple issues, methinks…
F2 suggests circulation issues, air, pumping issues on the water side.

Any possibility of cross contamination at the vent termination?
Rebreathing the flue products through the boiler can lead to some pretty odd looking deposits.
Combustion air from inside can as well.

The air/fuel damper (flapper) could be sticking. There may be an upgrade kit available. The upgrade has a little bump on it to stop it from sticking closed.

Vent lengths less than the minimum (especially if you have only run one pipe) can make the inducer noisier as well.

I’d send those picks to the guys in Langley. If you get to the right guy there, you’ll find good help available. I usually call them before I try the 1-800 number.


----------



## Wilton Don

Is it in a room were any chemicals are stored ?


----------



## Catlin987987

I have seen NTI and Munchkin boilers do that. Never that much though, usually only a few teaspoons full.


----------



## vinpadalino

Wow that's a lot of soot for a 2 year old unit. 
I would check gas pressure


----------



## Catlin987987

vinpadalino said:


> Wow that's a lot of soot for a 2 year old unit.
> I would check gas pressure


And a combustion analysts.


----------



## Protech

Is that soot or rust? Looks kinda like rust. I've seen boilers do that from restricted exhaust or clogged condensate.


----------



## wyrickmech

To low on water temp will cause excess condensate which will cause rust.


----------



## Catlin987987

wyrickmech said:


> To low on water temp will cause excess condensate which will cause rust.


That's a condensing boiler, the point of it is to run it a cool as possible.


----------



## wyrickmech

Catlin987987 said:


> That's a condensing boiler, the point of it is to run it a cool as possible.


below 140 causes problems that's why there is rust.


----------



## Catlin987987

wyrickmech said:


> below 140 causes problems that's why there is rust.


How do you figure that?


----------



## Coolcanuck

Love me a good maintenance contract. We just pulled out a 7yr old tankless that was never touched. The unit was a right off. What customers are "saving on energy" they should be spending on contractor maintenance.


----------



## wyrickmech

Catlin987987 said:


> How do you figure that?


the surface of the heat exchanger will stay wet from the sweat effect of the cooler water it also causes the acidity to increase inside and out. That is what is causing the excessive rust. You go above 140 and the thermal effect changes to a dryer exchanger. The exhaust will carry the moisture out at the higher temps but when you drop below 140 there is enough difference between the burn chamber temp and heat exchanger temp it allows the moisture to condense with some of the gases in the chamber witch makes it acidic.


----------



## Coolcanuck

wyrickmech said:


> the surface of the heat exchanger will stay wet from the sweat effect of the cooler water it also causes the acidity to increase inside and out. That is what is causing the excessive rust. You go above 140 and the thermal effect changes to a dryer exchanger. The exhaust will carry the moisture out at the higher temps but when you drop below 140 there is enough difference between the burn chamber temp and heat exchanger temp it allows the moisture to condense with some of the gases in the chamber witch makes it acidic.


So what you are saying is condensing units are bad. Gone are the days of 180-160. That's why they make the stainless steel lingers around the copper tube. Back to maintenance, doesn't take long to plug them up, use them old blockbuster cards lol


----------



## Catlin987987

wyrickmech said:


> the surface of the heat exchanger will stay wet from the sweat effect of the cooler water it also causes the acidity to increase inside and out. That is what is causing the excessive rust. You go above 140 and the thermal effect changes to a dryer exchanger. The exhaust will carry the moisture out at the higher temps but when you drop below 140 there is enough difference between the burn chamber temp and heat exchanger temp it allows the moisture to condense with some of the gases in the chamber witch makes it acidic.


On a regular atmospheric boiler I agree, on a conserving boiler I do not. There same with materials that resist the effects of condensate for a reason. Long gone are the days of min 140 return water temperature.


----------



## Catlin987987

Coolcanuck said:


> Love me a good maintenance contract. We just pulled out a 7yr old tankless that was never touched. The unit was a right off. What customers are "saving on energy" they should be spending on contractor maintenance.


I bet that tankless unit was pulled out not to bad combustion but the water side of the heat exchanger plugged with build-up.


