Author Topic: Orphaned hot water tanks  (Read 763 times)

Offline Hgye

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Orphaned hot water tanks
« on: October 15, 2016, 08:13:44 AM »
I always drop a 4" liner for orphaned hot water tanks but someone just told me that I don't always have to.  They said you can leave up to a 6" chimney in place.  Does anyone know what they are talking about?

Offline Porcupinepuffer

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Re: Orphaned hot water tanks
« Reply #1 on: October 15, 2016, 08:44:23 AM »
Been a little while since I've done this, but in situations where we would install a new furnace to high efficiency, we'd often end up dropping in a liner on an existing natural draft water heater only when the chimney is located on the outside wall. If the chimney was running up the middle of the house, there would be no issue of the flue temperature falling below dewpoint. I think the only situation with a chimney on an outside wall without running a smaller liner was if it was a b vent running down an old chimney. I believe in that situation it ends up being insulated enough to not suffer any condensation issues.

We've also came across some oddball situations where the chimney was half in a garage, or mostly going up the middle of the house and then a good portion of it ends up being exposed outside at higher levels. I suppose due diligence comes into play at some point and tossing in a liner saves headaches and head scratching.

But anytime you're looking at a chimney against the outside wall that's brick/clay tile, it's a given that you'll need to drop a 4" liner.

Now I'm curious to go digging through the codebook.

Offline Admin

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Re: Orphaned hot water tanks
« Reply #2 on: October 15, 2016, 10:03:21 AM »
Download the TSSA Advisory FS-065-05 here,

http://www.hvactechgroup.com/article.php/20070429181100239

Download the TSSA Advisory FS-110-07 here,

http://www.hvactechgroup.com/article.php/20071130200551500