Electric On-Demand Tankless Water Heaters

cobraboy

Pro-Bono Demolition Hobbyist
Jul 24, 2004
40,964
936
113
We have a traditional 10 gallon 110v electric water heater that is a pain to manage (off/on switch), takes a while to heat and most likely low efficiency. And 10 gallons doesn't go very far for 2 people.

I'd like to install a propane instant-on tankless system as a replacement, but because of the structure of the house it would require some significant alterations for propane storage and exhaust venting. Not sure I want to do that.

I'm looking into the electric systems, but not the showerhead type (it's spooky having electric wires in the shower area :eek:). For one thing it would be a very easy conversion since it could be in the same place as the electric. I would go with a 220v system because the ground water here in the mountains is much cooler than elsewhere; running another wire would be dooable and the most difficult part of the conversion...and it wouldn't be that hard.

We were at Americana recently and they had a number of systems on display
  • Blue Wave from Israel
  • Stiebel from Germany (most expensive)
  • Eemax from the US

They all come with models depending on the capacity and advanced features-mainly adjustable temperature. Our needs are modest and we just want it to heat the water; we can adjust temperature by mixing cold water as always.

The prices range fron RD$10,000 to 18,000 for the models that would work for our needs. We have a excellent electricial/plumber for the install-same guy who did an great job with our inverter installation.

Just wondering about experiences from the DR1 crowd. I'm concerned about the use, quality of product, any problems and any changes in the cost of your elecricity after your conversion.

Thanks!
 

waytogo

Moderator - North Coast Forum
Apr 3, 2009
6,407
580
113
Santiago DR
Just for your information, besides owning private schools in Arizona, I owned a private drug and alcohol recovery center for women in Prescott Arizona. The center was designed for 24 women and we were always full. When I upgraded the plumbing system, I had an exterior Commercial Outdoor Tankless Water Heater, natural gas (LP was available) installed, and it was fantastic. It would handle any load that the women would put on it. The center had 6 shower stalls and a commercial kitchen and it never ran short of hot water, never. This was 6 showers running almost non-stop. The commercial unit at that time was about $1000. at Home Depot and the residential was about 200. less.
 

pedrochemical

Silver
Aug 22, 2008
3,410
465
0
For me the problem was always finding one that was powerful enough.
They need to be powerful enough to heat the water as fast as you want to use it.

That was however un the UK.
If US fridges and washing machines are anything to go by then you might find one that provides the torrential flood of piping hot water that I like to shower under.


To recap';
Look at the power rating.
An 11.5Kw (240v) system was not really fast enough for a decent shower in my opinion.
 

J D Sauser

Silver
Nov 20, 2004
2,940
390
83
www.hispanosuizainvest.com
I can't share much experience on the systems you are looking at.
Yes, electric shower heads are "spooky" and most who had them over years, will report of having felt a "buzz" or "zap" indicating the device's end of life.
However, on most electric water heating systems, electricity and water get very, very close. So, quality is essential, and so would be maintenance and accepting the device's limited life. Most electric shower heads are of poor quality and may thus pose an additional risk over the systems you are looking at.

However, in a country where electric power traditionally is an "on & off" situation, I don't think that an "instant"-water heater would seem a an enjoyable solution. This is why -in a sharp contrast to many other Latin American countries- even electric shower heads have not caught on much in this nation's market.
They would not be recommended to run on the inverter circuit... unless you have 16 batteries or so.

If I were you, I'd revisit the idea of either a small boiler... even individual ones per location as they will give you a "battery effect" and yield some warm water even after the power is gone or gas heaters with a small local gas tank. They use little energy, so one can every once in a while schlepp that tank to a particular location. A BBQ grill sized one may suffice for a bath room for quite a good number of showers.

Now gas heaters have an other problem here, which is the water pressure. Automatic gas heaters will only turn on automatically IF a minimum flow requirement is meat. Manual ones too, will shut down automatically if the flow of water is to little, as a security measure, so gas does not run without being burned. The trick is, to have some acceptable pressure during pump cycles (in case you have a pump-pressure tank arrangement) and also choose SMALL gas heaters for each outlet.


... J-D.
 

J D Sauser

Silver
Nov 20, 2004
2,940
390
83
www.hispanosuizainvest.com
Cobraboy, ever thought about throwing a 100 ft 3/4'' garden hose on the roof, that goes into a tank that feeds your hot water tubing.

