Most efficient water heater?

I'd like to switch to a direct vent water heater. Looking at the A.O. Smith site I get confused with all the models. Efficiency information is hidden. There is no convenient chart to distinguish the models. It would seem that these are my choice:

ProMax Closed Combustion Power Direct-Vent ProMax Power Vent (C3 FVIR) Power House Sealed Shot Power Direct-Vent Power House Power Shot Power-Vent

But I can't figure out what is different. Plus each of the above has variants.

So, what is the most efficient 50 gallon tank water heater with the longest tank warranty? The run would be about 40 feet and will have a bunch of 90 degree bends.

Don (e-mail link at home page bottom).

Reply to
Don Wiss
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You forgot the Vertex Power Vent water heater at 90% efficiency The Promax Closed Combustion Power Direct vent means you have 2 pvc pipes. One brings air in for combustion. The other pipe vents the flue gasses out. The Promax Power vent C3 FVIR is just a single pipe water heater with the technology to stop gasoline tank vapors from exploding due to those retarded people that like to store paint and gas cans next to their water heater. Goverment required. The Power House sealed vents further and has two pipes. The Power House Power Shot is a single pipe that vents further. All those have 6 year tanks and parts The vertex is going to be the most efficient and the most expensive to purchase. Bubba

Reply to
Bubba

Most efficent is tankless since efficency is misleading, the Energy Factor is what has the most meaning in water heaters , gas tanks of regular vent and 80+% efficency are around 50-60 energy factor, i dont know about direct vent though, tankless start around 80 energy factor.

Reply to
ransley

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tankless have lots of downsides, from delay when you fiorst draw water till heated water arrives, to poor operation at low flow levels.

standard tanks actually have very low standby losses, just got touch your tank hot hot is it?

current hoigh efficency condensing tanks are over 90% efficent. that should be enough for anyone

Reply to
hallerb

Whatever you have now, keep it.

Just had to replace a direct vent and estimates were all around $1400 with just a 6 year tank warranty. Electric would be less than 1/3. I decided to go with an on demand system to replace the direct vent. It cost around $3k but at least had a 12 year warranty and normally lasts 20 years.

If you go with a on demand system, consider having the gas company doing it. Tons of things had to be done including replacing the gas meter. Get a unit that has a low flow start rate. Stay away from Bosch.

The downside is that the hot water tank was apparently keeping my basement warm and warming the cold water. So now that cold water in my house is much colder and so is my basement. An advantage during the summer, disadvantage during the winter. That is why people think it takes longer for hot water to show up.... cold water is much colder with an on demand system.

Also if system isn't installed right or you buy wrong one you will get inadequate flow rate. It gives you unlimited hot water but not immediate or unlimited flowrate. There are compromises. I like the idea of no tank though.

Reply to
Art

That's not really true, a standard 80% combustion efficient tank heater has an energy factor of around 0.60, so of the theoretical heating value of the fuel burned, 20% goes up the flue, and the other

20% is roughly standby losses from the tank. Even an electric tank water heater, which has a 100% "combustion" efficiency has an energy factor of 0.91-0.93, so 7%-9% of the energy is lost as standby.

Also, a conventional tank water heater has most of its standby losses up the flue, which travels through the middle of the tank. This is why the standby losses are much higher than an electric tank. You wouldn't notice this by touching the outside of the tank.

Combustion efficiency is not the same as energy factor. AO Smith doesn't have an energy factor rating for the Vertex, they say that anything about 65,000 BTUs/hr input doesn't need to get rated. One can guess that the standby losses are less than a conventional water heater (due to the helical flue in the Vertex), but still more than an electric. So the energy factor is maybe 0.75-0.80.

For a tankess gas water heater, the standby losses are zero, so the energy factor is equal to the combustion efficiency. So an 80% combustion efficient tankless has an energy factor of 0.80.

Yours, Wayne

Reply to
Wayne Whitney

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Hallerb , have you used a tankless, no I will bet not, you put them down because you cant afford one and have never used one. The delay in hot water arriving might be 5 seconds longer than a tank since it fires in seconds. 90 % efficent , yea the burner is, so how can you explain 50-60% Energy Factor on tanks and 83-90 on Tankless. As I said thats more of a true efficency rating, so what if the tank isnt hot, what do you think goes up the middle of the tank and out the chimney, heat!

Reply to
ransley

I'll put them down. AND I CAN afford them. All i have to do is ask you what is the maximum temperature of your hot water in the winter, when the incoming water is about 39 degrees? There, the argument is over. There's NO WAY you can get 140 degree water from 39 degree input with a tankless. And you can't wash dishes properly with 98 degree water. Hell, I'll bet with 39 degree input, you can't even take a decent hot shower with all hot and no cold on.

steve

Hallerb , have you used a tankless, no I will bet not, you put them down because you cant afford one and have never used one. The delay in hot water arriving might be 5 seconds longer than a tank since it fires in seconds. 90 % efficent , yea the burner is, so how can you explain 50-60% Energy Factor on tanks and 83-90 on Tankless. As I said thats more of a true efficency rating, so what if the tank isnt hot, what do you think goes up the middle of the tank and out the chimney, heat!

Reply to
S. Barker

Yes there is.

