24" vent, 80' tall

Dan Foley

We recently replaced this commercial flue that vents the steam boiler. The existing 40 year old vent pipe had rusted out.

We don't typically do this type of work but the condo board wanted us to do this as we have already replaced the steam boiler and DHW system in this building.

A mechanical engineer designed and specified the vent system. Luckily for me my rep was looking out for me as the engineer had specified a product that was not rated for outdoor use. My rep specified a suitable vent system and the condo board agreed to pay the difference.

It really should have been insulated stainless steel but they did not want to pony up the additional $$.

bob eck

Job looks great.
What is the other pipe looks like InnoFlue or a product like that. What does the other flue vent?

Dan Foley

Thanks, Bob

The other flue is 8" Centrotherm.

It vents two Viessmann boilers serving the DHW system.

Tinman

Dan - On the Centrotherm, is there any concern for condensate freezing? The reason I ask is that we had to do something very similar to that recently. I was very concerned about icing but we recently went through some sub-zero temps without problem.

Dan Foley

Steve,

I had similar thoughts but this was specified by the engineer and approved by the manufacturer.

Our weather here in DC is milder than your climate. It would be hard for an 8" pipe to freeze over.

bob eck

Dan I take it Centrotherm is UV resistant?

Dan Foley

Yes, this is something I checked with Centrotherm. This product is UV stabilized per their submittal.

Derheatmeister

Dan, I did not think that the Grey PP Centrotherm should be exposed Directly to UV light ....They also sell the UV stabilized Black Centrotherm ..We only expose the Black pipe on the exterior and always keep it to a minimum because of the freezing of condensate here in the high Country.
As per the Installation Instructions Innoflue can also be painted. The use of an adhesion promoter that is specifically recommended for use with polypropylene is also allowed.
Also: Does Viessmann now allow Common venting of two boilers into one Vent?
Maybe i am confused .
Richard

Dan Foley

Hi Richard,

Good points but not accurate. Viessmann has a cascade common vent kit for the Vitodrns 200 as we used here. It was designed and approved by Viessmann.

The vent system was designed by Centrotherm. The submittal clearly states that it is uv stabilized and approved for outdoor installation. I will see if I can attach both submittals when I am in the office tomorrow.

Maybe you are confusing this. commercial size vent with the smaller residential size Centrotherm vent?

I appreciate your sharp eye.

rick in Alaska

So what did you use for scaffolding to put that all together. Were you able to do it from the staircase? Looks challenging.
Also looks great!
Rick

Dan Foley

@ rick in Alaska

We had scaffolding set up to the roof level to facilitate the vent replacement. It was not possible to work safely from a ladder or from the fire escape.

Dan Foley

@ Derheatmeister

Richard,

Attached is the Viessmann common vent spec sheet.

Dan Foley

@ Derheatmeister

Richard,

Attached is the Centrotherm submittal (Client info blocked out).

This vent system was designed by Centrotherm. The local rep was on the job to confirm site conditions.

Henry

Is the B-Vent certified for exterior use? It will rust out in a few years. We do not permit this. But the local AHJ can in your area.

Zman

"It really should have been insulated stainless steel but they did not want to pony up the additional $$"

This was my first thought when I saw the pics. I am curious if there are any winter days where the condensate drain does not run. What material is the big flue.

Great workmanship as always.

Dan Foley

It is certified for outdoor use by manufacturer. The vent specified by the engineer was not. This error was caught by my rep.

The old B Vent was not rated for outdoor use but lasted 40+ years.

Remember this was designed and stamped by a mechanical engineer. If I designed it, I would have specified stainless steel.

Dan Foley

@ Henry

This job was in DC. The plans were approved by permit office. It passed final.

The product we ended up using is approved by the manufacturer for outdoor use.

ChrisJ

Dan Foley said:

It is certified for outdoor use by manufacturer. The vent specified by the engineer was not. This error was caught by my rep.



The old B Vent was not rated for outdoor use but lasted 40+ years.



Remember this was designed and stamped by a mechanical engineer. If I designed it, I would have specified stainless steel.

The last vent that wasn't even rated for outdoor use lasted 40 years, why spend a ton on Stainless Steel?

Dan Foley

Lol. Agreed Chris.

My name is on the company. That's why.

The old vent served its purpose but stainless would have been the better choice. But you don't always get what you want.