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-   -   Tankless water heater vs. electrical water heater? (http://www.diychatroom.com/f18/tankless-water-heater-vs-electrical-water-heater-26312/)

imola ghost 09-05-2008 09:58 AM

Tankless water heater vs. electrical water heater?
 
I'm considering replacing my 55 gallon electric water heater. Though I won't do this myself but wanted to know what kind of savings I would see vs. going the conventional water heater style?

I've heard that using a "electric" tankless water heater was not as efficient as a conventional water heater but rather a gas tankless was the way to save. I don't have a choice as my area doesn't have gas. Now this was something I heard so I cannot confirm whether its true.

If someone has some information about this subject I'd love to hear about it.

SD515 09-05-2008 11:11 PM

I can't reply on an electric tankless, though I would imagine there could be a savings since the htr only heats water as it passes through it, where as a tank will cycle on & off all day just keeping water heated, in case someone needs it. I know the gas versions use less gas and save money. But either way because of the initial cost, it's a few years down the road before you 'break even'.

J. V. 09-06-2008 11:58 AM

With electric tankless water heaters you have to take into account the installation cost. You will need at least 2 - 40 amp circuits installed for a whole house system. The last one I looked at required 3 - 40 amp circuits. Homeowners that do not have at least a 200 amp service panel will require the upgrade to 200 amp in most cases, or the addition of a sub panel.. These TWH's are power hogs to say the least. It is true that they only use power when hot water is needed, but if you look at the WHOLE picture, you will most likely never recoup the investment.
I did some research on TWH's and have decided I will never install one in my house. But I would install one in your house.

I do like the idea of using TWH's for point of service use. Like a small one under the kitchen sink for the sink and dishwasher. But not for the whole house.

jimmy21 09-06-2008 09:10 PM

Quote:

Originally Posted by J. V. (Post 155594)
I did some research on TWH's and have decided I will never install one in my house. But I would install one in your house.


would it be worth it on a new house?

There is also always special circumstances, like my dads office that has a shower, no one ever showers there, so it might be a waste to have a full hot water heater hot all the time. Or it would also be nice if you had a whole family that wanted to shower in the morning and not run out of water

But like me, if i had to replace mine, i might consider tankless, because i wouldn't be paying labor, and i get materials at a discount and some material free. Would i come out ahead over just replacing a conventional water heater?

J. V. 09-07-2008 10:28 AM

Quote:

Originally Posted by jimmy21 (Post 155752)
would it be worth it on a new house?

There is also always special circumstances, like my dads office that has a shower, no one ever showers there, so it might be a waste to have a full hot water heater hot all the time. Or it would also be nice if you had a whole family that wanted to shower in the morning and not run out of water

But like me, if i had to replace mine, i might consider tankless, because i wouldn't be paying labor, and i get materials at a discount and some material free. Would i come out ahead over just replacing a conventional water heater?

In new construction it might be the way to go. In this case the cost of installation will not be felt immediately.
If you are changing from standard to tankless, you have a good bit of electrical work to do. So if you can do it yourself and get good pricing, go for it.
My point is the way the TWH's are marketed. They tell you about the savings and how it only comes on when needed. They don't tell you how much goes into the install.

Your dads office would IMO be a good candidate for the tankless. So would a small one for the kitchen or maybe a bathroom far away from the tank. You do not get hot water any faster with tankless, unless you install it at the point of use.

imola ghost 09-07-2008 10:56 AM

I can pick up a Rennai brand, I think it will provide hot water to 4 showers simultaneously for around $400. I have and easy run (electrical) to my fuse panel, which I could run the electrical and then have the installer finish the work.

Cow 09-07-2008 01:10 PM

Quote:

Originally Posted by imola ghost (Post 155881)
I can pick up a Rennai brand, I think it will provide hot water to 4 showers simultaneously for around $400. I have and easy run (electrical) to my fuse panel, which I could run the electrical and then have the installer finish the work.

I would absolutely have a load calculation done on your service before you buy an electric twh. Like stated above, they draw BIG power for short periods of time.

YerDugliness 09-07-2008 05:04 PM

Quote:

Originally Posted by imola ghost (Post 155881)
I can pick up a Rennai brand, I think it will provide hot water to 4 showers simultaneously for around $400. I have and easy run (electrical) to my fuse panel, which I could run the electrical and then have the installer finish the work.

