How Could This Happen?

Mike T., Swampeast MO

Not even any guesses?

I can easily believe that the water in the basement piping (big gravity pipes) was below ambient air temp in the basement, but hard to imagine too far below.

It was a very humid day as it had rained overnight and rained again later after the work was done. Unusually warm, but not particularly cold on days before.

When I removed the combustion chamber cover, the outside of the combustion chamber was bone dry and it stayed that way until <I>after</I> the boiler had fired for at least 30 seconds.

Then then <I>entire</I> outside of the combustion chamber--sides <I>and front</I> were covered in "dew". The dew grew and drops of water were falling to the bottom (fortunately there's a drain--hmmm) within a minute and continued until I shut down the boiler after about 2 minutes of firing and replaced the cover.

Had utility man feel the supply pipe--hot. Had him feel the supply pipe leading to the one rad whose TRV I'd opened--nice and warm.

I think that the only "water jacket" in the Vitodens is at the rear of the cumbustion chamber--not around the sides--and CERTAINLY not at the front.

It sure seems to me that the stainless steel surrounding the combustion chamber actually cooled when the boiler was firing <I>at maximum output</I>...

When you look at other mod-cons and see insulation--<I>anywhere</I>--you should remember that the Vitodens has none--because it doesn't need any...

This is NOT a Viessmann commercial. People keep asking, "What makes it different?" I guess I'm just the sort of geek who spends time observing the observation of boilers (and I spent MANY, MANY hours with the old cast iron cube). Hell, I've spent quite a few hours of my life watching clothes washing machines.

I grew up in a home business--secretarial, telephone answering and printing--with <I>lots</I> of machines. Watching...learning...<B>repairing</B>.

The Vitodens is truly the most amazing and enigmatic machine I've ever seen. Connect it to a system that can <I>instantly</I> absorb its output and it does things that shouldn't be able to happen.

Mike T., Swampeast MO

A month or so ago, the main gas line serving my house was replaced--not the branch--just the main.

I'd left them a note saying that if they made the new connection with temps below 55F to let me know first so I could turn off my boiler to keep it from finding a fault.

Unusually warm day--easily 60--when they changed.

Utility company rep came in to check things out after the change.

While he "force fired" the water heater, I was opening the Vitodens and removing the combustion chamber cover. He thought it was an "instant" water heater...

I opened one TRV and set the boiler to "test" where it fires at full ouput. No fault and after at least 1 minute I had him touch the outside of the surface that directly surrounds the combustion chamber. Cool! Told him it was firing at about 90 mbh.

The OUTSIDE of the combustion chamber was covered in condensation! Basement couldn't have been more than a few degrees warmer than the outside temp yet condensation was still forming on the OUTSIDE of the combustion chamber--and there ain't no insulation between the outside and the inside--just that incredible heat exchanger...

Is this yet another "Vitodens difference"?