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

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

Reply to
bari-old-dad
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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.

Reply to
ransley

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

Reply to
Chip C

My tankless uses 2 D cells for Piezo ignition, some have mini Hydro generators that turn with water flow.

Reply to
ransley

My State brand PV is 2.8amps on the dilution blower. Exhaust temp is very low. Vented through PVC. A DYI job without problem.

Reply to
Steve Barker

Hey thankless have many downsides, with your low incoming water temperature you might need 2 tankless in series to heat enough water. Low flow may mean no hot water at all:( Plu buy a tankless with a local knowledgable dealer they are more complex and will likely need regular service, to remove hard water buildup.

standby loses of regular tanks are actually pretty low, you may not save much and the payoff may be longer than the tanklesses useful life...........

just some things to consider while spending large amount of money

Reply to
bob haller

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.

Reply to
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.

Reply to
ransley

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.

Reply to
Steve Barker

wants to shower

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.

Reply to
bob haller

If you are set on tankless, I would go with a direct vent. There are a couple of reasons for this. First, if you find yourself having to powervent, it may be cheaper to just move the tankless HWH to a spot where you can direct vent and replumb since you have the ability to sweat copper. There are two savings here: the double walled stainless vent pipe isn't cheap and the powervent tankless HWH is more expensive than the DV one. Secondly, as others have pointed out, there's no stored hot water, so if electricity goes out to the vent blower, you won't have any hot water.

HTH,

jc

Reply to
Joe

ide quoted text -

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.........

Reply to
bob haller

OP will need gas pressure flow tests, before install, and likely a new gas ine directly from meter to install spot.

that might make a power vent heater cheaper install wise.

*That* is a good point. I was assuming (yeah, I know) that the OP was going to do the gas line work himself. That, as you said, does not address the flow test, however.

jc

Reply to
Joe

flow test must be done carefully.

adquate flow must take into consideration other loads espically a furnace running, and cant forget cold incoming winter water temperatures....

basically what works fine in mid summer may be a complete failure in mid winter.

and ransley crows how well his works, while admitting its not to code.

Reply to
bob haller

flow test must be done carefully.

adquate flow must take into consideration other loads espically a furnace running, and cant forget cold incoming winter water temperatures....

basically what works fine in mid summer may be a complete failure in mid winter.

and ransley crows how well his works, while admitting its not to code.

ransley crows about too much, which is why he's in my killfile. jc

Reply to
Joe

I don't have the original post, but I thought it was a low capacity instant heater. Best of luck showering with 2 galons of water contained in the tank. I had a 12 gal WH years ago, and that made for quick showers.

So, shower daytime with sunlight coming in. Or, take a candle in the shower.

Reply to
Stormin Mormon

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.

Reply to
Stormin Mormon

All,

Thanks for the advice. Sounds like I need a pro at least for startup - manual calls for =BE" pipe gas supply but should do pressure test as well.

I have a well so no power =3D 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

Reply to
bari-old-dad

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.......

Reply to
bob haller

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.

Reply to
trader4

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