That will get a lot hotter than you can imagine, and it's free(after the initial installation and purchase)

And that's true too.
I witnessed such an installation once in Southern Germany. It was on top of the roof of the cabins of a public pool park... just for the showers and to speed up the "season" in May/June. Well, May came in and soon the Olympic pool was considered too hot already! The "pool guy" turned the hot water cycle to that pool off... soon thereafter, the whole system -it was still only May- started to act like a sprinkler system, blowing hot water thru all the safety valves... TOO much hot water! ... just with black 1/2" PVC pipes.

... J-D.
 

J D Sauser

Silver
Nov 20, 2004
2,940
390
83
www.hispanosuizainvest.com
We're very happy with our roof based solar panel water heater. It has halved the monthly electricity bills.

Btw. CB, just in case, you should never think that the "cooler" climate of Jarabacoa would in anyway hinder a good result with a solar water heating solution. I re-installed a very simple system in 1995 in CUENCA-Ecuador. As you may know, Cuenca is at around 2500 meters altitude and can be quite chilly for most of the year. The result, once the panels were connected adequately, was... erm... may we say quite "spectacular"... the 5 cubic meter reserve steel tank exploded at 05:00 in the morning because of a faulty pressure valve!

... J-D.
 

tflea

Bronze
Jun 11, 2006
1,839
164
63
Tried One

We tried the electric instant hot for about 18 months but the calcification kept making it break down, clog up, and are satisfied with the old traditional barrel water heater. Solar up front cost seemed a poor pay-back unless one plans on a longer term plan than we were willing to go for, even while paying a 4.6 peso per kwh premium for 24-7 power.
 

bayaguanaman

New member
Oct 22, 2009
266
12
0
I was always of the belief (and still am) with the electric water heaters that are controlled by thermostat and have insulated wrapping around the storage tank, the cheapest way to run the system was to keep the water heater switched on all the time. Which if you are using a 220V heating element (in my case 2), and not running through the invertor, i accept is difficult, but when the street power comes on, you basically heat the volume of water that you had used before and then the system reaches the temp setting and closes off anyway.

Whilst on maybe someone can help me understand the 220V system here which I cannot fathom out !!!. I was asked by the elec company if I wanted (needed) 220V to the house, I said yes, so they installed 2 wires as the supply. (Both having the neutral or ground sheathing around the positive internal core....all good. Yet when I needed 220V for the gate and the a/c water heater as above, they simply took I would imagine 2 wires as positive (from the dist box and through seperate breakers) and fed to the equipment concerned. Question therefore, if I am feeding say the water heater or a/c unit with 2 hot (+) feeds only, how does the thing work as in the UK you needed both positive & negative connected.

Maybe I am overlooking the obvious, but having looked at this system for many hours, I simply cannot fathom how it works, but it does so that suggests another beer is therefore needed !! Thanks. I look fwd to being in the DR next week and proud to show I know how it works LOL !. Thanks again.
 

cobraboy

Pro-Bono Demolition Hobbyist
Jul 24, 2004
40,964
936
113
I rent this house so I won't invest in solar. There isn't that much calcification on the water fixtures and they have been here for a while. As a Floridian, I KNOW what bad water does. We had to have a softener to take huge quantities of calcium from the water.

Maybe an occasional douching with Lime Away or an equivalent product would help keep it clean. Would not be hard to do

I wish propane was an option. And if tank heater management is a semi-hassle, I'm pretty sure a protable boiler would be a disaster.

Hose on the roof? Meh. I dunno.

I'll do some more investigation. I spoke to some folks today from Santiago who say their tankless electric has lasted several years.

The Stiebel unit, the most expensive, has a 3 year warranty (yes, I undertsand how warranties work in the DR.) This is the link to the unit: Stiebel Eltron | DHC-E Tankless Electric Water Heater

Research continues, thanks for the input. I value all of it.
 

cobraboy

Pro-Bono Demolition Hobbyist
Jul 24, 2004
40,964
936
113
I was always of the belief (and still am) with the electric water heaters that are controlled by thermostat and have insulated wrapping around the storage tank, the cheapest way to run the system was to keep the water heater switched on all the time. Which if you are using a 220V heating element (in my case 2), and not running through the invertor, i accept is difficult, but when the street power comes on, you basically heat the volume of water that you had used before and then the system reaches the temp setting and closes off anyway.

