I’m thinking about replacing my tank with a tankless. Assuming I go do so, there are two options. 1. Place the new unit where the tank is now (in the middle of a 1 story house) and run roughly 13′ of venting through the attic to the roof. 2. Install the tankless in the attic, running about 5′ of venting (and running water and gas lines up to the attic). What are the concerns here? I’d rather replace the unit where the tank is now. But, will the 13′ vent pipe cause too much condensation, making problems for the unit? I’ve heard that worries about condensation are overblown. I’ve also heard that installing anything over manufact.’s reccommendations is not prudent. What would you do and why? Thanks!
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WHY are you considering a tankless?
Of course it is green and all that, but my experience suggests it's generally not a money saving strategy. For instance, the unit and installation for me last fall cost $3400. That was an easy install. And the venting pipe was about $1,000 of that.
But I did it 'cause I can change my hot water usage behaviors and we (the two of us) are gone at times for extended periods. And, when I sell this place, based upon the energy anaysis, the presence of the tankless (plus a few other changes suggested) counts towards the house having a 5 star energy rating. I figger that'll get me a faster and better price. That's MY payback calculations. Otherwise, it'd be years before I saw any appreciable payback based upon usage alone.
And then, search the archieves. There are volumes and volumes written on the subject there...
And the venting pipe was about $1,000 of that.
How far did you run that vent? FWIW, the vent kit for a Rheem, including everything needed to install the unit on a basement wall and vent it up to 10', is under $200.
FWIW, my tankless HWH and vent kit totalled $700, less the $300 fed rebate, for a net of $400 (plus install, which I did myself).
25' plus a cap.
Course the plumber has kids that need shoes....
We installed an outside-mounted tankless in our home, it's pretty small and unobtrusive and no vents required. It does have a small electric heater to prevent freezing.
I looked into this as well when I replaced for WH last year. I was informed a 1" gas line straight from the meter was required. My meter is in front of the house and the WH was in the back.Needless to say I was not going to run a new gas line. But if I was building or remodeling a house I'd go the tankless route.I do hear the SS ducting is quite expensive and no more than 1 90* is recommended for venting.ML
Now that you mention it, the most expensive thing about the installation was the new gas line - almost as much as the water heater :-(
Here in S. Alabama a 3/4" line is required - the flexible plastic-coated line.
Something to consider w/ regard to placement are the clearances requried for the vent. When my tankless was installed, the 4" vent duct required a 4" clearance from combustibles on all sides, meaning I had to have at least a 12" square chase if I was gonna put it in the middle of the house.
I wound up with mine in the basement, but it was a suboptimal solution IMO, as it's as far away as it could be from the bathrooms (big 2-story) both vertically and in terms of run. OTOH, it's right below my kitchen and laundry. : )
Total cost was $1750 - $900 for the heater, another $850 for the install.
Jason