2 people in the house...thinking of changing out elect water heater,,,thought about gas on demand...I was told HERE that was NOT a good option...why

They work well. Not the ones from the big box stores though. The electric tankless units use massive amounts of electricity, for mediocre results. NG is the way to go. You're probably talking 4-6 times the cost of installing a 50 gal electric water heater.

humm someone posted here before and told me it wasnt a good option with only 2 people...cant remember the reason

Are you willing to lay out that amount of cash?

sure IF its worth it

i'm not a fan of tankless heaters. they are rated in GPM at a specific temperature rise.
in the dead of winter my cold water temperature is as cold as 39 deg F.
so if you want to raise water from 39 to 130, you are talking about about 90 deg rise.
check out the GPM of some heaters when they are working that hard.
warmer climates do not have this problem.

... The electric tankless units use massive amounts of electricity, for mediocre results....

The electric tankless do use massive amounts of electricity when running but so do the gas models relative to gas consumption. A BTU is a BTU no matter what the fuel source and "X" amount of BTU's must be applied to the water to get the desired results. In the end, electric tankless will probably be the most expensive to operate in most locales with LP next and natural the cheapest. Many rural areas do not have the natural gas option.



Edited 1 times.

The math doesn't work for electric....100 amps at 240 volts is only 75000 btu/hr, and you really need to be 150000+

150 amps is more realistic

The good news is.....you can get hot water. The bad news is....you'll cause brown-out in your town, when you take a shower

For 2 people, it may NOT be "worth it". Two people can co-exist with a 40 or 50 gallon conventional heater and the operating costs will probably be the same.

The only gas tankless I would use is the one that has a "preheater" above the main coil which uses the tankless' wasted energy to preheat the cold water.

yea I would go natural gas IF I did it but I will probably just stay with electric on the night rate..

Isnt my 100 amps at 220 volts not 240 ????

220 - 230 - 240


110 - 115 - 120


just a matter of 'rating hype' for the equipment being 'specced[


the only advantage of 'instant/demand' heaters would be the elimination(?) of any 'standby' heat loss from a tank



the instant is way way more expensive
the instant requires major upgrade of the fuel source (if a retrofit)
the instant REQUIRES periodic and SPECIFIC maintenance such as descaling

'down the road' parts and service may be problematic

imo: no advantage for two or three person household - especially considering that a low/small draw may not even 'fire' the unit - your state of the art low-flow shower may not even 'call' for HW, so you need to draw MORE HW to get the thing to work

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Most power is 240 volts these days, but you would still need 100 amps or more. You get about one gallon per hour per amp, which is therefore, about 1 1/2 gpm for 100 amps.

if the power co is actually supplying 110 then you would have 220

my home gets 117VAC which means my dryer is actually getting 234VAC (not counting voltage drop when actually running)

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

how would I know ?

unless you actually measure the voltage you would NOT know

however

it really does not matter as a practical matter

as long as

it is between 105 and 125

perfect would be 115VAC @ 60Hz

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

I doubt that any power company is still producing 110/220 at the transformers.

so I would put a volt meter on the incoming ?

Ok I just checked it at an outlet and its 115.5 volts...so my main poer would be 230 right ?

Three points that haven't been raised.

One major advantage of a tankless is space. If you need the space currently occupied by a large tank, then it may be worth it.

If you go with gas, it needs to be vented. That's additional $.

With a tankless heater, if a hurricane strikes and power is out, you have INSTANT cold water. With a heated tank, you have another 50 gallons or so before it runs out.

yea space is no problem....I just think I will stick with the 80 gallon electric on the off peak meter...the rate is better...there is only two of us but I think if if I wnet with a 40 on a day meter it may cost me more....our bills run about 100.00 gas and elect in the summer....about 150.00 gas and elect in the winter...1300 sf ranch...some people pay more than that for a cell ph

correct

remember: 220 is the same 'rating' as 230 which is the same 'rating' as 240

since: amps = watts/volts , a 10% difference in volts will have some but not much effect on amps


it is all 'nominal' ratings just like 1/2" iron pipe size is not exactly 1/2"

from memory: the typical domestic water heater is rated about 4500watts / 20amps and is serviced by a 30amp breaker

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

a day meter WILL cost more because although you will use the same amount of electricity the heater will operate when the hot water is being depleted, rather than when the meter says it can.

obviously.