Imola, I have just replaced a gas-fired tank-type hot water heater with a whole house electric HWOD model. In the end, including the cost of the HWOD unit (about $550) I spent about $2,500, and that was with me pulling the 6-3 w/ground wires that the two 60-amp breakers required. That $2,500 included a changeover from 100 amp overhead service to 200 amp underground service, $800 of that $2,500 was for labor for the ditching and connecting the underground wires to the new meter box and the new electrical panel on the house's porch, the rest was for new service panels for the house and the detatched two-car garage, which had not had electricity for at least the past 40 years, probably more. The wire was almost free, 150' of 4/0 AL wire for only $75 (the cost differential between what it would have cost to provide me with 150' of overhead AL wire and the larger wire needed for the underground service).

Now, having said that, I think it might be easier for you. You are replacing an existing electrical hot water heater, so you already have what, a 30 amp/240V circuit going to the location? Chances are you might be able to get a 2 chamber HWOD unit that might require two 30 amp/240V circuits. In that case, you could get by with the addition of just one more 30 amp circuit to you existing service panel, as long as your calculations of your usage patterns reveals that you won't be taxing your current service beyond it's limits.

OK, you say you want to use a heater that takes two 40 amp circuits, but you also say you have easy access for running the wires, if so I suspect you could easily run yourself two 8 gauge wires, which I understand will carry 40 amp loads......the hardest part of replacing my old tank-type heater was changing over from natural gas to electrical, you may already have the infrastructure to power one of the mid-size units, but it will depend on the nature of the use you anticipate. For me it was easy, I spend only about 60 days per year at the vacation house, and when I shower I can arrange for everything else in the house to be powered down if need be (however, some of my motivation for switching from 100 amp service to 200 amp service was to avoid just that sort of necessity).

I mention this to illustrate that the plumbing part of installing the HWOD unit was the least of the problems, I just hung the HWOD unit near where the old gas-fired water heater stood and hooked the HWOD unit to the current cold water supply and hot water out pipes with 3/4" X 3/4" flexible copper supply lines and it was a done deal--no leaks, no worries, no need for a plumber at all.......

Having made the switch from natural gas to electrical did, however, allow me to disconnect from the natural gas company's distribution network. I may spend another $20 or so per month on electricity, but I did manage to ditch a minimum $40/month natural gas bill. And, to make it even better, the local poco will now offer me a reduction of about 40% on my electrical service b/c I am now "...all electric".

It will take a long time before I could ever recoup the $2,500, that's true, if I could ever do so at all, but your case might not represent as significant a retrofit as mine did, at least get some people to come to your house and give you some estimates or advice. This might be a DIY project, if mine was, this most assuredly is!!

Dugly :cool:

imola ghost 09-07-2008 05:24 PM

Thanks for the information.

I just looked at my breaker panel and my current 55gallon electric water heater is using 2 - 30 amp breakers.

Now another thing is that my idea was that using/getting a tankless water heater was going to save us money some money. I know one problem that we have is that in the master bathroom it takes about 1 minute of running water for the shower to get warm/hot. That is definitely wasting a lot of water even though it's just my wife and I using it. I mean we are probably wasting about 7 gallons of water every shower just to get it warm enough to shower. I think the reason is that our master bathroom is so far away from out water heater.

I don't know if a tankless is out best option. I like the idea of having one because they seem to save water, and I would gain some space in my garage.

Wildie 09-07-2008 05:28 PM

Quote:

Originally Posted by imola ghost (Post 155264)
I'm considering replacing my 55 gallon electric water heater. Though I won't do this myself but wanted to know what kind of savings I would see vs. going the conventional water heater style?

I've heard that using a "electric" tankless water heater was not as efficient as a conventional water heater but rather a gas tankless was the way to save. I don't have a choice as my area doesn't have gas. Now this was something I heard so I cannot confirm whether its true.

If someone has some information about this subject I'd love to hear about it.

A retrofit in my area is not a good idea! For six months its necessary to heat our house.
Heat losses from the regular HW tank help with the heat load in the winter.
In summer, of course this heat loss must be removed by the air conditioner. Our cooling season is only about 2 months long, whereas we heat for six months.
The big advantage of tankless would be less water wastage. Our water is metered and we pay a sewer surcharge based on water consumption.
Perhaps on new construction or a major upgrade it could be justified, but not to replace an existing system. There would be no payback!

imola ghost 09-07-2008 05:33 PM

We live in Florida and we pay the same way, with water metered and pay a sewer surcharge based on water consumption also.

YerDugliness 09-07-2008 05:55 PM

Quote:

Originally Posted by imola ghost (Post 155981)
Thanks for the information.

I just looked at my breaker panel and my current 55gallon electric water heater is using 2 - 30 amp breakers.