The whole reason I wrote up my water heater saga was so that others benefit from all the help people here gave me. One of the references in the thread was the recent DECEMBER 12, 2007. CONSUMERS' DIRECTORY OF CERTIFIED EFFICIENCY RATINGS for Residential gas, oil, and electric water heating equipment.

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11 Feb 2008 10:54:32 EST

In that reference PDF are the efficiency ratings for the hundreds of residential hot water heaters sold in the USA (under a handful of manufacturers but scores of brands).

I challenge you to find a water heater efficiency rating NOT in this

36-page listing for a water heater currently sold in the USA.
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Reply to
Donna Ohl

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$FILE/12-07-gas-rwh.pdf Where's the A.O. Smith Vertex model GPHE-50 that Bubba recommended?

Don (e-mail link at home page bottom).

Reply to
Don Wiss

Here we go again, sombody who does not have a clue to the facts, has not used one, but can give false information putting them down. I have a water main incomming on a hill which is too close to the surface since dirt is going away, when its -10f out my incomming has gotten to

34f. I dont even have my small 117000 btu Bosch on high and the shower is great. Look at specs, 90f rise is what you can get, 130f water is to hot and a waste of money. 98f with 39f incomming is only 59f rise, far short of 90f rise which my unit does, and I have measured it. Consider something else, Tanks loose 1-3% efficency every year due to scale buildup at the bottom of the tank, I recently removed a maybe 25 yr old tank with 13" of rock scale in it, I bet it was only 50% efficent, Tankless dont hold scale, Tankless you just pur in Lime Away through a valve you add, a simple 30 minute procedure to keep it 100% efficent 25 years down the road, you cant clean out most tank units. Tanks loose efficency every year and you cant stop it by flushing it.
Reply to
ransley

I saw one unit near the bottom with an Energy Factor of 70, only a few in the 60s and most in the 50-60 range. Vertex, I have a several year old similar AO condensing ccommercial unit but I only know its 92% efficent or so

Reply to
ransley

Here we go again, sombody who does not have a clue to the facts, has not used one, but can give false information putting them down. I have a water main incomming on a hill which is too close to the surface since dirt is going away, when its -10f out my incomming has gotten to

34f. I dont even have my small 117000 btu Bosch on high and the shower is great. Look at specs, 90f rise is what you can get, 130f water is to hot and a waste of money. 98f with 39f incomming is only 59f rise, far short of 90f rise which my unit does, and I have measured it. Consider something else, Tanks loose 1-3% efficency every year due to scale buildup at the bottom of the tank, I recently removed a maybe 25 yr old tank with 13" of rock scale in it, I bet it was only 50% efficent, Tankless dont hold scale, Tankless you just pur in Lime Away through a valve you add, a simple 30 minute procedure to keep it 100% efficent 25 years down the road, you cant clean out most tank units. Tanks loose efficency every year and you cant stop it by flushing it.

YOu stupid f*ck in the perfect whirl heat is either gained or lost at the toilet depends on how warm your turd was and incoming water temp.

Reply to
Jeffrey Lebowski

AO Smith has the Vertex water heater that gets 90% Weil-McLain has a boiler that does 98% at low temp Bubba

Reply to
Bubba

92-93-94 even 98% water heaters are common even 96% boilers, even a 94% tankless. AO Smith Cyclone tank, Takagi tankless and a Canadian firm makes a 98% commercial hw boiler, 5 years ago I installed at my apt a 92% 1900000 btu AO Smith Cyclone. these are all condensing units,
Reply to
ransley

on a tankless feeding a regular tank, it should cost no more to operate than a regular hot water tank.

the tankless initially heats the water to whatever it can, then sends the water to a regular tank that does its normal job.

endless hot water regular tank conveniences and the only extra cost is the line between the tankless and regular tank, ideally it should be short and well insulated.

true the tank will have normal tank losses.

today i have to stop at home depot and while i am there price some hot water tanks. just to verify some of these issues:)

Reply to
hallerb

Maybe not, but is sure costs a lot more in terms of buying and installing 2 water heaters, one of which is tankless and more expensive. With this approach, you incur the higher cost of tankless and by having the second regular tank, you still have the standby losses, which defeat most of the advantage of the tankless that justify it's expense. I fail to see the point. Plenty of folks have a gas tankless for their whole house needs and are happy with it.

Reply to
trader4

There is no point to this approach, its backwards and will loose you all the savings you just paid for. If the tankless and tank are 82% efficent you are heating with one 82% burner and keeping it warm with another 82% burner. You are heating with the tankless and allowing it to cool in the tank, at about a 20% reduction in efficency rating. Most of what you just paid for in increased efficency goes up the center of the tank and out the chimney. The tank if hooked up should before the tankless and only hold water unheated to allow it to warm up by the surounding air to temper it, it works for me. Even better is to strip of the insulation on the tank, your basement will always be warmer then the incomming water main.

Reply to
ransley

For pricing a tank look at a cheap uninsulated well tank.

Reply to
ransley

If you're gonna spend lots of money on a water tank you might as well get an oil fired demand water heater. Gives you unlimited hot water and no cost to maintain a tank of hot water. If you want to put a tempering tank in your hot attic save even more.

Reply to
Blattus Slafaly

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