Yes unless you have 3 phase power into your house. The place to check is at the circuit breaker panel across the two main feeds.

VERY VERY VERY VERY CAREFULLY

NOT RECOMENDED FOR AN AMATEUR OR DIYer

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

quote; NOT RECOMENDED FOR AN AMATEUR OR DIYer

And would you say that someone who does not know how to test for the line voltage in the first place would be an "amateur"? The "Darwin Awards" celebrates those who are not capable of doing it correctly.

for the less educated:

a short after a circuit should result in a 'pop' followed by the almost instantaneous 'tripping' of the breaker

a short on the main 'bus-bar' supplying the breakers will result in a 'boom' and will NOT shut down until either:

the shorting thing melts or dies

OR

a class "D" fire (burning metal) occurs

SINCE

there is for practical purposes virtually unlimited amperage available (NO LOCAL BREAKER)

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

232.8 volts at the incoming line at the panel....I had my wife do it

so...if I wanted to check amperage I would use an amp meter clamped around each of the incoming legs and add the two numbers together ?.....dont worry im careful....

a 4500 watt @ 230 vac water heater element 'draws' 19.5 amps

i would presume each 'leg' would draw 9.75 amp @ 115

using this logic:

at the breaker panel, using a 'clamp around' ammeter

the measurement at each 'leg' would be [ xyz AMPS @ 115 VAC ]

adding the two amp readings together would result in: zyx amps @ 230 vac

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 1 times.

quote; a short on the main 'bus-bar' supplying the breakers will result in a 'boom' and will NOT shut down until either:

The "bus bars" are AFTER the "main breakers" and WILL shut down when they trip.

quote; I had my wife do it

The farmers in VietNam used to ride their donkeys and the wife walked behind him. When asked why they did it, the reply was, "It is the custom". Now the wife walks ahead of the husband who is still riding the donkey. When he was asked why the change, he replied, "Landmines".

The amperes at each leg IS the amperage at THAT voltage. You do not add them together. I am getting the impression that maybe we should take your multimeter away from you before you do serious damage to yourself.



Edited 1 times.

you are assuming the existence of a 'master' breaker

not all panels are protected by a (master) 200 or 100 or 150 AMP breaker

as for the total amperage I was trying to explain how one would arrive at a total actually used 'through' the panel as a whole as opposed to 'adding up the breakers'

eg:

water heater element

10amp at one 115vac leg + 10amp at other 115vac leg = 20amp actually 'drawn' at 30amp / 230vac breaker

hj, give it a rest POR FAVOR



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



Edited 1 times.

quote; not all panels are protected by a (master) 200 or 100 or 150 AMP breaker

I am waiting to see my first one. IF you just add up all the breakers, you will come up with a total WELL beyond the rating of the panel. Eleven 20 amp breakers exceed 200 amps.

try South Carolina code pre 1996

(pre 1996 local code NOT NEC was used)

did NOT require a 'master' breaker

? what on earth makes you believe that ACTUAL 'rural USA' construction is/was any better than, shall we say, Peru or Argentina ?



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Around the 60s they did not require a T&P valve for electric water heaters either, because they were "as safe as a light bulb". But you are saying that at that time there was NO WAY to isolate the electric panel from the electric meter. I'll take your word for it, but I am sure the power company was not happy about it.When they install the meter, they usually like to have a "main switch" to turn off before powering up the system.

there is a 'main switch' at/near the meter location (in an enclosed weathertight box)

BUT

it is a switch only, NOT a current 'limiting' circuit breaker



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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Most "main switches" also have cartridge fuses, not circuit breakers, in them.

nope - no current limiting/cutoff of any type (at least not in my subdivision)


in Newburgh, NY (my old home) not even a switch - power went from meter box direct to panel


this situation is the reason a type "D" electrical fire can occur


type "D" fire = burning metal


not really familiar with post 2001 construction standards / code


we have been "BSed" most of our lives as to construction standards / quality


check with your local FD for further info

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Smart let your wife do it