Whilst on maybe someone can help me understand the 220V system here which I cannot fathom out !!!. I was asked by the elec company if I wanted (needed) 220V to the house, I said yes, so they installed 2 wires as the supply. (Both having the neutral or ground sheathing around the positive internal core....all good. Yet when I needed 220V for the gate and the a/c water heater as above, they simply took I would imagine 2 wires as positive (from the dist box and through seperate breakers) and fed to the equipment concerned. Question therefore, if I am feeding say the water heater or a/c unit with 2 hot (+) feeds only, how does the thing work as in the UK you needed both positive & negative connected.

Maybe I am overlooking the obvious, but having looked at this system for many hours, I simply cannot fathom how it works, but it does so that suggests another beer is therefore needed !! Thanks. I look fwd to being in the DR next week and proud to show I know how it works LOL !. Thanks again.
2 110v hot + ground=220v

But the hots have to be from a separate street feed. They may be in your circuit box, but they're separate.

I think...
 

Lambada

Gold
Mar 4, 2004
9,478
410
0
80
www.ginniebedggood.com
Solar up front cost seemed a poor pay-back unless one plans on a longer term plan than we were willing to go for, even while paying a 4.6 peso per kwh premium for 24-7 power.

I think it took two years to recoup our upfront costs via the reduced monthly electricity bill but I'll defer to BushBaby on that one as he was the guy working out the figures and in charge of the project.

I forgot that cobraboy was renting, I thought he was an owner. Certainly not an economically sound idea if one is likely to move on after a year or so.
 

ffritz

New member
Feb 7, 2008
463
30
0
www.gymbar.blogspot.com
We have a hot water tank heater - electric - & leave it running 24/7.

Last summer we turned it off & the saving was only about RD200 on our power bill.

IMHO for the convenience of hot water "on tap" that is a small price to pay.
 

BushBaby

Silver
Jan 1, 2002
3,829
329
0
79
www.casabush.org
but I'll defer to BushBaby on that one as he was the guy working out the figures and in charge of the project.
Can I have that in writing please????:cheeky: ;) You will defer to me on something???? :cheeky: Wow!!

The unit cost us some RD $64,000 for the two panels, relevant pipework (linking directly into our existing hot water tank to my specs) & a 100 gallon tank on the roof. We were paying top end electricity rates (RD $11. something) per KWh for being over the 700 KWh per month usage. By installing the solar panels & tank for our hot water we came below the 700 KWh per month usage & so paid only (on average) 5.2 pesos per KWh. This meant a saving of RD $3,600 per month initially (slightly less now with additional electrical equipment installed due to SWMBO's opulence!) so it paid for itself in 19 months. Hot water is now F R E E so Up Yours Edenorte!! :cheeky::cheeky:

I tried searching for the old post so as to give credence to this post but unfortunately the 'link words/tags' I have used so far have yielded me Zilch. If anyone is interested in the installers details, PM me & I'll try a workaround to get his phone number/address. He was in Santiago but worked the whole north coast! ~ Grahame.
 

wuarhat

I am a out of touch hippie.
Nov 13, 2006
1,378
89
48
I had two of the Emax electrical units, if I remember correctly, in my house in Puerto Plata. They provided scalding hot water under normal use. (50 lb..pressure)

Both gave me problems after a couple of years due to mineral buildup inside that affected the on/off relay.

If I were to buy another, I'd make sure they could be disassembled for maintenance and/or repair.

For now, I have a 20 gal 220V heater with a 1 hr. maximum timer switch.

When I go to bed at night, I set the timer on 20 minutes, and when I get up in the morning, the water is still hot as hell.

My electric bill runs about 1200 pesos a month. (Yep, 1,200, not 12000)

I?ve been looking at tankless water heaters a lot lately and have seen recommendations for installing them with a shutoff and union on the hot water and cold water pipe. Annually you can connect a device consisting of a pump, a reservoir, and tubing that connects to the unions, and circulate a mixture of vinegar and water through it for about a day. (remove the power) They say that resolves the buildup issue.

I was always of the belief (and still am) with the electric water heaters that are controlled by thermostat and have insulated wrapping around the storage tank, the cheapest way to run the system was to keep the water heater switched on all the time. Which if you are using a 220V heating element (in my case 2), and not running through the invertor, i accept is difficult, but when the street power comes on, you basically heat the volume of water that you had used before and then the system reaches the temp setting and closes off anyway.

Whilst on maybe someone can help me understand the 220V system here which I cannot fathom out !!!. I was asked by the elec company if I wanted (needed) 220V to the house, I said yes, so they installed 2 wires as the supply. (Both having the neutral or ground sheathing around the positive internal core....all good. Yet when I needed 220V for the gate and the a/c water heater as above, they simply took I would imagine 2 wires as positive (from the dist box and through seperate breakers) and fed to the equipment concerned. Question therefore, if I am feeding say the water heater or a/c unit with 2 hot (+) feeds only, how does the thing work as in the UK you needed both positive & negative connected.

