Water heater tank life

[Tony Hwang]

Hi, Under same condition, only comparing tank life, which one would last longer, natural gas one or electric one?

[hallerb]

electrics tend to last longer.

the downside is much lower performance for electric and higher operating cost

[Tony Hwang]

Hi, Thanks.

[Edwin Pawlowski]

Only tank life, electric has an edge, but it mostly likely will burn out an element or two along the way. In most places, gas is cheaper to operate and recovers faster when HW is being used.

[ransley]

If cost per btu of both fuels is the same, or nearly, this is not true. Electric is near 99% efficent, your average gas tank sold is near 50-65% efficent, with the high end on condensing Ng around 80-85% total efficency, known and rated as EF. Recovery or performance is what you buy and need. Gas also loose efficency every year due to scale buildup that does not affect electric units. And how many ever have their burner checked to be sure its burning right. A premium could be paid for electricty and an electric could still be cheaper to run. Every areas fuel and electric costs are different so run your own numbers.

[Blattus Slafaly]

I have tankless point of use water heaters. I am wondering how long they last.

[ransley]

Like my gas tankless the coils are known to last 30 years, its just finned copper pipe, there is no reason for them not to last as long as home copper piping.

[Wayne Boatwright]

On Mon 15 Sep 2008 06:30:56a, ransley told us...

But what about the burner? The products from gas combustion are slightly corrosive and self-destructive over time, yet I'm sure they do last quite a while.

I would think a properly designed electric unit might outlast the gas unit.

[hallerb]

obviously you have never replaced a scale covered electric heater element

[ransley]

What is the point of your statement, I guess you dont realise it is still transfering heat and has nothing in similarity with scale at the bottom of the tank. The electric element is submerged in water, In Ng the heat is outside the tank transfering through metal and scale, the less that transfers the more of your money goes up the chimney. Scale in the tank bottom impeedes heat transfer. Why not google scale - reduced efficency and learn why Ng tanks loose efficency every year. I pulled out a 15 yr old Ng tank that had 12" of hard scale in it, my new water heater cut my bill alot.

[Zootal]

Scale buildup effects gas heaters differently then it does electric. Scale slows down the heat transfer into the water. The hot gas goes by and if it doesn't transfer right then and there into the water, the hot gas is exhausted and the heat energy is vented into the atmosphere. A little bit of scale can make a big difference, and efficiency goes out the window.

With electric heaters, scale buildup on the element slows down the heat transfer from the element into the water. The element gets hotter which increases it's resistance, and less current flows. However, almost all of the heat still makes it into the water - where else is it going to go? Even with old scale coated elements, most of the heat goes into the water and efficiency remains very high. You don't waste electricity, you don't loose efficiency, you just don't get your water heated as fast.

[hallerb]

modern tankless with no pilot light, have complex flame sensors igniters, and monitors.

once a part fails, if its no longer available you are stuck, plus the heat exchangers can clog from sediment.

do not assume a tankless is forever, after all how many newer products really last?

[ransley]

Modern condensing tanks have more complex parts, so does much other heating and cooling equipment, my AO smith has 2 fans, 3 vacume valves, and large circute board, am I worried I wont be able to repair my 2000$ water heater tank, no. These companies will maintain replacement parts just as your furnace, Boiler or AC unit. Hallerb you always do whatever you can to put down Tankless, since you dont have one, go buy one and save up to 30 % in gas off your new unefficent "efficent" unit.

[kmy]

[e-mail] wrote: : On Sep 14, 10:23?pm, Tony Hwang wrote: :> Hi, :> Under same condition, only comparing tank life, which one would last :> longer, natural gas one or electric one?

: electrics tend to last longer.

Don't about you, but my ng water heater just turned 18 this year.

[gfretwell]

It really depends more on the quality of your water than the heat source.

[Phisherman]

Most likely the electric tank, but it will use 2X the operating costs.

[jmeehan]

...

The scale on an electric heater does not reduce efficiency. 100 BTU in water gets 100 BTU In a gas you put 100 BTU (after taking all factors other than scale into account) in you will get less as the scale builds up.

That said, in almost all areas the cost of heating water is cheaper with gas than electric even after accounting for scale.

[Jim Elbrecht]

-snip-

But. . . A scale covered electrode will transfer those BTUs to the water slower than a clean one. [can one of you ashrae engineers check the emmisivity index of copper vs limestone] To compensate for this slower transfer the homeowner will raise the temp of the tank- increasing losses- and making the electric less efficient.

On tank life- get the one with the longest warrantee. Pray. Get lucky. [my cheap LP heater just croaked this week. It was approaching 20 yrs old.]

Jim

[trader4]

Nonsense. If you have a 4500 Watt element submerged in water, where do you think the heat is going while it's waiting to get to the water? If the heat isn't going directly to the water, it would have to be stored somewhere else. And where would that be? Sure, a scale covered element will run slightly hotter, but it's not going to be at all noticeable to the user in terms of how hot the water gets. If it's severly covered or totally buried, it will eventually burn out.