----------



## Coolcanuck

Catlin987987 said:


> I bet that tankless unit was pulled out not to bad combustion but the water side of the heat exchanger plugged with build-up.


The heat exchanger was pretty bad, sensor and igniter fell apart which was initial call (someone else went, I replaced afterwards). Rinnai unit. There was a leak on a part, not sure which one and another issue. J-man figured it would be cheaper to replace then revive. Up here we have a lot of people not doing maintenance on equipment. I don't have a hard time showing customers what needs to be done and doing it though. They just don't get told what's required by installers/builders.


----------



## Catlin987987

Coolcanuck said:


> The heat exchanger was pretty bad, sensor and igniter fell apart which was initial call (someone else went, I replaced afterwards). Rinnai unit. There was a leak on a part, not sure which one and another issue. J-man figured it would be cheaper to replace then revive. Up here we have a lot of people not doing maintenance on equipment. I don't have a hard time showing customers what needs to be done and doing it though. They just don't get told what's required by installers/builders.


The opposite is here. People think they never serviced there old hwt so they shouldn't service there tankless or combi-heater.


----------



## Coolcanuck

Catlin987987 said:


> The opposite is here. People think they never serviced there old hwt so they shouldn't service there tankless or combi-heater.


Company I'm with now is big on maintenance and service agreement customers (lots of furnace and a/c) offering discounts and priority service. Makes for easier sales. Keeps a service guy busy year round as well. This is my first spring, for a few years, working full hours and we're booking july up already. If you're going to clean the duct work why wouldn't you clean the pipes haha I'm also kinda missing my spring break after the winter rush


----------



## Harryparatestes

F2 fault as dclark indicated is high limit. Most likely your boiler was exhibiting an *F4* fault: No flame signal.
*Futz:* Take a service and maintenance course over at Viessmann - They're right in your back yard and the course is free. You have no excuse not to. You could have at least called your Viessmann rep and asked about this.
The same goes for *wyrickmeck:* Do you really think any major boiler manufacturer - especially Viessmann - would produce a condensing boiler that is prone to rust from condensate?? I think not.
dclark catlin987987 and others are trying to point you in the right direction: Service the boiler on a regular basis and use proper diagnostic tools when you do, including a manometer, flue gas analyser, *AND* the service manual. Oh yeah, and a phone so you can call the manufacturer if you run into a roadblock.
So what is that stuff in the combustion chamber? Take the course.


----------



## rjbphd

Harryparatestes said:


> F2 fault as dclark indicated is high limit. Most likely your boiler was exhibiting an F4 fault: No flame signal.
> Futz: Take a service and maintenance course over at Viessmann - They're right in your back yard and the course is free. You have no excuse not to. You could have at least called your Viessmann rep and asked about this.
> The same goes for wyrickmeck: Do you really think any major boiler manufacturer - especially Viessmann - would produce a condensing boiler that is prone to rust from condensate?? I think not.
> dclark catlin987987 and others are trying to point you in the right direction: Service the boiler on a regular basis and use proper diagnostic tools when you do, including a manometer, flue gas analyser, AND the service manual. Oh yeah, and a phone so you can call the manufacturer if you run into a roadblock.
> So what is that stuff in the combustion chamber? Take the course.


Who the hell are you to say this withoute intro??


----------



## plumberkc

I don't know but I got a laugh out of his username.


----------



## Phat Cat

plumberkc said:


> I don't know but I got a laugh out of his username.


Ditto - Would not have noticed until you mentioned it. Thanks a lot, now I have visual in my mind and it's not pretty. Lol


----------



## Tommy plumber

Phat Cat said:


> Ditto - Would not have noticed until you mentioned it. Thanks a lot, now I have visual in my mind and it's not pretty. Lol












Well who on earth is going to shave his.......well, on second thought, nevermind. I withdraw the question.....there are some questions that I don't want answered.


----------



## CTs2p2

Is it converted to work on the appropriate fuel? Lp or natural gas? There is an orfice to change AND an electronic procedure that needs to be done (button pushing) to tell it NAT/LP... Can you be sure this was done?


----------



## CTs2p2

Oh and yes, they will run for about two years before the burner gets burned out.. Maybe that is some of the sediment in the bottom!


----------