Maybe I am overlooking the obvious, but having looked at this system for many hours, I simply cannot fathom how it works, but it does so that suggests another beer is therefore needed !! Thanks. I look fwd to being in the DR next week and proud to show I know how it works LOL !. Thanks again.

You better grab that beer, because I need trigonometry and algebra to explain it. The 240 volt power has two 120 volt wires, each 180 degrees out of phase with the other. Since the voltage on each is alternating between 120 and minus 120 in a sinusoidal fashion 60 times a second, you can use the trigonometric identity that the sine of an angle is equal to minus the sine of the same angle minus 180 degrees. (sine (a) = - sine (a-180degrees)) So one of your wires is 120sine(a) and the other is -120sine(a), and 120-(-120)=240. You don?t need neutral for the equipment to function, however it should be grounded for safety sake. Unfortunately safety is not too highly regarded in the DR.
 

J D Sauser

Silver
Nov 20, 2004
2,940
390
83
www.hispanosuizainvest.com
I was always of the belief (and still am) with the electric water heaters that are controlled by thermostat and have insulated wrapping around the storage tank, the cheapest way to run the system was to keep the water heater switched on all the time.

I got a very small boiler (WH) in the house I rent... the typical cheap low efficiency local contractor's special... s m a l l , ill insulated.

We have 23/7 power. The boiler is obviously NOT on the inverter circuit.

Since I had guests for over a year, we were nearing the 700 KWH whack rate a few times and once went blew thru it. I thought once was once too many so I searched for ways to lower our consumption without "giving" up any comfort. I don't like to compromise.

ALL our lighting is neon or CFL based. I have 5 perimeter lights on the outside I left running 24/7 to make sure they would be ON by dusk. Obviously that was one weak spot but 5 times 8 Watts? Anyways, I replaced their switches with electronic timer switches I got online from Home Depot.

That made a change for sure, but only worth about 15 KWH per month.

So, we kept on searching. I decided that we'd try an put the little boiler on a timer too. It kicks in early and mid mornings, before noon and, around 16:00 and in the evening each for 30 min (which we established was the time it needs to heat up from scratch).
And surprise-surprise, without loosing any comfort, this saved us well over 100 KWH per month! That little sucker had it going for it... silently.
I am sure, results would be less dramatic even with a larger size but QUALITY water heater with a high efficiency rating, like the ones available in the US or EU.

Back to CB's issue and "Solar".

CB, assuming you are still living in the same house I met you last year, you would have enough garden to rig up a "portable" solar water heating system you could later adapt in a house of your own.


... J-D.
 

cobraboy

Pro-Bono Demolition Hobbyist
Jul 24, 2004
40,964
936
113
CB, assuming you are still living in the same house I met you last year, you would have enough garden to rig up a "portable" solar water heating system you could later adapt in a house of your own.


... J-D.
We moved down the road to more modest digs...:)
 

SantiagoDR

The "REAL" SantiagoDR
Jan 12, 2006
5,808
948
113
....
Whilst on maybe someone can help me understand the 220V system here which I cannot fathom out !!!. I was asked by the elec company if I wanted (needed) 220V to the house, I said yes, so they installed 2 wires as the supply. (Both having the neutral or ground sheathing around the positive internal core....all good. Yet when I needed 220V for the gate and the a/c water heater as above, they simply took I would imagine 2 wires as positive (from the dist box and through seperate breakers) and fed to the equipment concerned. Question therefore, if I am feeding say the water heater or a/c unit with 2 hot (+) feeds only, how does the thing work as in the UK you needed both positive & negative connected.
...........
The answer is quite simple.

The transformer on the pole puts out 220vac (+/-) and is center tapped.

Connecting from side-to-side from the transformer gives you the 220vac (+/-)
Connecting from either side to the center tap gives you 110vac (+/-)/

The center tap is ground, the ground is not used to obtain the 220vac.

(vac: Volts A/C)

t9d26v.gif

SantiagoDR
 

bayaguanaman

New member
Oct 22, 2009
266
12
0
Gentlemen above, the explanation is just what I needed to be able to put this to the back of my mind, thanks !. It just seems to go against what I thought was needed a supply in, through the motor winding or light and a return, never thinking that the alternating current was infact doing this 60 times per second.

Beer please !
 
  • Like
Reactions: wuarhat