I know one problem that we have is that in the master bathroom it takes about 1 minute of running water for the shower to get warm/hot. That is definitely wasting a lot of water even though it's just my wife and I using it. I mean we are probably wasting about 7 gallons of water every shower just to get it warm enough to shower.

It is possible to power an electric HWOD unit with two 40 amp 220V circuits, see here:

http://www.titanheater.com/proddetai...prod=Tempra-15

Other than that, the other units I notice in the same amperage range use one, single double pole 240V breaker, most of them using a 50 or 60 amp breaker. Since you have adequate space to string new wiring from the breaker panel, you might (again, remember, it all depends on your load usage calculations) be able to replace those two 30 amp circuits your current 55 gallon heater uses with one 60 amp circuit and new heavier gauge wiring and power something like this:

http://www.titanheater.com/proddetai...prod=SCR2-N100

or even this:

http://www.titanheater.com/proddetai...prod=SCR2-N120


As for the water waste, I did notice that it seemed to take longer for the water to get hot at the shower, but it might be that I just don't recall how long it took with the old gas-fired tanked heater--it was 4 years ago!! What I did was to order a special constant pressure/low flow shower head from the source I used for the HWOD unit. My HWOD unit requires a flow rate of 0.53 gallons per minute to activate, the shower head maintains the flow rate at 1.5 gallons per minute, and before I even pull that faucet on the shower I rotate it to provide pure hot water. I did also insulate the hot water pipes, seems to take only about 20 seconds now at 1.5 gpm, that's a loss of 0.5 gallons before it is up to full temperature. I usually stick a bucket under the tub faucet while I'm waiting for it to heat up and use the water for plants or rinse water at the kitchen sink (water is quite scarce where this vacation home is located, extreme SW KS, so I attempt to make use of almost all "waste water" in a creative manner).

Dugly :cool:

jerryh3 09-07-2008 06:37 PM

Quote:

Originally Posted by Wildie (Post 155983)
A retrofit in my area is not a good idea! For six months its necessary to heat our house.
Heat losses from the regular HW tank help with the heat load in the winter.
In summer, of course this heat loss must be removed by the air conditioner. Our cooling season is only about 2 months long, whereas we heat for six months.
The big advantage of tankless would be less water wastage. Our water is metered and we pay a sewer surcharge based on water consumption.
Perhaps on new construction or a major upgrade it could be justified, but not to replace an existing system. There would be no payback!

How does a tankless allow you to use less water?

junkcollector 09-07-2008 07:36 PM

The smaller units that don't require much power may not be big enough for your application. These things have a tendency to cause a real annoying light flicker. The power company may need to install a larger transformer and secondary conductors as well.

Quote:

I just looked at my breaker panel and my current 55gallon electric water heater is using 2 - 30 amp breakers.
Do the breakers have a tie bar connecting them? I'm thinking you are talking about one double pole breaker. (Single circuit)
Quote:

I know one problem that we have is that in the master bathroom it takes about 1 minute of running water for the shower to get warm/hot. That is definitely wasting a lot of water even though it's just my wife and I using it. I mean we are probably wasting about 7 gallons of water every shower just to get it warm enough to shower. I think the reason is that our master bathroom is so far away from out water heater.
This is going to be a problem no matter what kind of water heater you have. In order to solve it, you may have to install a recirculating pump, or a larger dedicated line running directly to the bathroom.
Quote:

I like the idea of having one because they seem to save water
Please explain this!

Some other threads regarding tankless electrics

http://www.diychatroom.com/f18/wiring-tankless-water-heater-23497/
http://www.diychatroom.com/f18/electricl-installation-electric-tankless-water-heater-23153/

KC Brick Layer 09-07-2008 07:47 PM

Quote:

Originally Posted by imola ghost (Post 155981)
Thanks for the information.

I just looked at my breaker panel and my current 55gallon electric water heater is using 2 - 30 amp breakers.

Now another thing is that my idea was that using/getting a tankless water heater was going to save us money some money. I know one problem that we have is that in the master bathroom it takes about 1 minute of running water for the shower to get warm/hot. That is definitely wasting a lot of water even though it's just my wife and I using it. I mean we are probably wasting about 7 gallons of water every shower just to get it warm enough to shower. I think the reason is that our master bathroom is so far away from out water heater.

I don't know if a tankless is out best option. I like the idea of having one because they seem to save water, and I would gain some space in my garage.

Im not a plumber but i think you would still have to let the water run long enough for the hot water to make it to your shower. Same as a hot water tank anyways. unless your installing it closer to your shower.


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