Condensation in chimney--next step?

dpschuste

Hi everyone, we built a new house. Amish mason built a beautiful chimney with 2 12" terra cotta flues--one for the fireplace (good) & one to vent the high efficiency buderus propane boiler & water heater (bad). B/c flue is over-sized, condensate is leaking back into our house (not living there yet)--of course have learned all this the hard way on the internet over the past few weeks
Options now seem to be:
1. install a stainless, insulated 5" chimney liner down the 30' chimney & hope there is enough draft to fix the problem; or
2. Add power-vent straight out & just leave the original flue empty.

My specific questions are:
1. Preference between the 2 options--or any other I am missing?
2. Any suggestions re: product we should use for that 5" insulated flue? Scared to trust my mason/chimney builder to get that right;
3. Thoughts on the power vent? My heating guy says they are loud, difficult to service & that repairs are frequent.
I would be grateful for any/all feedback!

Zman

What model is the boiler?

SuperTech

High efficiency propane boiler? Sounds like that would utilize a PVC flue pipe.

bob eck

Check and see if the Buderus boiler can be vented with polypropylene chimney liner kit form Innoflue or Polypro
That is made for condensing natural gas or LP gas boilers

newagedawn

add the liner, the home builder or heating contractor needed to know what system you where installing, then the mason could have made a 6 by 6 chimney flue to accommodate the appliance, buderus are the cadilac of heating, enjoy your savings

lchmb

Line the chimney... What model boiler are you using?

Bob Harper

When building it would have been easier and much better to install a listed venting system. He could have installed 6" insulated stainless steel chimney that doesn't need surrounding masonry unless desired for aesthetics, construct a single wythe brick chimney but instead of obsolete terra cotta, line it with a listed stainless steel liner and a condensate trap. Any of these should have excellent draft, condensate containment with male-down joints ease of inspection and maintenance and a lifetime warranty. Some liners have transferrable forever warranties. See your local chimney pro.

DZoro

You mentioned high efficiency, what is the model number of the boiler?

Zman

@dpschuste
You have 2 identical posts going with several responses each.
What model is your boiler?

dpschuste

Thanks for the responses.
Model is Buderus GC 144-25/4 II
SuperTech--From reading other posts on this site, I thought this would require a stainless steel insulated flue?

dpschuste

Thanks for the comments everyone. Model is Buderus GC 144-25/4 II
No doubt we missed an opportunity, but sounds like you are still all leaning toward retro-fitting the chimney with a proper liner. Insulated stainless steel--any other suggestions/things to be aware of? Brands you prefer? Reaching out to my local chimney guy now--hard to know if he's good?

SuperTech

> @dpschuste said:
> Thanks for the responses.
> Model is Buderus GC 144-25/4 II
> SuperTech--From reading other posts on this site, I thought this would require a stainless steel insulated flue?

I was just taking a wild guess. Usually when I hear high efficiency and propane together that would mean a modulating condensing boiler. I usually see those with a PVC flue pipe and combustion air intake pipe.

I don't recognize your particular boiler by the model number, but I'm sure the manual would explain what type of venting is required.

GBart

AYE..........GOLD STAR TO SUPERTECH.............USE THE MANUAL!!!


insert GIF of person hitting their head against the WALL

dpschuste

This manual is hard for a non expert to navigate due to many references back to the NFGC. For ex: "An adequate chimney height in compliance with the tables of the National Fuel Gas Code, ANSI Z 223.1, is required." Just trying to get some quick, general layman's info so I can make better, more-informed decisions. Leaving this entirely to my heating "expert"--who HAS the manual & presumably the NFGC--hasn't worked out so well thus far.

HVACNUT

That is an atmospheric boiler. It needs the stainless liner. I dont believe Buderus options a power vent for that application.
Why wasn't any of this caught when the contractor checked the prints? Seems like there was absolutely no coordination between the architect, owner, chimney guys and heating contractor.
Sometime it pays to not be your own G.C.

Bob Harper

The boiler needs a listed stainless steel liner. It is not required by national codes or the listing to be insulated but there may be some value depending upon your climatic zone, whether indoor or outdoor chimney, length of lateral offset on the vent connector (single walled galvanized steel "stovepipe"), etc. Note it must be at least a 5" nominal liner. However, corrugated liners must be de-rated 20% off the bat plus more for offsets except the 90° turn at the base. Here I would install a stainless steel tee as a condensate trap. If you run the connector male-down to the boiler it will be drip-free. This is not a DIY project so hire a pro. Any good liner will carry that transferrable forever warranty. Get 316Ti alloy ss at least or AL29-4C if it is an exterior chimney.

captainco

I know we like to blame chimneys for things they can't do because they are inanimate objects. But is it possible the real problem is that there may be a venting or combustion air problem? A liner will not fix either one.

dpschuste

I was not the GC. But the GC did leave it to the heating contractor & chimney guys to work together &, apparently, they did not. Plenty of blame to go around, but trying to be solution-centered.
Bob, thanks for the specific, helpful info. Started calling around to chimney experts--vs just my stone-laying mason--yesterday. Will use your post to help me be sure this one knows what is needed.

GBart

dpschuste said:

This manual is hard for a non expert to navigate due to many references back to the NFGC. For ex: "An adequate chimney height in compliance with the tables of the National Fuel Gas Code, ANSI Z 223.1, is required." Just trying to get some quick, general layman's info so I can make better, more-informed decisions. Leaving this entirely to my heating "expert"--who HAS the manual & presumably the NFGC--hasn't worked out so well thus far.

I wasn't referencing you, but all the installers and many people here tend to go into advice mode and there is only one answer, it's in the installation manual for that particular unit period, anyone giving anyone off the cuff advice is wrong.