Direct Vent vs Power Vent? Recommended for DIY-ers?

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Shopping for tankless water heater & see e.g. Rheem offers both power vent and direct vent.
Appears the DV models require a 5" stainless coaxial vent pipe . . . more expensive and more complicated.
Does not appear the PV requires the coaxial pipe . . . piping outside air for combustion is optional. So, simpler and cheaper I think?
Downside of PV is use of electricity for blower (when it's running)? How much can that be? Enough to make the added $$ for the expensive coaxial stainless worth it?
I am in West-central Ohio with 47-53 degree ground water.
I can sweat copper and run black pipe for gas . . . is vent piping a "novice beware" job in your opinion?
thx JR in OH
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Unless its a condensing unit double wall pipe may be code as it will be hot, but I was cheap and lazy and didnt use it on my tankless. My blower takes less than 100w if I remember, so figure out your time used, and be sure to measure gas supply with a Manometer with all gas apliances on and calculate in winter mains pressure reductions, or you might hava cold shower next winter.
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Big advantage of not needing electricity is that you have hot water during a power failure. Maybe that's a big deal for you, maybe not. I had a DV water heater (40-gal, not tankless) installed for this reason.
I didn't know tankless heaters were available that don't need power. What ignites the flame when you run the water?
Disadvantage is more expensive vent (as you've noticed) and much tighter restrictions on length, height and bends in the vent, relative to the power vent ones, which can be much further from your outside wall. I had a plumber install mine so I can't comment on the DIY issues.
Chip C Toronto
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My tankless uses 2 D cells for Piezo ignition, some have mini Hydro generators that turn with water flow.
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bari-old-dad wrote:

My State brand PV is 2.8amps on the dilution blower. Exhaust temp is very low. Vented through PVC. A DYI job without problem.
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DYI? Do Yourself In?
It sounds like the power vent is actually a bit simpler to install. Living in NYS, we do power cuts once a year or so. During the winter, a hot shower sure is nice. Well, it's nice during the summer, too. Remember, if you install the power vent model, you'll have no hot water while the power is off.
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Christopher A. Young
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On May 5, 6:11am, "Stormin Mormon"

You can have HW without electricity, you shouldnt of course as a rule. Several times over the years while doing work ive made a mistake of un plugging my tankless blower and forgetting to plug it back in, yes the blower probably is not to code. I took a shower and realised my mistake and went down to check Co on a digital meter and there was none, I believe some gas still vented and the Co buildup wasnt great enough for 5-6 minutes of runninng to register anything on peak level.
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so you admit your install isnt even up to code?
you go mon and on about how wonderful tankless are, not to code makes your info questionable at best, and downright bad info at worst dangerousd.........
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Stormin Mormon wrote:

I'm still not seeing what is going to happen to the 40 or 50 gallons of hot water that are in the tank. And also, who the hell wants to shower in the dark? This argument that you won't have hot water in a power failure just doesn't hold water. <G>
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A TANKLESS HAS NO WATER IN THE TANK!! Because there is NO TANK!
over the years we have had power failures including a memorable 3 day one. some nearby were off over a week:(
you can run a garden hose thru your home, snaking it around ending at tub to provide minimal warmth espically valuable in the winter.
our tank is 75,000 BTU just a tad less than our furnace.
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Sigh. Explaining is such a tankless job.
I heard years ago, about the hot water run slowly through a hose. Sort of like an above the floor Wirsbo system. Very useful, espically in a winter power cut.
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All,
Thanks for the advice. Sounds like I need a pro at least for startup - manual calls for " pipe gas supply but should do pressure test as well.
I have a well so no power = no water, hot or cold. My softener is reliable and effective, so are the caveats about shutdown for cleaning a concern?
Bob that Vertex is a beauty but at $2200 and up I can buy a couple decent tankless models. How much can I write off if I itemize?
I would leave my old 50-gallon electric in place as a "tempering" tank and as a back-up if I go tankless. There is no easy path for a "direct vent" and I need at least 1 45-deg elbow to hit the used-to-be window in the foundation where the furnace's PVC vents go outside.
JR in OH
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If you gas supply is undersized the 2200 bucks might look like a bargain:(
Whats your main interest?
Endless hot water?
Qualifying for federal tax credit?
going green to help the planet?
Last summer a vertex installed at local county fair was $1,100 bucks complete.
the exhibitor had the display model for sale about 900 bucks.
900 was near what a high output standard tank costs the 75,000 btu model. i almost bought his display
check by using a bucket all the same time water uses in your home.
like someone showerting while washer running get a good estimate and to be safe add at least 1/3 but better to double it.
then look at the degrees rise and decide if one tankless will be enough to support the max flow with the coldest late winter water temperature........
the water wasted every time the tankless turns on might matter to you if your well is under sized.......
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I don;t know the specifics of the federal tax credits, but would think a high efficiency tank type probably also qualifies. The credit is for 30% of the cost of the energy efficient unit, installed.
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wrote:

I don;t know the specifics of the federal tax credits, but would think a high efficiency tank type probably also qualifies. The credit is for 30% of the cost of the energy efficient unit, installed.
There are currently no gas tank models that qualify for the credit.
jc
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Left off the source:
http://www.energystar.gov/index.cfm?c=products.pr_tax_credits#c4
jc
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somone should check with AO Smith perhapsa the vertex is in the approval process???
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Thanks for the good info. I see on the list there is no tax credit for solar for pools either. Which is typical of the liberal mentality on these things. One would think, to help save the planet, they would be happy to give a credit for anything that reduces CO2 emissions. But noooo, they just have to make sure that anyone that has enough money to afford a pool, can't benefit. A friend of mine is looking into it for his pool to replace NG. I'm sure it finding this out will at least delay his decision.
It's a shame too, because that is one application that solar is well suited to. Instead of promoting the things that are easy and do work, we are going around paying tens of thousands of dollars for people to put up solar electric systems, which, at the end of the day, will never pay for themselves.

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snipped-for-privacy@optonline.net wrote:

Lots of folks have solar heated pools that they paid for. I don't see any particular reason why I need to help someone else pay to do it.
I agree on PV (and also wind) systems. We happen to live in the second worst place in the US for both and it is just totally stupid for the government to be asking me to help pay for people to install systems that just won't work here just to get the warm and fuzzies that they are doing something. This is just as stupid as last years grinding up food to make ethanol to keep the SUVs going. Just in our state alone they picked $1.2B out of pockets to subsidize ethanol plant construction.

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Of course the same statement could be made for tankless water heaters or high efficiency gas furnaces or AC. Yet, the govt program subsidizes those with a 30% tax credit. The "particular need", at least according to the folks who came up with the subsidies, is to save the planet.

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